/usr/lib/python3/dist-packages/paramiko/transport.py is in python3-paramiko 2.0.0-1ubuntu1.2.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 945 946 947 948 949 950 951 952 953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152 1153 1154 1155 1156 1157 1158 1159 1160 1161 1162 1163 1164 1165 1166 1167 1168 1169 1170 1171 1172 1173 1174 1175 1176 1177 1178 1179 1180 1181 1182 1183 1184 1185 1186 1187 1188 1189 1190 1191 1192 1193 1194 1195 1196 1197 1198 1199 1200 1201 1202 1203 1204 1205 1206 1207 1208 1209 1210 1211 1212 1213 1214 1215 1216 1217 1218 1219 1220 1221 1222 1223 1224 1225 1226 1227 1228 1229 1230 1231 1232 1233 1234 1235 1236 1237 1238 1239 1240 1241 1242 1243 1244 1245 1246 1247 1248 1249 1250 1251 1252 1253 1254 1255 1256 1257 1258 1259 1260 1261 1262 1263 1264 1265 1266 1267 1268 1269 1270 1271 1272 1273 1274 1275 1276 1277 1278 1279 1280 1281 1282 1283 1284 1285 1286 1287 1288 1289 1290 1291 1292 1293 1294 1295 1296 1297 1298 1299 1300 1301 1302 1303 1304 1305 1306 1307 1308 1309 1310 1311 1312 1313 1314 1315 1316 1317 1318 1319 1320 1321 1322 1323 1324 1325 1326 1327 1328 1329 1330 1331 1332 1333 1334 1335 1336 1337 1338 1339 1340 1341 1342 1343 1344 1345 1346 1347 1348 1349 1350 1351 1352 1353 1354 1355 1356 1357 1358 1359 1360 1361 1362 1363 1364 1365 1366 1367 1368 1369 1370 1371 1372 1373 1374 1375 1376 1377 1378 1379 1380 1381 1382 1383 1384 1385 1386 1387 1388 1389 1390 1391 1392 1393 1394 1395 1396 1397 1398 1399 1400 1401 1402 1403 1404 1405 1406 1407 1408 1409 1410 1411 1412 1413 1414 1415 1416 1417 1418 1419 1420 1421 1422 1423 1424 1425 1426 1427 1428 1429 1430 1431 1432 1433 1434 1435 1436 1437 1438 1439 1440 1441 1442 1443 1444 1445 1446 1447 1448 1449 1450 1451 1452 1453 1454 1455 1456 1457 1458 1459 1460 1461 1462 1463 1464 1465 1466 1467 1468 1469 1470 1471 1472 1473 1474 1475 1476 1477 1478 1479 1480 1481 1482 1483 1484 1485 1486 1487 1488 1489 1490 1491 1492 1493 1494 1495 1496 1497 1498 1499 1500 1501 1502 1503 1504 1505 1506 1507 1508 1509 1510 1511 1512 1513 1514 1515 1516 1517 1518 1519 1520 1521 1522 1523 1524 1525 1526 1527 1528 1529 1530 1531 1532 1533 1534 1535 1536 1537 1538 1539 1540 1541 1542 1543 1544 1545 1546 1547 1548 1549 1550 1551 1552 1553 1554 1555 1556 1557 1558 1559 1560 1561 1562 1563 1564 1565 1566 1567 1568 1569 1570 1571 1572 1573 1574 1575 1576 1577 1578 1579 1580 1581 1582 1583 1584 1585 1586 1587 1588 1589 1590 1591 1592 1593 1594 1595 1596 1597 1598 1599 1600 1601 1602 1603 1604 1605 1606 1607 1608 1609 1610 1611 1612 1613 1614 1615 1616 1617 1618 1619 1620 1621 1622 1623 1624 1625 1626 1627 1628 1629 1630 1631 1632 1633 1634 1635 1636 1637 1638 1639 1640 1641 1642 1643 1644 1645 1646 1647 1648 1649 1650 1651 1652 1653 1654 1655 1656 1657 1658 1659 1660 1661 1662 1663 1664 1665 1666 1667 1668 1669 1670 1671 1672 1673 1674 1675 1676 1677 1678 1679 1680 1681 1682 1683 1684 1685 1686 1687 1688 1689 1690 1691 1692 1693 1694 1695 1696 1697 1698 1699 1700 1701 1702 1703 1704 1705 1706 1707 1708 1709 1710 1711 1712 1713 1714 1715 1716 1717 1718 1719 1720 1721 1722 1723 1724 1725 1726 1727 1728 1729 1730 1731 1732 1733 1734 1735 1736 1737 1738 1739 1740 1741 1742 1743 1744 1745 1746 1747 1748 1749 1750 1751 1752 1753 1754 1755 1756 1757 1758 1759 1760 1761 1762 1763 1764 1765 1766 1767 1768 1769 1770 1771 1772 1773 1774 1775 1776 1777 1778 1779 1780 1781 1782 1783 1784 1785 1786 1787 1788 1789 1790 1791 1792 1793 1794 1795 1796 1797 1798 1799 1800 1801 1802 1803 1804 1805 1806 1807 1808 1809 1810 1811 1812 1813 1814 1815 1816 1817 1818 1819 1820 1821 1822 1823 1824 1825 1826 1827 1828 1829 1830 1831 1832 1833 1834 1835 1836 1837 1838 1839 1840 1841 1842 1843 1844 1845 1846 1847 1848 1849 1850 1851 1852 1853 1854 1855 1856 1857 1858 1859 1860 1861 1862 1863 1864 1865 1866 1867 1868 1869 1870 1871 1872 1873 1874 1875 1876 1877 1878 1879 1880 1881 1882 1883 1884 1885 1886 1887 1888 1889 1890 1891 1892 1893 1894 1895 1896 1897 1898 1899 1900 1901 1902 1903 1904 1905 1906 1907 1908 1909 1910 1911 1912 1913 1914 1915 1916 1917 1918 1919 1920 1921 1922 1923 1924 1925 1926 1927 1928 1929 1930 1931 1932 1933 1934 1935 1936 1937 1938 1939 1940 1941 1942 1943 1944 1945 1946 1947 1948 1949 1950 1951 1952 1953 1954 1955 1956 1957 1958 1959 1960 1961 1962 1963 1964 1965 1966 1967 1968 1969 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025 2026 2027 2028 2029 2030 2031 2032 2033 2034 2035 2036 2037 2038 2039 2040 2041 2042 2043 2044 2045 2046 2047 2048 2049 2050 2051 2052 2053 2054 2055 2056 2057 2058 2059 2060 2061 2062 2063 2064 2065 2066 2067 2068 2069 2070 2071 2072 2073 2074 2075 2076 2077 2078 2079 2080 2081 2082 2083 2084 2085 2086 2087 2088 2089 2090 2091 2092 2093 2094 2095 2096 2097 2098 2099 2100 2101 2102 2103 2104 2105 2106 2107 2108 2109 2110 2111 2112 2113 2114 2115 2116 2117 2118 2119 2120 2121 2122 2123 2124 2125 2126 2127 2128 2129 2130 2131 2132 2133 2134 2135 2136 2137 2138 2139 2140 2141 2142 2143 2144 2145 2146 2147 2148 2149 2150 2151 2152 2153 2154 2155 2156 2157 2158 2159 2160 2161 2162 2163 2164 2165 2166 2167 2168 2169 2170 2171 2172 2173 2174 2175 2176 2177 2178 2179 2180 2181 2182 2183 2184 2185 2186 2187 2188 2189 2190 2191 2192 2193 2194 2195 2196 2197 2198 2199 2200 2201 2202 2203 2204 2205 2206 2207 2208 2209 2210 2211 2212 2213 2214 2215 2216 2217 2218 2219 2220 2221 2222 2223 2224 2225 2226 2227 2228 2229 2230 2231 2232 2233 2234 2235 2236 2237 2238 2239 2240 2241 2242 2243 2244 2245 2246 2247 2248 2249 2250 2251 2252 2253 2254 2255 2256 2257 2258 2259 2260 2261 2262 2263 2264 2265 2266 2267 2268 2269 2270 2271 2272 2273 2274 2275 2276 2277 2278 2279 2280 2281 2282 2283 2284 2285 2286 2287 2288 2289 2290 2291 2292 2293 2294 2295 2296 2297 2298 2299 2300 2301 2302 2303 2304 2305 2306 2307 2308 2309 2310 2311 2312 2313 2314 2315 2316 2317 2318 2319 2320 2321 2322 2323 2324 2325 2326 2327 2328 2329 2330 2331 2332 2333 2334 2335 2336 2337 2338 2339 2340 2341 2342 2343 2344 2345 2346 2347 2348 2349 2350 2351 2352 2353 2354 2355 2356 2357 2358 2359 2360 2361 2362 2363 2364 2365 2366 2367 2368 2369 2370 2371 2372 2373 2374 2375 2376 2377 2378 2379 2380 2381 2382 2383 2384 2385 2386 2387 2388 2389 2390 2391 2392 2393 2394 2395 2396 2397 2398 2399 2400 2401 2402 2403 2404 2405 2406 2407 2408 2409 2410 2411 2412 2413 2414 2415 2416 2417 2418 2419 2420 2421 2422 2423 2424 2425 2426 2427 2428 2429 2430 2431 2432 2433 2434 2435 2436 2437 2438 2439 2440 2441 2442 2443 2444 2445 2446 2447 2448 2449 2450 2451 2452 2453 2454 2455 2456 2457 2458 2459 2460 2461 2462 2463 2464 2465 2466 2467 2468 2469 2470 2471 2472 2473 2474 2475 2476 2477 2478 2479 2480 2481 2482 2483 2484 2485 2486 2487 2488 2489 2490 2491 2492 2493 2494 2495 2496 2497 2498 2499 2500 2501 2502 2503 2504 2505 2506 2507 2508 2509 2510 2511 2512 2513 2514 2515 2516 2517 2518 2519 2520 2521 2522 2523 2524 2525 2526 2527 2528 2529 2530 2531 2532 2533 2534 2535 2536 2537 2538 2539 2540 2541 2542 2543 | # Copyright (C) 2003-2007 Robey Pointer <robeypointer@gmail.com>
#
# This file is part of paramiko.
#
# Paramiko is free software; you can redistribute it and/or modify it under the
# terms of the GNU Lesser General Public License as published by the Free
# Software Foundation; either version 2.1 of the License, or (at your option)
# any later version.
#
# Paramiko is distributed in the hope that it will be useful, but WITHOUT ANY
# WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
# A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
# details.
#
# You should have received a copy of the GNU Lesser General Public License
# along with Paramiko; if not, write to the Free Software Foundation, Inc.,
# 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
"""
Core protocol implementation
"""
from __future__ import print_function
import os
import socket
import sys
import threading
import time
import weakref
from hashlib import md5, sha1, sha256, sha512
from cryptography.hazmat.backends import default_backend
from cryptography.hazmat.primitives.ciphers import algorithms, Cipher, modes
import paramiko
from paramiko import util
from paramiko.auth_handler import AuthHandler
from paramiko.ssh_gss import GSSAuth
from paramiko.channel import Channel
from paramiko.common import xffffffff, cMSG_CHANNEL_OPEN, cMSG_IGNORE, \
cMSG_GLOBAL_REQUEST, DEBUG, MSG_KEXINIT, MSG_IGNORE, MSG_DISCONNECT, \
MSG_DEBUG, ERROR, WARNING, cMSG_UNIMPLEMENTED, INFO, cMSG_KEXINIT, \
cMSG_NEWKEYS, MSG_NEWKEYS, cMSG_REQUEST_SUCCESS, cMSG_REQUEST_FAILURE, \
CONNECTION_FAILED_CODE, OPEN_FAILED_ADMINISTRATIVELY_PROHIBITED, \
OPEN_SUCCEEDED, cMSG_CHANNEL_OPEN_FAILURE, cMSG_CHANNEL_OPEN_SUCCESS, \
MSG_GLOBAL_REQUEST, MSG_REQUEST_SUCCESS, MSG_REQUEST_FAILURE, \
MSG_CHANNEL_OPEN_SUCCESS, MSG_CHANNEL_OPEN_FAILURE, MSG_CHANNEL_OPEN, \
MSG_CHANNEL_SUCCESS, MSG_CHANNEL_FAILURE, MSG_CHANNEL_DATA, \
MSG_CHANNEL_EXTENDED_DATA, MSG_CHANNEL_WINDOW_ADJUST, MSG_CHANNEL_REQUEST, \
MSG_CHANNEL_EOF, MSG_CHANNEL_CLOSE, MIN_WINDOW_SIZE, MIN_PACKET_SIZE, \
MAX_WINDOW_SIZE, DEFAULT_WINDOW_SIZE, DEFAULT_MAX_PACKET_SIZE, \
HIGHEST_USERAUTH_MESSAGE_ID, MSG_UNIMPLEMENTED, MSG_NAMES
from paramiko.compress import ZlibCompressor, ZlibDecompressor
from paramiko.dsskey import DSSKey
from paramiko.kex_gex import KexGex, KexGexSHA256
from paramiko.kex_group1 import KexGroup1
from paramiko.kex_group14 import KexGroup14
from paramiko.kex_gss import KexGSSGex, KexGSSGroup1, KexGSSGroup14, NullHostKey
from paramiko.message import Message
from paramiko.packet import Packetizer, NeedRekeyException
from paramiko.primes import ModulusPack
from paramiko.py3compat import string_types, long, byte_ord, b, input
from paramiko.rsakey import RSAKey
from paramiko.ecdsakey import ECDSAKey
from paramiko.server import ServerInterface
from paramiko.sftp_client import SFTPClient
from paramiko.ssh_exception import (SSHException, BadAuthenticationType,
ChannelException, ProxyCommandFailure)
from paramiko.util import retry_on_signal, ClosingContextManager, clamp_value
# for thread cleanup
_active_threads = []
def _join_lingering_threads():
for thr in _active_threads:
thr.stop_thread()
import atexit
atexit.register(_join_lingering_threads)
class Transport (threading.Thread, ClosingContextManager):
"""
An SSH Transport attaches to a stream (usually a socket), negotiates an
encrypted session, authenticates, and then creates stream tunnels, called
`channels <.Channel>`, across the session. Multiple channels can be
multiplexed across a single session (and often are, in the case of port
forwardings).
Instances of this class may be used as context managers.
"""
_ENCRYPT = object()
_DECRYPT = object()
_PROTO_ID = '2.0'
_CLIENT_ID = 'paramiko_%s' % paramiko.__version__
# These tuples of algorithm identifiers are in preference order; do not
# reorder without reason!
_preferred_ciphers = (
'aes128-ctr',
'aes192-ctr',
'aes256-ctr',
'aes128-cbc',
'aes192-cbc',
'aes256-cbc',
'blowfish-cbc',
'3des-cbc',
'arcfour128',
'arcfour256',
)
_preferred_macs = (
'hmac-sha2-256',
'hmac-sha2-512',
'hmac-sha1',
'hmac-md5',
'hmac-sha1-96',
'hmac-md5-96',
)
_preferred_keys = (
'ssh-rsa',
'ssh-dss',
) + tuple(ECDSAKey.supported_key_format_identifiers())
_preferred_kex = (
'diffie-hellman-group-exchange-sha256',
'diffie-hellman-group-exchange-sha1',
'diffie-hellman-group14-sha1',
'diffie-hellman-group1-sha1',
)
_preferred_compression = ('none',)
_cipher_info = {
'aes128-ctr': {
'class': algorithms.AES,
'mode': modes.CTR,
'block-size': 16,
'key-size': 16
},
'aes192-ctr': {
'class': algorithms.AES,
'mode': modes.CTR,
'block-size': 16,
'key-size': 24
},
'aes256-ctr': {
'class': algorithms.AES,
'mode': modes.CTR,
'block-size': 16,
'key-size': 32
},
'blowfish-cbc': {
'class': algorithms.Blowfish,
'mode': modes.CBC,
'block-size': 8,
'key-size': 16
},
'aes128-cbc': {
'class': algorithms.AES,
'mode': modes.CBC,
'block-size': 16,
'key-size': 16
},
'aes192-cbc': {
'class': algorithms.AES,
'mode': modes.CBC,
'block-size': 16,
'key-size': 24
},
'aes256-cbc': {
'class': algorithms.AES,
'mode': modes.CBC,
'block-size': 16,
'key-size': 32
},
'3des-cbc': {
'class': algorithms.TripleDES,
'mode': modes.CBC,
'block-size': 8,
'key-size': 24
},
'arcfour128': {
'class': algorithms.ARC4,
'mode': None,
'block-size': 8,
'key-size': 16
},
'arcfour256': {
'class': algorithms.ARC4,
'mode': None,
'block-size': 8,
'key-size': 32
},
}
_mac_info = {
'hmac-sha1': {'class': sha1, 'size': 20},
'hmac-sha1-96': {'class': sha1, 'size': 12},
'hmac-sha2-256': {'class': sha256, 'size': 32},
'hmac-sha2-512': {'class': sha512, 'size': 64},
'hmac-md5': {'class': md5, 'size': 16},
'hmac-md5-96': {'class': md5, 'size': 12},
}
_key_info = {
'ssh-rsa': RSAKey,
'ssh-dss': DSSKey,
'ecdsa-sha2-nistp256': ECDSAKey,
}
_kex_info = {
'diffie-hellman-group1-sha1': KexGroup1,
'diffie-hellman-group14-sha1': KexGroup14,
'diffie-hellman-group-exchange-sha1': KexGex,
'diffie-hellman-group-exchange-sha256': KexGexSHA256,
'gss-group1-sha1-toWM5Slw5Ew8Mqkay+al2g==': KexGSSGroup1,
'gss-group14-sha1-toWM5Slw5Ew8Mqkay+al2g==': KexGSSGroup14,
'gss-gex-sha1-toWM5Slw5Ew8Mqkay+al2g==': KexGSSGex
}
_compression_info = {
# zlib@openssh.com is just zlib, but only turned on after a successful
# authentication. openssh servers may only offer this type because
# they've had troubles with security holes in zlib in the past.
'zlib@openssh.com': (ZlibCompressor, ZlibDecompressor),
'zlib': (ZlibCompressor, ZlibDecompressor),
'none': (None, None),
}
_modulus_pack = None
def __init__(self,
sock,
default_window_size=DEFAULT_WINDOW_SIZE,
default_max_packet_size=DEFAULT_MAX_PACKET_SIZE,
gss_kex=False,
gss_deleg_creds=True):
"""
Create a new SSH session over an existing socket, or socket-like
object. This only creates the `.Transport` object; it doesn't begin the
SSH session yet. Use `connect` or `start_client` to begin a client
session, or `start_server` to begin a server session.
If the object is not actually a socket, it must have the following
methods:
- ``send(str)``: Writes from 1 to ``len(str)`` bytes, and returns an
int representing the number of bytes written. Returns
0 or raises ``EOFError`` if the stream has been closed.
- ``recv(int)``: Reads from 1 to ``int`` bytes and returns them as a
string. Returns 0 or raises ``EOFError`` if the stream has been
closed.
- ``close()``: Closes the socket.
- ``settimeout(n)``: Sets a (float) timeout on I/O operations.
For ease of use, you may also pass in an address (as a tuple) or a host
string as the ``sock`` argument. (A host string is a hostname with an
optional port (separated by ``":"``) which will be converted into a
tuple of ``(hostname, port)``.) A socket will be connected to this
address and used for communication. Exceptions from the ``socket``
call may be thrown in this case.
.. note::
Modifying the the window and packet sizes might have adverse
effects on your channels created from this transport. The default
values are the same as in the OpenSSH code base and have been
battle tested.
:param socket sock:
a socket or socket-like object to create the session over.
:param int default_window_size:
sets the default window size on the transport. (defaults to
2097152)
:param int default_max_packet_size:
sets the default max packet size on the transport. (defaults to
32768)
.. versionchanged:: 1.15
Added the ``default_window_size`` and ``default_max_packet_size``
arguments.
"""
self.active = False
if isinstance(sock, string_types):
# convert "host:port" into (host, port)
hl = sock.split(':', 1)
if len(hl) == 1:
sock = (hl[0], 22)
else:
sock = (hl[0], int(hl[1]))
if type(sock) is tuple:
# connect to the given (host, port)
hostname, port = sock
reason = 'No suitable address family'
for (family, socktype, proto, canonname, sockaddr) in socket.getaddrinfo(hostname, port, socket.AF_UNSPEC, socket.SOCK_STREAM):
if socktype == socket.SOCK_STREAM:
af = family
addr = sockaddr
sock = socket.socket(af, socket.SOCK_STREAM)
try:
retry_on_signal(lambda: sock.connect((hostname, port)))
except socket.error as e:
reason = str(e)
else:
break
else:
raise SSHException(
'Unable to connect to %s: %s' % (hostname, reason))
# okay, normal socket-ish flow here...
threading.Thread.__init__(self)
self.setDaemon(True)
self.sock = sock
# Python < 2.3 doesn't have the settimeout method - RogerB
try:
# we set the timeout so we can check self.active periodically to
# see if we should bail. socket.timeout exception is never
# propagated.
self.sock.settimeout(0.1)
except AttributeError:
pass
# negotiated crypto parameters
self.packetizer = Packetizer(sock)
self.local_version = 'SSH-' + self._PROTO_ID + '-' + self._CLIENT_ID
self.remote_version = ''
self.local_cipher = self.remote_cipher = ''
self.local_kex_init = self.remote_kex_init = None
self.local_mac = self.remote_mac = None
self.local_compression = self.remote_compression = None
self.session_id = None
self.host_key_type = None
self.host_key = None
# GSS-API / SSPI Key Exchange
self.use_gss_kex = gss_kex
# This will be set to True if GSS-API Key Exchange was performed
self.gss_kex_used = False
self.kexgss_ctxt = None
self.gss_host = None
if self.use_gss_kex:
self.kexgss_ctxt = GSSAuth("gssapi-keyex", gss_deleg_creds)
self._preferred_kex = ('gss-gex-sha1-toWM5Slw5Ew8Mqkay+al2g==',
'gss-group14-sha1-toWM5Slw5Ew8Mqkay+al2g==',
'gss-group1-sha1-toWM5Slw5Ew8Mqkay+al2g==',
'diffie-hellman-group-exchange-sha1',
'diffie-hellman-group14-sha1',
'diffie-hellman-group1-sha1')
# state used during negotiation
self.kex_engine = None
self.H = None
self.K = None
self.initial_kex_done = False
self.in_kex = False
self.authenticated = False
self._expected_packet = tuple()
self.lock = threading.Lock() # synchronization (always higher level than write_lock)
# tracking open channels
self._channels = ChannelMap()
self.channel_events = {} # (id -> Event)
self.channels_seen = {} # (id -> True)
self._channel_counter = 0
self.default_max_packet_size = default_max_packet_size
self.default_window_size = default_window_size
self._forward_agent_handler = None
self._x11_handler = None
self._tcp_handler = None
self.saved_exception = None
self.clear_to_send = threading.Event()
self.clear_to_send_lock = threading.Lock()
self.clear_to_send_timeout = 30.0
self.log_name = 'paramiko.transport'
self.logger = util.get_logger(self.log_name)
self.packetizer.set_log(self.logger)
self.auth_handler = None
self.global_response = None # response Message from an arbitrary global request
self.completion_event = None # user-defined event callbacks
self.banner_timeout = 15 # how long (seconds) to wait for the SSH banner
self.handshake_timeout = 15 # how long (seconds) to wait for the handshake to finish after SSH banner sent.
# server mode:
self.server_mode = False
self.server_object = None
self.server_key_dict = {}
self.server_accepts = []
self.server_accept_cv = threading.Condition(self.lock)
self.subsystem_table = {}
def __repr__(self):
"""
Returns a string representation of this object, for debugging.
"""
out = '<paramiko.Transport at %s' % hex(long(id(self)) & xffffffff)
if not self.active:
out += ' (unconnected)'
else:
if self.local_cipher != '':
out += ' (cipher %s, %d bits)' % (self.local_cipher,
self._cipher_info[self.local_cipher]['key-size'] * 8)
if self.is_authenticated():
out += ' (active; %d open channel(s))' % len(self._channels)
elif self.initial_kex_done:
out += ' (connected; awaiting auth)'
else:
out += ' (connecting)'
out += '>'
return out
def atfork(self):
"""
Terminate this Transport without closing the session. On posix
systems, if a Transport is open during process forking, both parent
and child will share the underlying socket, but only one process can
use the connection (without corrupting the session). Use this method
to clean up a Transport object without disrupting the other process.
.. versionadded:: 1.5.3
"""
self.sock.close()
self.close()
def get_security_options(self):
"""
Return a `.SecurityOptions` object which can be used to tweak the
encryption algorithms this transport will permit (for encryption,
digest/hash operations, public keys, and key exchanges) and the order
of preference for them.
"""
return SecurityOptions(self)
def set_gss_host(self, gss_host):
"""
Setter for C{gss_host} if GSS-API Key Exchange is performed.
:param str gss_host: The targets name in the kerberos database
Default: The name of the host to connect to
:rtype: Void
"""
# We need the FQDN to get this working with SSPI
self.gss_host = socket.getfqdn(gss_host)
def start_client(self, event=None):
"""
Negotiate a new SSH2 session as a client. This is the first step after
creating a new `.Transport`. A separate thread is created for protocol
negotiation.
If an event is passed in, this method returns immediately. When
negotiation is done (successful or not), the given ``Event`` will
be triggered. On failure, `is_active` will return ``False``.
(Since 1.4) If ``event`` is ``None``, this method will not return until
negotation is done. On success, the method returns normally.
Otherwise an SSHException is raised.
After a successful negotiation, you will usually want to authenticate,
calling `auth_password <Transport.auth_password>` or
`auth_publickey <Transport.auth_publickey>`.
.. note:: `connect` is a simpler method for connecting as a client.
.. note::
After calling this method (or `start_server` or `connect`), you
should no longer directly read from or write to the original socket
object.
:param .threading.Event event:
an event to trigger when negotiation is complete (optional)
:raises SSHException: if negotiation fails (and no ``event`` was passed
in)
"""
self.active = True
if event is not None:
# async, return immediately and let the app poll for completion
self.completion_event = event
self.start()
return
# synchronous, wait for a result
self.completion_event = event = threading.Event()
self.start()
while True:
event.wait(0.1)
if not self.active:
e = self.get_exception()
if e is not None:
raise e
raise SSHException('Negotiation failed.')
if event.is_set():
break
def start_server(self, event=None, server=None):
"""
Negotiate a new SSH2 session as a server. This is the first step after
creating a new `.Transport` and setting up your server host key(s). A
separate thread is created for protocol negotiation.
If an event is passed in, this method returns immediately. When
negotiation is done (successful or not), the given ``Event`` will
be triggered. On failure, `is_active` will return ``False``.
(Since 1.4) If ``event`` is ``None``, this method will not return until
negotation is done. On success, the method returns normally.
Otherwise an SSHException is raised.
After a successful negotiation, the client will need to authenticate.
Override the methods `get_allowed_auths
<.ServerInterface.get_allowed_auths>`, `check_auth_none
<.ServerInterface.check_auth_none>`, `check_auth_password
<.ServerInterface.check_auth_password>`, and `check_auth_publickey
<.ServerInterface.check_auth_publickey>` in the given ``server`` object
to control the authentication process.
After a successful authentication, the client should request to open a
channel. Override `check_channel_request
<.ServerInterface.check_channel_request>` in the given ``server``
object to allow channels to be opened.
.. note::
After calling this method (or `start_client` or `connect`), you
should no longer directly read from or write to the original socket
object.
:param .threading.Event event:
an event to trigger when negotiation is complete.
:param .ServerInterface server:
an object used to perform authentication and create `channels
<.Channel>`
:raises SSHException: if negotiation fails (and no ``event`` was passed
in)
"""
if server is None:
server = ServerInterface()
self.server_mode = True
self.server_object = server
self.active = True
if event is not None:
# async, return immediately and let the app poll for completion
self.completion_event = event
self.start()
return
# synchronous, wait for a result
self.completion_event = event = threading.Event()
self.start()
while True:
event.wait(0.1)
if not self.active:
e = self.get_exception()
if e is not None:
raise e
raise SSHException('Negotiation failed.')
if event.is_set():
break
def add_server_key(self, key):
"""
Add a host key to the list of keys used for server mode. When behaving
as a server, the host key is used to sign certain packets during the
SSH2 negotiation, so that the client can trust that we are who we say
we are. Because this is used for signing, the key must contain private
key info, not just the public half. Only one key of each type (RSA or
DSS) is kept.
:param .PKey key:
the host key to add, usually an `.RSAKey` or `.DSSKey`.
"""
self.server_key_dict[key.get_name()] = key
def get_server_key(self):
"""
Return the active host key, in server mode. After negotiating with the
client, this method will return the negotiated host key. If only one
type of host key was set with `add_server_key`, that's the only key
that will ever be returned. But in cases where you have set more than
one type of host key (for example, an RSA key and a DSS key), the key
type will be negotiated by the client, and this method will return the
key of the type agreed on. If the host key has not been negotiated
yet, ``None`` is returned. In client mode, the behavior is undefined.
:return:
host key (`.PKey`) of the type negotiated by the client, or
``None``.
"""
try:
return self.server_key_dict[self.host_key_type]
except KeyError:
pass
return None
@staticmethod
def load_server_moduli(filename=None):
"""
(optional)
Load a file of prime moduli for use in doing group-exchange key
negotiation in server mode. It's a rather obscure option and can be
safely ignored.
In server mode, the remote client may request "group-exchange" key
negotiation, which asks the server to send a random prime number that
fits certain criteria. These primes are pretty difficult to compute,
so they can't be generated on demand. But many systems contain a file
of suitable primes (usually named something like ``/etc/ssh/moduli``).
If you call `load_server_moduli` and it returns ``True``, then this
file of primes has been loaded and we will support "group-exchange" in
server mode. Otherwise server mode will just claim that it doesn't
support that method of key negotiation.
:param str filename:
optional path to the moduli file, if you happen to know that it's
not in a standard location.
:return:
True if a moduli file was successfully loaded; False otherwise.
.. note:: This has no effect when used in client mode.
"""
Transport._modulus_pack = ModulusPack()
# places to look for the openssh "moduli" file
file_list = ['/etc/ssh/moduli', '/usr/local/etc/moduli']
if filename is not None:
file_list.insert(0, filename)
for fn in file_list:
try:
Transport._modulus_pack.read_file(fn)
return True
except IOError:
pass
# none succeeded
Transport._modulus_pack = None
return False
def close(self):
"""
Close this session, and any open channels that are tied to it.
"""
if not self.active:
return
self.stop_thread()
for chan in list(self._channels.values()):
chan._unlink()
self.sock.close()
def get_remote_server_key(self):
"""
Return the host key of the server (in client mode).
.. note::
Previously this call returned a tuple of ``(key type, key
string)``. You can get the same effect by calling `.PKey.get_name`
for the key type, and ``str(key)`` for the key string.
:raises SSHException: if no session is currently active.
:return: public key (`.PKey`) of the remote server
"""
if (not self.active) or (not self.initial_kex_done):
raise SSHException('No existing session')
return self.host_key
def is_active(self):
"""
Return true if this session is active (open).
:return:
True if the session is still active (open); False if the session is
closed
"""
return self.active
def open_session(self, window_size=None, max_packet_size=None, timeout=None):
"""
Request a new channel to the server, of type ``"session"``. This is
just an alias for calling `open_channel` with an argument of
``"session"``.
.. note:: Modifying the the window and packet sizes might have adverse
effects on the session created. The default values are the same
as in the OpenSSH code base and have been battle tested.
:param int window_size:
optional window size for this session.
:param int max_packet_size:
optional max packet size for this session.
:return: a new `.Channel`
:raises SSHException: if the request is rejected or the session ends
prematurely
.. versionchanged:: 1.15
Added the ``window_size`` and ``max_packet_size`` arguments.
"""
return self.open_channel('session',
window_size=window_size,
max_packet_size=max_packet_size,
timeout=timeout)
def open_x11_channel(self, src_addr=None):
"""
Request a new channel to the client, of type ``"x11"``. This
is just an alias for ``open_channel('x11', src_addr=src_addr)``.
:param tuple src_addr:
the source address (``(str, int)``) of the x11 server (port is the
x11 port, ie. 6010)
:return: a new `.Channel`
:raises SSHException: if the request is rejected or the session ends
prematurely
"""
return self.open_channel('x11', src_addr=src_addr)
def open_forward_agent_channel(self):
"""
Request a new channel to the client, of type
``"auth-agent@openssh.com"``.
This is just an alias for ``open_channel('auth-agent@openssh.com')``.
:return: a new `.Channel`
:raises SSHException:
if the request is rejected or the session ends prematurely
"""
return self.open_channel('auth-agent@openssh.com')
def open_forwarded_tcpip_channel(self, src_addr, dest_addr):
"""
Request a new channel back to the client, of type ``"forwarded-tcpip"``.
This is used after a client has requested port forwarding, for sending
incoming connections back to the client.
:param src_addr: originator's address
:param dest_addr: local (server) connected address
"""
return self.open_channel('forwarded-tcpip', dest_addr, src_addr)
def open_channel(self,
kind,
dest_addr=None,
src_addr=None,
window_size=None,
max_packet_size=None,
timeout=None):
"""
Request a new channel to the server. `Channels <.Channel>` are
socket-like objects used for the actual transfer of data across the
session. You may only request a channel after negotiating encryption
(using `connect` or `start_client`) and authenticating.
.. note:: Modifying the the window and packet sizes might have adverse
effects on the channel created. The default values are the same
as in the OpenSSH code base and have been battle tested.
:param str kind:
the kind of channel requested (usually ``"session"``,
``"forwarded-tcpip"``, ``"direct-tcpip"``, or ``"x11"``)
:param tuple dest_addr:
the destination address (address + port tuple) of this port
forwarding, if ``kind`` is ``"forwarded-tcpip"`` or
``"direct-tcpip"`` (ignored for other channel types)
:param src_addr: the source address of this port forwarding, if
``kind`` is ``"forwarded-tcpip"``, ``"direct-tcpip"``, or ``"x11"``
:param int window_size:
optional window size for this session.
:param int max_packet_size:
optional max packet size for this session.
:param float timeout:
optional timeout opening a channel, default 3600s (1h)
:return: a new `.Channel` on success
:raises SSHException: if the request is rejected, the session ends
prematurely or there is a timeout openning a channel
.. versionchanged:: 1.15
Added the ``window_size`` and ``max_packet_size`` arguments.
"""
if not self.active:
raise SSHException('SSH session not active')
timeout = 3600 if timeout is None else timeout
self.lock.acquire()
try:
window_size = self._sanitize_window_size(window_size)
max_packet_size = self._sanitize_packet_size(max_packet_size)
chanid = self._next_channel()
m = Message()
m.add_byte(cMSG_CHANNEL_OPEN)
m.add_string(kind)
m.add_int(chanid)
m.add_int(window_size)
m.add_int(max_packet_size)
if (kind == 'forwarded-tcpip') or (kind == 'direct-tcpip'):
m.add_string(dest_addr[0])
m.add_int(dest_addr[1])
m.add_string(src_addr[0])
m.add_int(src_addr[1])
elif kind == 'x11':
m.add_string(src_addr[0])
m.add_int(src_addr[1])
chan = Channel(chanid)
self._channels.put(chanid, chan)
self.channel_events[chanid] = event = threading.Event()
self.channels_seen[chanid] = True
chan._set_transport(self)
chan._set_window(window_size, max_packet_size)
finally:
self.lock.release()
self._send_user_message(m)
start_ts = time.time()
while True:
event.wait(0.1)
if not self.active:
e = self.get_exception()
if e is None:
e = SSHException('Unable to open channel.')
raise e
if event.is_set():
break
elif start_ts + timeout < time.time():
raise SSHException('Timeout openning channel.')
chan = self._channels.get(chanid)
if chan is not None:
return chan
e = self.get_exception()
if e is None:
e = SSHException('Unable to open channel.')
raise e
def request_port_forward(self, address, port, handler=None):
"""
Ask the server to forward TCP connections from a listening port on
the server, across this SSH session.
If a handler is given, that handler is called from a different thread
whenever a forwarded connection arrives. The handler parameters are::
handler(channel, (origin_addr, origin_port), (server_addr, server_port))
where ``server_addr`` and ``server_port`` are the address and port that
the server was listening on.
If no handler is set, the default behavior is to send new incoming
forwarded connections into the accept queue, to be picked up via
`accept`.
:param str address: the address to bind when forwarding
:param int port:
the port to forward, or 0 to ask the server to allocate any port
:param callable handler:
optional handler for incoming forwarded connections, of the form
``func(Channel, (str, int), (str, int))``.
:return: the port number (`int`) allocated by the server
:raises SSHException: if the server refused the TCP forward request
"""
if not self.active:
raise SSHException('SSH session not active')
port = int(port)
response = self.global_request('tcpip-forward', (address, port), wait=True)
if response is None:
raise SSHException('TCP forwarding request denied')
if port == 0:
port = response.get_int()
if handler is None:
def default_handler(channel, src_addr, dest_addr_port):
#src_addr, src_port = src_addr_port
#dest_addr, dest_port = dest_addr_port
self._queue_incoming_channel(channel)
handler = default_handler
self._tcp_handler = handler
return port
def cancel_port_forward(self, address, port):
"""
Ask the server to cancel a previous port-forwarding request. No more
connections to the given address & port will be forwarded across this
ssh connection.
:param str address: the address to stop forwarding
:param int port: the port to stop forwarding
"""
if not self.active:
return
self._tcp_handler = None
self.global_request('cancel-tcpip-forward', (address, port), wait=True)
def open_sftp_client(self):
"""
Create an SFTP client channel from an open transport. On success, an
SFTP session will be opened with the remote host, and a new
`.SFTPClient` object will be returned.
:return:
a new `.SFTPClient` referring to an sftp session (channel) across
this transport
"""
return SFTPClient.from_transport(self)
def send_ignore(self, byte_count=None):
"""
Send a junk packet across the encrypted link. This is sometimes used
to add "noise" to a connection to confuse would-be attackers. It can
also be used as a keep-alive for long lived connections traversing
firewalls.
:param int byte_count:
the number of random bytes to send in the payload of the ignored
packet -- defaults to a random number from 10 to 41.
"""
m = Message()
m.add_byte(cMSG_IGNORE)
if byte_count is None:
byte_count = (byte_ord(os.urandom(1)) % 32) + 10
m.add_bytes(os.urandom(byte_count))
self._send_user_message(m)
def renegotiate_keys(self):
"""
Force this session to switch to new keys. Normally this is done
automatically after the session hits a certain number of packets or
bytes sent or received, but this method gives you the option of forcing
new keys whenever you want. Negotiating new keys causes a pause in
traffic both ways as the two sides swap keys and do computations. This
method returns when the session has switched to new keys.
:raises SSHException: if the key renegotiation failed (which causes the
session to end)
"""
self.completion_event = threading.Event()
self._send_kex_init()
while True:
self.completion_event.wait(0.1)
if not self.active:
e = self.get_exception()
if e is not None:
raise e
raise SSHException('Negotiation failed.')
if self.completion_event.is_set():
break
return
def set_keepalive(self, interval):
"""
Turn on/off keepalive packets (default is off). If this is set, after
``interval`` seconds without sending any data over the connection, a
"keepalive" packet will be sent (and ignored by the remote host). This
can be useful to keep connections alive over a NAT, for example.
:param int interval:
seconds to wait before sending a keepalive packet (or
0 to disable keepalives).
"""
self.packetizer.set_keepalive(interval,
lambda x=weakref.proxy(self): x.global_request('keepalive@lag.net', wait=False))
def global_request(self, kind, data=None, wait=True):
"""
Make a global request to the remote host. These are normally
extensions to the SSH2 protocol.
:param str kind: name of the request.
:param tuple data:
an optional tuple containing additional data to attach to the
request.
:param bool wait:
``True`` if this method should not return until a response is
received; ``False`` otherwise.
:return:
a `.Message` containing possible additional data if the request was
successful (or an empty `.Message` if ``wait`` was ``False``);
``None`` if the request was denied.
"""
if wait:
self.completion_event = threading.Event()
m = Message()
m.add_byte(cMSG_GLOBAL_REQUEST)
m.add_string(kind)
m.add_boolean(wait)
if data is not None:
m.add(*data)
self._log(DEBUG, 'Sending global request "%s"' % kind)
self._send_user_message(m)
if not wait:
return None
while True:
self.completion_event.wait(0.1)
if not self.active:
return None
if self.completion_event.is_set():
break
return self.global_response
def accept(self, timeout=None):
"""
Return the next channel opened by the client over this transport, in
server mode. If no channel is opened before the given timeout, ``None``
is returned.
:param int timeout:
seconds to wait for a channel, or ``None`` to wait forever
:return: a new `.Channel` opened by the client
"""
self.lock.acquire()
try:
if len(self.server_accepts) > 0:
chan = self.server_accepts.pop(0)
else:
self.server_accept_cv.wait(timeout)
if len(self.server_accepts) > 0:
chan = self.server_accepts.pop(0)
else:
# timeout
chan = None
finally:
self.lock.release()
return chan
def connect(self, hostkey=None, username='', password=None, pkey=None,
gss_host=None, gss_auth=False, gss_kex=False, gss_deleg_creds=True):
"""
Negotiate an SSH2 session, and optionally verify the server's host key
and authenticate using a password or private key. This is a shortcut
for `start_client`, `get_remote_server_key`, and
`Transport.auth_password` or `Transport.auth_publickey`. Use those
methods if you want more control.
You can use this method immediately after creating a Transport to
negotiate encryption with a server. If it fails, an exception will be
thrown. On success, the method will return cleanly, and an encrypted
session exists. You may immediately call `open_channel` or
`open_session` to get a `.Channel` object, which is used for data
transfer.
.. note::
If you fail to supply a password or private key, this method may
succeed, but a subsequent `open_channel` or `open_session` call may
fail because you haven't authenticated yet.
:param .PKey hostkey:
the host key expected from the server, or ``None`` if you don't
want to do host key verification.
:param str username: the username to authenticate as.
:param str password:
a password to use for authentication, if you want to use password
authentication; otherwise ``None``.
:param .PKey pkey:
a private key to use for authentication, if you want to use private
key authentication; otherwise ``None``.
:param str gss_host:
The target's name in the kerberos database. Default: hostname
:param bool gss_auth:
``True`` if you want to use GSS-API authentication.
:param bool gss_kex:
Perform GSS-API Key Exchange and user authentication.
:param bool gss_deleg_creds:
Whether to delegate GSS-API client credentials.
:raises SSHException: if the SSH2 negotiation fails, the host key
supplied by the server is incorrect, or authentication fails.
"""
if hostkey is not None:
self._preferred_keys = [hostkey.get_name()]
self.start_client()
# check host key if we were given one
# If GSS-API Key Exchange was performed, we are not required to check
# the host key.
if (hostkey is not None) and not gss_kex:
key = self.get_remote_server_key()
if (key.get_name() != hostkey.get_name()) or (key.asbytes() != hostkey.asbytes()):
self._log(DEBUG, 'Bad host key from server')
self._log(DEBUG, 'Expected: %s: %s' % (hostkey.get_name(), repr(hostkey.asbytes())))
self._log(DEBUG, 'Got : %s: %s' % (key.get_name(), repr(key.asbytes())))
raise SSHException('Bad host key from server')
self._log(DEBUG, 'Host key verified (%s)' % hostkey.get_name())
if (pkey is not None) or (password is not None) or gss_auth or gss_kex:
if gss_auth:
self._log(DEBUG, 'Attempting GSS-API auth... (gssapi-with-mic)')
self.auth_gssapi_with_mic(username, gss_host, gss_deleg_creds)
elif gss_kex:
self._log(DEBUG, 'Attempting GSS-API auth... (gssapi-keyex)')
self.auth_gssapi_keyex(username)
elif pkey is not None:
self._log(DEBUG, 'Attempting public-key auth...')
self.auth_publickey(username, pkey)
else:
self._log(DEBUG, 'Attempting password auth...')
self.auth_password(username, password)
return
def get_exception(self):
"""
Return any exception that happened during the last server request.
This can be used to fetch more specific error information after using
calls like `start_client`. The exception (if any) is cleared after
this call.
:return:
an exception, or ``None`` if there is no stored exception.
.. versionadded:: 1.1
"""
self.lock.acquire()
try:
e = self.saved_exception
self.saved_exception = None
return e
finally:
self.lock.release()
def set_subsystem_handler(self, name, handler, *larg, **kwarg):
"""
Set the handler class for a subsystem in server mode. If a request
for this subsystem is made on an open ssh channel later, this handler
will be constructed and called -- see `.SubsystemHandler` for more
detailed documentation.
Any extra parameters (including keyword arguments) are saved and
passed to the `.SubsystemHandler` constructor later.
:param str name: name of the subsystem.
:param class handler:
subclass of `.SubsystemHandler` that handles this subsystem.
"""
try:
self.lock.acquire()
self.subsystem_table[name] = (handler, larg, kwarg)
finally:
self.lock.release()
def is_authenticated(self):
"""
Return true if this session is active and authenticated.
:return:
True if the session is still open and has been authenticated
successfully; False if authentication failed and/or the session is
closed.
"""
return self.active and (self.auth_handler is not None) and self.auth_handler.is_authenticated()
def get_username(self):
"""
Return the username this connection is authenticated for. If the
session is not authenticated (or authentication failed), this method
returns ``None``.
:return: username that was authenticated (a `str`), or ``None``.
"""
if not self.active or (self.auth_handler is None):
return None
return self.auth_handler.get_username()
def get_banner(self):
"""
Return the banner supplied by the server upon connect. If no banner is
supplied, this method returns ``None``.
:returns: server supplied banner (`str`), or ``None``.
.. versionadded:: 1.13
"""
if not self.active or (self.auth_handler is None):
return None
return self.auth_handler.banner
def auth_none(self, username):
"""
Try to authenticate to the server using no authentication at all.
This will almost always fail. It may be useful for determining the
list of authentication types supported by the server, by catching the
`.BadAuthenticationType` exception raised.
:param str username: the username to authenticate as
:return:
`list` of auth types permissible for the next stage of
authentication (normally empty)
:raises BadAuthenticationType: if "none" authentication isn't allowed
by the server for this user
:raises SSHException: if the authentication failed due to a network
error
.. versionadded:: 1.5
"""
if (not self.active) or (not self.initial_kex_done):
raise SSHException('No existing session')
my_event = threading.Event()
self.auth_handler = AuthHandler(self)
self.auth_handler.auth_none(username, my_event)
return self.auth_handler.wait_for_response(my_event)
def auth_password(self, username, password, event=None, fallback=True):
"""
Authenticate to the server using a password. The username and password
are sent over an encrypted link.
If an ``event`` is passed in, this method will return immediately, and
the event will be triggered once authentication succeeds or fails. On
success, `is_authenticated` will return ``True``. On failure, you may
use `get_exception` to get more detailed error information.
Since 1.1, if no event is passed, this method will block until the
authentication succeeds or fails. On failure, an exception is raised.
Otherwise, the method simply returns.
Since 1.5, if no event is passed and ``fallback`` is ``True`` (the
default), if the server doesn't support plain password authentication
but does support so-called "keyboard-interactive" mode, an attempt
will be made to authenticate using this interactive mode. If it fails,
the normal exception will be thrown as if the attempt had never been
made. This is useful for some recent Gentoo and Debian distributions,
which turn off plain password authentication in a misguided belief
that interactive authentication is "more secure". (It's not.)
If the server requires multi-step authentication (which is very rare),
this method will return a list of auth types permissible for the next
step. Otherwise, in the normal case, an empty list is returned.
:param str username: the username to authenticate as
:param basestring password: the password to authenticate with
:param .threading.Event event:
an event to trigger when the authentication attempt is complete
(whether it was successful or not)
:param bool fallback:
``True`` if an attempt at an automated "interactive" password auth
should be made if the server doesn't support normal password auth
:return:
`list` of auth types permissible for the next stage of
authentication (normally empty)
:raises BadAuthenticationType: if password authentication isn't
allowed by the server for this user (and no event was passed in)
:raises AuthenticationException: if the authentication failed (and no
event was passed in)
:raises SSHException: if there was a network error
"""
if (not self.active) or (not self.initial_kex_done):
# we should never try to send the password unless we're on a secure link
raise SSHException('No existing session')
if event is None:
my_event = threading.Event()
else:
my_event = event
self.auth_handler = AuthHandler(self)
self.auth_handler.auth_password(username, password, my_event)
if event is not None:
# caller wants to wait for event themselves
return []
try:
return self.auth_handler.wait_for_response(my_event)
except BadAuthenticationType as e:
# if password auth isn't allowed, but keyboard-interactive *is*, try to fudge it
if not fallback or ('keyboard-interactive' not in e.allowed_types):
raise
try:
def handler(title, instructions, fields):
if len(fields) > 1:
raise SSHException('Fallback authentication failed.')
if len(fields) == 0:
# for some reason, at least on os x, a 2nd request will
# be made with zero fields requested. maybe it's just
# to try to fake out automated scripting of the exact
# type we're doing here. *shrug* :)
return []
return [password]
return self.auth_interactive(username, handler)
except SSHException:
# attempt failed; just raise the original exception
raise e
def auth_publickey(self, username, key, event=None):
"""
Authenticate to the server using a private key. The key is used to
sign data from the server, so it must include the private part.
If an ``event`` is passed in, this method will return immediately, and
the event will be triggered once authentication succeeds or fails. On
success, `is_authenticated` will return ``True``. On failure, you may
use `get_exception` to get more detailed error information.
Since 1.1, if no event is passed, this method will block until the
authentication succeeds or fails. On failure, an exception is raised.
Otherwise, the method simply returns.
If the server requires multi-step authentication (which is very rare),
this method will return a list of auth types permissible for the next
step. Otherwise, in the normal case, an empty list is returned.
:param str username: the username to authenticate as
:param .PKey key: the private key to authenticate with
:param .threading.Event event:
an event to trigger when the authentication attempt is complete
(whether it was successful or not)
:return:
`list` of auth types permissible for the next stage of
authentication (normally empty)
:raises BadAuthenticationType: if public-key authentication isn't
allowed by the server for this user (and no event was passed in)
:raises AuthenticationException: if the authentication failed (and no
event was passed in)
:raises SSHException: if there was a network error
"""
if (not self.active) or (not self.initial_kex_done):
# we should never try to authenticate unless we're on a secure link
raise SSHException('No existing session')
if event is None:
my_event = threading.Event()
else:
my_event = event
self.auth_handler = AuthHandler(self)
self.auth_handler.auth_publickey(username, key, my_event)
if event is not None:
# caller wants to wait for event themselves
return []
return self.auth_handler.wait_for_response(my_event)
def auth_interactive(self, username, handler, submethods=''):
"""
Authenticate to the server interactively. A handler is used to answer
arbitrary questions from the server. On many servers, this is just a
dumb wrapper around PAM.
This method will block until the authentication succeeds or fails,
peroidically calling the handler asynchronously to get answers to
authentication questions. The handler may be called more than once
if the server continues to ask questions.
The handler is expected to be a callable that will handle calls of the
form: ``handler(title, instructions, prompt_list)``. The ``title`` is
meant to be a dialog-window title, and the ``instructions`` are user
instructions (both are strings). ``prompt_list`` will be a list of
prompts, each prompt being a tuple of ``(str, bool)``. The string is
the prompt and the boolean indicates whether the user text should be
echoed.
A sample call would thus be:
``handler('title', 'instructions', [('Password:', False)])``.
The handler should return a list or tuple of answers to the server's
questions.
If the server requires multi-step authentication (which is very rare),
this method will return a list of auth types permissible for the next
step. Otherwise, in the normal case, an empty list is returned.
:param str username: the username to authenticate as
:param callable handler: a handler for responding to server questions
:param str submethods: a string list of desired submethods (optional)
:return:
`list` of auth types permissible for the next stage of
authentication (normally empty).
:raises BadAuthenticationType: if public-key authentication isn't
allowed by the server for this user
:raises AuthenticationException: if the authentication failed
:raises SSHException: if there was a network error
.. versionadded:: 1.5
"""
if (not self.active) or (not self.initial_kex_done):
# we should never try to authenticate unless we're on a secure link
raise SSHException('No existing session')
my_event = threading.Event()
self.auth_handler = AuthHandler(self)
self.auth_handler.auth_interactive(username, handler, my_event, submethods)
return self.auth_handler.wait_for_response(my_event)
def auth_interactive_dumb(self, username, handler=None, submethods=''):
"""
Autenticate to the server interactively but dumber.
Just print the prompt and / or instructions to stdout and send back
the response. This is good for situations where partial auth is
achieved by key and then the user has to enter a 2fac token.
"""
if not handler:
def handler(title, instructions, prompt_list):
answers = []
if title:
print(title.strip())
if instructions:
print(instructions.strip())
for prompt,show_input in prompt_list:
print(prompt.strip(),end=' ')
answers.append(input())
return answers
return self.auth_interactive(username, handler, submethods)
def auth_gssapi_with_mic(self, username, gss_host, gss_deleg_creds):
"""
Authenticate to the Server using GSS-API / SSPI.
:param str username: The username to authenticate as
:param str gss_host: The target host
:param bool gss_deleg_creds: Delegate credentials or not
:return: list of auth types permissible for the next stage of
authentication (normally empty)
:rtype: list
:raise BadAuthenticationType: if gssapi-with-mic isn't
allowed by the server (and no event was passed in)
:raise AuthenticationException: if the authentication failed (and no
event was passed in)
:raise SSHException: if there was a network error
"""
if (not self.active) or (not self.initial_kex_done):
# we should never try to authenticate unless we're on a secure link
raise SSHException('No existing session')
my_event = threading.Event()
self.auth_handler = AuthHandler(self)
self.auth_handler.auth_gssapi_with_mic(username, gss_host, gss_deleg_creds, my_event)
return self.auth_handler.wait_for_response(my_event)
def auth_gssapi_keyex(self, username):
"""
Authenticate to the Server with GSS-API / SSPI if GSS-API Key Exchange
was the used key exchange method.
:param str username: The username to authenticate as
:param str gss_host: The target host
:param bool gss_deleg_creds: Delegate credentials or not
:return: list of auth types permissible for the next stage of
authentication (normally empty)
:rtype: list
:raise BadAuthenticationType: if GSS-API Key Exchange was not performed
(and no event was passed in)
:raise AuthenticationException: if the authentication failed (and no
event was passed in)
:raise SSHException: if there was a network error
"""
if (not self.active) or (not self.initial_kex_done):
# we should never try to authenticate unless we're on a secure link
raise SSHException('No existing session')
my_event = threading.Event()
self.auth_handler = AuthHandler(self)
self.auth_handler.auth_gssapi_keyex(username, my_event)
return self.auth_handler.wait_for_response(my_event)
def set_log_channel(self, name):
"""
Set the channel for this transport's logging. The default is
``"paramiko.transport"`` but it can be set to anything you want. (See
the `.logging` module for more info.) SSH Channels will log to a
sub-channel of the one specified.
:param str name: new channel name for logging
.. versionadded:: 1.1
"""
self.log_name = name
self.logger = util.get_logger(name)
self.packetizer.set_log(self.logger)
def get_log_channel(self):
"""
Return the channel name used for this transport's logging.
:return: channel name as a `str`
.. versionadded:: 1.2
"""
return self.log_name
def set_hexdump(self, hexdump):
"""
Turn on/off logging a hex dump of protocol traffic at DEBUG level in
the logs. Normally you would want this off (which is the default),
but if you are debugging something, it may be useful.
:param bool hexdump:
``True`` to log protocol traffix (in hex) to the log; ``False``
otherwise.
"""
self.packetizer.set_hexdump(hexdump)
def get_hexdump(self):
"""
Return ``True`` if the transport is currently logging hex dumps of
protocol traffic.
:return: ``True`` if hex dumps are being logged, else ``False``.
.. versionadded:: 1.4
"""
return self.packetizer.get_hexdump()
def use_compression(self, compress=True):
"""
Turn on/off compression. This will only have an affect before starting
the transport (ie before calling `connect`, etc). By default,
compression is off since it negatively affects interactive sessions.
:param bool compress:
``True`` to ask the remote client/server to compress traffic;
``False`` to refuse compression
.. versionadded:: 1.5.2
"""
if compress:
self._preferred_compression = ('zlib@openssh.com', 'zlib', 'none')
else:
self._preferred_compression = ('none',)
def getpeername(self):
"""
Return the address of the remote side of this Transport, if possible.
This is effectively a wrapper around ``'getpeername'`` on the underlying
socket. If the socket-like object has no ``'getpeername'`` method,
then ``("unknown", 0)`` is returned.
:return:
the address of the remote host, if known, as a ``(str, int)``
tuple.
"""
gp = getattr(self.sock, 'getpeername', None)
if gp is None:
return 'unknown', 0
return gp()
def stop_thread(self):
self.active = False
self.packetizer.close()
while self.is_alive() and (self is not threading.current_thread()):
self.join(10)
### internals...
def _log(self, level, msg, *args):
if issubclass(type(msg), list):
for m in msg:
self.logger.log(level, m)
else:
self.logger.log(level, msg, *args)
def _get_modulus_pack(self):
"""used by KexGex to find primes for group exchange"""
return self._modulus_pack
def _next_channel(self):
"""you are holding the lock"""
chanid = self._channel_counter
while self._channels.get(chanid) is not None:
self._channel_counter = (self._channel_counter + 1) & 0xffffff
chanid = self._channel_counter
self._channel_counter = (self._channel_counter + 1) & 0xffffff
return chanid
def _unlink_channel(self, chanid):
"""used by a Channel to remove itself from the active channel list"""
self._channels.delete(chanid)
def _send_message(self, data):
self.packetizer.send_message(data)
def _send_user_message(self, data):
"""
send a message, but block if we're in key negotiation. this is used
for user-initiated requests.
"""
start = time.time()
while True:
self.clear_to_send.wait(0.1)
if not self.active:
self._log(DEBUG, 'Dropping user packet because connection is dead.')
return
self.clear_to_send_lock.acquire()
if self.clear_to_send.is_set():
break
self.clear_to_send_lock.release()
if time.time() > start + self.clear_to_send_timeout:
raise SSHException('Key-exchange timed out waiting for key negotiation')
try:
self._send_message(data)
finally:
self.clear_to_send_lock.release()
def _set_K_H(self, k, h):
"""used by a kex object to set the K (root key) and H (exchange hash)"""
self.K = k
self.H = h
if self.session_id is None:
self.session_id = h
def _expect_packet(self, *ptypes):
"""used by a kex object to register the next packet type it expects to see"""
self._expected_packet = tuple(ptypes)
def _verify_key(self, host_key, sig):
key = self._key_info[self.host_key_type](Message(host_key))
if key is None:
raise SSHException('Unknown host key type')
if not key.verify_ssh_sig(self.H, Message(sig)):
raise SSHException('Signature verification (%s) failed.' % self.host_key_type)
self.host_key = key
def _compute_key(self, id, nbytes):
"""id is 'A' - 'F' for the various keys used by ssh"""
m = Message()
m.add_mpint(self.K)
m.add_bytes(self.H)
m.add_byte(b(id))
m.add_bytes(self.session_id)
# Fallback to SHA1 for kex engines that fail to specify a hex
# algorithm, or for e.g. transport tests that don't run kexinit.
hash_algo = getattr(self.kex_engine, 'hash_algo', None)
hash_select_msg = "kex engine %s specified hash_algo %r" % (self.kex_engine.__class__.__name__, hash_algo)
if hash_algo is None:
hash_algo = sha1
hash_select_msg += ", falling back to sha1"
if not hasattr(self, '_logged_hash_selection'):
self._log(DEBUG, hash_select_msg)
setattr(self, '_logged_hash_selection', True)
out = sofar = hash_algo(m.asbytes()).digest()
while len(out) < nbytes:
m = Message()
m.add_mpint(self.K)
m.add_bytes(self.H)
m.add_bytes(sofar)
digest = hash_algo(m.asbytes()).digest()
out += digest
sofar += digest
return out[:nbytes]
def _get_cipher(self, name, key, iv, operation):
if name not in self._cipher_info:
raise SSHException('Unknown client cipher ' + name)
if name in ('arcfour128', 'arcfour256'):
# arcfour cipher
cipher = Cipher(
self._cipher_info[name]['class'](key),
None,
backend=default_backend()
)
if operation is self._ENCRYPT:
engine = cipher.encryptor()
else:
engine = cipher.decryptor()
# as per RFC 4345, the first 1536 bytes of keystream
# generated by the cipher MUST be discarded
engine.encrypt(" " * 1536)
return engine
else:
cipher = Cipher(
self._cipher_info[name]['class'](key),
self._cipher_info[name]['mode'](iv),
backend=default_backend(),
)
if operation is self._ENCRYPT:
return cipher.encryptor()
else:
return cipher.decryptor()
def _set_forward_agent_handler(self, handler):
if handler is None:
def default_handler(channel):
self._queue_incoming_channel(channel)
self._forward_agent_handler = default_handler
else:
self._forward_agent_handler = handler
def _set_x11_handler(self, handler):
# only called if a channel has turned on x11 forwarding
if handler is None:
# by default, use the same mechanism as accept()
def default_handler(channel, src_addr_port):
self._queue_incoming_channel(channel)
self._x11_handler = default_handler
else:
self._x11_handler = handler
def _queue_incoming_channel(self, channel):
self.lock.acquire()
try:
self.server_accepts.append(channel)
self.server_accept_cv.notify()
finally:
self.lock.release()
def _sanitize_window_size(self, window_size):
if window_size is None:
window_size = self.default_window_size
return clamp_value(MIN_WINDOW_SIZE, window_size, MAX_WINDOW_SIZE)
def _sanitize_packet_size(self, max_packet_size):
if max_packet_size is None:
max_packet_size = self.default_max_packet_size
return clamp_value(MIN_PACKET_SIZE, max_packet_size, MAX_WINDOW_SIZE)
def _ensure_authed(self, ptype, message):
"""
Checks message type against current auth state.
If server mode, and auth has not succeeded, and the message is of a
post-auth type (channel open or global request) an appropriate error
response Message is crafted and returned to caller for sending.
Otherwise (client mode, authed, or pre-auth message) returns None.
"""
if (
not self.server_mode
or ptype <= HIGHEST_USERAUTH_MESSAGE_ID
or self.is_authenticated()
):
return None
# WELP. We must be dealing with someone trying to do non-auth things
# without being authed. Tell them off, based on message class.
reply = Message()
# Global requests have no details, just failure.
if ptype == MSG_GLOBAL_REQUEST:
reply.add_byte(cMSG_REQUEST_FAILURE)
# Channel opens let us reject w/ a specific type + message.
elif ptype == MSG_CHANNEL_OPEN:
kind = message.get_text()
chanid = message.get_int()
reply.add_byte(cMSG_CHANNEL_OPEN_FAILURE)
reply.add_int(chanid)
reply.add_int(OPEN_FAILED_ADMINISTRATIVELY_PROHIBITED)
reply.add_string('')
reply.add_string('en')
# NOTE: Post-open channel messages do not need checking; the above will
# reject attemps to open channels, meaning that even if a malicious
# user tries to send a MSG_CHANNEL_REQUEST, it will simply fall under
# the logic that handles unknown channel IDs (as the channel list will
# be empty.)
return reply
def run(self):
# (use the exposed "run" method, because if we specify a thread target
# of a private method, threading.Thread will keep a reference to it
# indefinitely, creating a GC cycle and not letting Transport ever be
# GC'd. it's a bug in Thread.)
# Hold reference to 'sys' so we can test sys.modules to detect
# interpreter shutdown.
self.sys = sys
# active=True occurs before the thread is launched, to avoid a race
_active_threads.append(self)
if self.server_mode:
self._log(DEBUG, 'starting thread (server mode): %s' % hex(long(id(self)) & xffffffff))
else:
self._log(DEBUG, 'starting thread (client mode): %s' % hex(long(id(self)) & xffffffff))
try:
try:
self.packetizer.write_all(b(self.local_version + '\r\n'))
self._log(DEBUG, 'Local version/idstring: %s' % self.local_version)
self._check_banner()
# The above is actually very much part of the handshake, but
# sometimes the banner can be read but the machine is not
# responding, for example when the remote ssh daemon is loaded
# in to memory but we can not read from the disk/spawn a new
# shell.
# Make sure we can specify a timeout for the initial handshake.
# Re-use the banner timeout for now.
self.packetizer.start_handshake(self.handshake_timeout)
self._send_kex_init()
self._expect_packet(MSG_KEXINIT)
while self.active:
if self.packetizer.need_rekey() and not self.in_kex:
self._send_kex_init()
try:
ptype, m = self.packetizer.read_message()
except NeedRekeyException:
continue
if ptype == MSG_IGNORE:
continue
elif ptype == MSG_DISCONNECT:
self._parse_disconnect(m)
self.active = False
self.packetizer.close()
break
elif ptype == MSG_DEBUG:
self._parse_debug(m)
continue
if len(self._expected_packet) > 0:
if ptype not in self._expected_packet:
raise SSHException('Expecting packet from %r, got %d' % (self._expected_packet, ptype))
self._expected_packet = tuple()
if (ptype >= 30) and (ptype <= 41):
self.kex_engine.parse_next(ptype, m)
continue
if ptype in self._handler_table:
error_msg = self._ensure_authed(ptype, m)
if error_msg:
self._send_message(error_msg)
else:
self._handler_table[ptype](self, m)
elif ptype in self._channel_handler_table:
chanid = m.get_int()
chan = self._channels.get(chanid)
if chan is not None:
self._channel_handler_table[ptype](chan, m)
elif chanid in self.channels_seen:
self._log(DEBUG, 'Ignoring message for dead channel %d' % chanid)
else:
self._log(ERROR, 'Channel request for unknown channel %d' % chanid)
self.active = False
self.packetizer.close()
elif (self.auth_handler is not None) and (ptype in self.auth_handler._handler_table):
self.auth_handler._handler_table[ptype](self.auth_handler, m)
else:
# Respond with "I don't implement this particular
# message type" message (unless the message type was
# itself literally MSG_UNIMPLEMENTED, in which case, we
# just shut up to avoid causing a useless loop).
name = MSG_NAMES[ptype]
self._log(
WARNING,
"Oops, unhandled type {} ({!r})".format(
ptype, name
),
)
if ptype != MSG_UNIMPLEMENTED:
msg = Message()
msg.add_byte(cMSG_UNIMPLEMENTED)
msg.add_int(m.seqno)
self._send_message(msg)
self.packetizer.complete_handshake()
except SSHException as e:
self._log(ERROR, 'Exception: ' + str(e))
self._log(ERROR, util.tb_strings())
self.saved_exception = e
except EOFError as e:
self._log(DEBUG, 'EOF in transport thread')
#self._log(DEBUG, util.tb_strings())
self.saved_exception = e
except socket.error as e:
if type(e.args) is tuple:
if e.args:
emsg = '%s (%d)' % (e.args[1], e.args[0])
else: # empty tuple, e.g. socket.timeout
emsg = str(e) or repr(e)
else:
emsg = e.args
self._log(ERROR, 'Socket exception: ' + emsg)
self.saved_exception = e
except Exception as e:
self._log(ERROR, 'Unknown exception: ' + str(e))
self._log(ERROR, util.tb_strings())
self.saved_exception = e
_active_threads.remove(self)
for chan in list(self._channels.values()):
chan._unlink()
if self.active:
self.active = False
self.packetizer.close()
if self.completion_event is not None:
self.completion_event.set()
if self.auth_handler is not None:
self.auth_handler.abort()
for event in self.channel_events.values():
event.set()
try:
self.lock.acquire()
self.server_accept_cv.notify()
finally:
self.lock.release()
self.sock.close()
except:
# Don't raise spurious 'NoneType has no attribute X' errors when we
# wake up during interpreter shutdown. Or rather -- raise
# everything *if* sys.modules (used as a convenient sentinel)
# appears to still exist.
if self.sys.modules is not None:
raise
def _log_agreement(self, which, local, remote):
# Log useful, non-duplicative line re: an agreed-upon algorithm.
# Old code implied algorithms could be asymmetrical (different for
# inbound vs outbound) so we preserve that possibility.
msg = "{0} agreed: ".format(which)
if local == remote:
msg += local
else:
msg += "local={0}, remote={1}".format(local, remote)
self._log(DEBUG, msg)
### protocol stages
def _negotiate_keys(self, m):
# throws SSHException on anything unusual
self.clear_to_send_lock.acquire()
try:
self.clear_to_send.clear()
finally:
self.clear_to_send_lock.release()
if self.local_kex_init is None:
# remote side wants to renegotiate
self._send_kex_init()
self._parse_kex_init(m)
self.kex_engine.start_kex()
def _check_banner(self):
# this is slow, but we only have to do it once
for i in range(100):
# give them 15 seconds for the first line, then just 2 seconds
# each additional line. (some sites have very high latency.)
if i == 0:
timeout = self.banner_timeout
else:
timeout = 2
try:
buf = self.packetizer.readline(timeout)
except ProxyCommandFailure:
raise
except Exception as e:
raise SSHException('Error reading SSH protocol banner' + str(e))
if buf[:4] == 'SSH-':
break
self._log(DEBUG, 'Banner: ' + buf)
if buf[:4] != 'SSH-':
raise SSHException('Indecipherable protocol version "' + buf + '"')
# save this server version string for later
self.remote_version = buf
self._log(DEBUG, 'Remote version/idstring: %s' % buf)
# pull off any attached comment
comment = ''
i = buf.find(' ')
if i >= 0:
comment = buf[i+1:]
buf = buf[:i]
# parse out version string and make sure it matches
segs = buf.split('-', 2)
if len(segs) < 3:
raise SSHException('Invalid SSH banner')
version = segs[1]
client = segs[2]
if version != '1.99' and version != '2.0':
raise SSHException('Incompatible version (%s instead of 2.0)' % (version,))
self._log(INFO, 'Connected (version %s, client %s)' % (version, client))
def _send_kex_init(self):
"""
announce to the other side that we'd like to negotiate keys, and what
kind of key negotiation we support.
"""
self.clear_to_send_lock.acquire()
try:
self.clear_to_send.clear()
finally:
self.clear_to_send_lock.release()
self.in_kex = True
if self.server_mode:
mp_required_prefix = 'diffie-hellman-group-exchange-sha'
kex_mp = [k for k in self._preferred_kex if k.startswith(mp_required_prefix)]
if (self._modulus_pack is None) and (len(kex_mp) > 0):
# can't do group-exchange if we don't have a pack of potential primes
pkex = [k for k in self.get_security_options().kex
if not k.startswith(mp_required_prefix)]
self.get_security_options().kex = pkex
available_server_keys = list(filter(list(self.server_key_dict.keys()).__contains__,
self._preferred_keys))
else:
available_server_keys = self._preferred_keys
m = Message()
m.add_byte(cMSG_KEXINIT)
m.add_bytes(os.urandom(16))
m.add_list(self._preferred_kex)
m.add_list(available_server_keys)
m.add_list(self._preferred_ciphers)
m.add_list(self._preferred_ciphers)
m.add_list(self._preferred_macs)
m.add_list(self._preferred_macs)
m.add_list(self._preferred_compression)
m.add_list(self._preferred_compression)
m.add_string(bytes())
m.add_string(bytes())
m.add_boolean(False)
m.add_int(0)
# save a copy for later (needed to compute a hash)
self.local_kex_init = m.asbytes()
self._send_message(m)
def _parse_kex_init(self, m):
cookie = m.get_bytes(16)
kex_algo_list = m.get_list()
server_key_algo_list = m.get_list()
client_encrypt_algo_list = m.get_list()
server_encrypt_algo_list = m.get_list()
client_mac_algo_list = m.get_list()
server_mac_algo_list = m.get_list()
client_compress_algo_list = m.get_list()
server_compress_algo_list = m.get_list()
client_lang_list = m.get_list()
server_lang_list = m.get_list()
kex_follows = m.get_boolean()
unused = m.get_int()
self._log(DEBUG, 'kex algos:' + str(kex_algo_list) + ' server key:' + str(server_key_algo_list) +
' client encrypt:' + str(client_encrypt_algo_list) +
' server encrypt:' + str(server_encrypt_algo_list) +
' client mac:' + str(client_mac_algo_list) +
' server mac:' + str(server_mac_algo_list) +
' client compress:' + str(client_compress_algo_list) +
' server compress:' + str(server_compress_algo_list) +
' client lang:' + str(client_lang_list) +
' server lang:' + str(server_lang_list) +
' kex follows?' + str(kex_follows))
# as a server, we pick the first item in the client's list that we
# support.
# as a client, we pick the first item in our list that the server
# supports.
if self.server_mode:
agreed_kex = list(filter(
self._preferred_kex.__contains__,
kex_algo_list
))
else:
agreed_kex = list(filter(
kex_algo_list.__contains__,
self._preferred_kex
))
if len(agreed_kex) == 0:
raise SSHException('Incompatible ssh peer (no acceptable kex algorithm)')
self.kex_engine = self._kex_info[agreed_kex[0]](self)
self._log(DEBUG, "Kex agreed: %s" % agreed_kex[0])
if self.server_mode:
available_server_keys = list(filter(list(self.server_key_dict.keys()).__contains__,
self._preferred_keys))
agreed_keys = list(filter(available_server_keys.__contains__, server_key_algo_list))
else:
agreed_keys = list(filter(server_key_algo_list.__contains__, self._preferred_keys))
if len(agreed_keys) == 0:
raise SSHException('Incompatible ssh peer (no acceptable host key)')
self.host_key_type = agreed_keys[0]
if self.server_mode and (self.get_server_key() is None):
raise SSHException('Incompatible ssh peer (can\'t match requested host key type)')
if self.server_mode:
agreed_local_ciphers = list(filter(self._preferred_ciphers.__contains__,
server_encrypt_algo_list))
agreed_remote_ciphers = list(filter(self._preferred_ciphers.__contains__,
client_encrypt_algo_list))
else:
agreed_local_ciphers = list(filter(client_encrypt_algo_list.__contains__,
self._preferred_ciphers))
agreed_remote_ciphers = list(filter(server_encrypt_algo_list.__contains__,
self._preferred_ciphers))
if (len(agreed_local_ciphers) == 0) or (len(agreed_remote_ciphers) == 0):
raise SSHException('Incompatible ssh server (no acceptable ciphers)')
self.local_cipher = agreed_local_ciphers[0]
self.remote_cipher = agreed_remote_ciphers[0]
self._log_agreement(
'Cipher', local=self.local_cipher, remote=self.remote_cipher
)
if self.server_mode:
agreed_remote_macs = list(filter(self._preferred_macs.__contains__, client_mac_algo_list))
agreed_local_macs = list(filter(self._preferred_macs.__contains__, server_mac_algo_list))
else:
agreed_local_macs = list(filter(client_mac_algo_list.__contains__, self._preferred_macs))
agreed_remote_macs = list(filter(server_mac_algo_list.__contains__, self._preferred_macs))
if (len(agreed_local_macs) == 0) or (len(agreed_remote_macs) == 0):
raise SSHException('Incompatible ssh server (no acceptable macs)')
self.local_mac = agreed_local_macs[0]
self.remote_mac = agreed_remote_macs[0]
self._log_agreement(
'MAC', local=self.local_mac, remote=self.remote_mac
)
if self.server_mode:
agreed_remote_compression = list(filter(self._preferred_compression.__contains__, client_compress_algo_list))
agreed_local_compression = list(filter(self._preferred_compression.__contains__, server_compress_algo_list))
else:
agreed_local_compression = list(filter(client_compress_algo_list.__contains__, self._preferred_compression))
agreed_remote_compression = list(filter(server_compress_algo_list.__contains__, self._preferred_compression))
if (len(agreed_local_compression) == 0) or (len(agreed_remote_compression) == 0):
raise SSHException('Incompatible ssh server (no acceptable compression) %r %r %r' % (agreed_local_compression, agreed_remote_compression, self._preferred_compression))
self.local_compression = agreed_local_compression[0]
self.remote_compression = agreed_remote_compression[0]
self._log_agreement(
'Compression',
local=self.local_compression,
remote=self.remote_compression
)
# save for computing hash later...
# now wait! openssh has a bug (and others might too) where there are
# actually some extra bytes (one NUL byte in openssh's case) added to
# the end of the packet but not parsed. turns out we need to throw
# away those bytes because they aren't part of the hash.
self.remote_kex_init = cMSG_KEXINIT + m.get_so_far()
def _activate_inbound(self):
"""switch on newly negotiated encryption parameters for inbound traffic"""
block_size = self._cipher_info[self.remote_cipher]['block-size']
if self.server_mode:
IV_in = self._compute_key('A', block_size)
key_in = self._compute_key('C', self._cipher_info[self.remote_cipher]['key-size'])
else:
IV_in = self._compute_key('B', block_size)
key_in = self._compute_key('D', self._cipher_info[self.remote_cipher]['key-size'])
engine = self._get_cipher(self.remote_cipher, key_in, IV_in, self._DECRYPT)
mac_size = self._mac_info[self.remote_mac]['size']
mac_engine = self._mac_info[self.remote_mac]['class']
# initial mac keys are done in the hash's natural size (not the
# potentially truncated transmission size)
if self.server_mode:
mac_key = self._compute_key('E', mac_engine().digest_size)
else:
mac_key = self._compute_key('F', mac_engine().digest_size)
self.packetizer.set_inbound_cipher(engine, block_size, mac_engine, mac_size, mac_key)
compress_in = self._compression_info[self.remote_compression][1]
if (compress_in is not None) and ((self.remote_compression != 'zlib@openssh.com') or self.authenticated):
self._log(DEBUG, 'Switching on inbound compression ...')
self.packetizer.set_inbound_compressor(compress_in())
def _activate_outbound(self):
"""switch on newly negotiated encryption parameters for outbound traffic"""
m = Message()
m.add_byte(cMSG_NEWKEYS)
self._send_message(m)
block_size = self._cipher_info[self.local_cipher]['block-size']
if self.server_mode:
IV_out = self._compute_key('B', block_size)
key_out = self._compute_key('D', self._cipher_info[self.local_cipher]['key-size'])
else:
IV_out = self._compute_key('A', block_size)
key_out = self._compute_key('C', self._cipher_info[self.local_cipher]['key-size'])
engine = self._get_cipher(self.local_cipher, key_out, IV_out, self._ENCRYPT)
mac_size = self._mac_info[self.local_mac]['size']
mac_engine = self._mac_info[self.local_mac]['class']
# initial mac keys are done in the hash's natural size (not the
# potentially truncated transmission size)
if self.server_mode:
mac_key = self._compute_key('F', mac_engine().digest_size)
else:
mac_key = self._compute_key('E', mac_engine().digest_size)
sdctr = self.local_cipher.endswith('-ctr')
self.packetizer.set_outbound_cipher(engine, block_size, mac_engine, mac_size, mac_key, sdctr)
compress_out = self._compression_info[self.local_compression][0]
if (compress_out is not None) and ((self.local_compression != 'zlib@openssh.com') or self.authenticated):
self._log(DEBUG, 'Switching on outbound compression ...')
self.packetizer.set_outbound_compressor(compress_out())
if not self.packetizer.need_rekey():
self.in_kex = False
# we always expect to receive NEWKEYS now
self._expect_packet(MSG_NEWKEYS)
def _auth_trigger(self):
self.authenticated = True
# delayed initiation of compression
if self.local_compression == 'zlib@openssh.com':
compress_out = self._compression_info[self.local_compression][0]
self._log(DEBUG, 'Switching on outbound compression ...')
self.packetizer.set_outbound_compressor(compress_out())
if self.remote_compression == 'zlib@openssh.com':
compress_in = self._compression_info[self.remote_compression][1]
self._log(DEBUG, 'Switching on inbound compression ...')
self.packetizer.set_inbound_compressor(compress_in())
def _parse_newkeys(self, m):
self._log(DEBUG, 'Switch to new keys ...')
self._activate_inbound()
# can also free a bunch of stuff here
self.local_kex_init = self.remote_kex_init = None
self.K = None
self.kex_engine = None
if self.server_mode and (self.auth_handler is None):
# create auth handler for server mode
self.auth_handler = AuthHandler(self)
if not self.initial_kex_done:
# this was the first key exchange
self.initial_kex_done = True
# send an event?
if self.completion_event is not None:
self.completion_event.set()
# it's now okay to send data again (if this was a re-key)
if not self.packetizer.need_rekey():
self.in_kex = False
self.clear_to_send_lock.acquire()
try:
self.clear_to_send.set()
finally:
self.clear_to_send_lock.release()
return
def _parse_disconnect(self, m):
code = m.get_int()
desc = m.get_text()
self._log(INFO, 'Disconnect (code %d): %s' % (code, desc))
def _parse_global_request(self, m):
kind = m.get_text()
self._log(DEBUG, 'Received global request "%s"' % kind)
want_reply = m.get_boolean()
if not self.server_mode:
self._log(DEBUG, 'Rejecting "%s" global request from server.' % kind)
ok = False
elif kind == 'tcpip-forward':
address = m.get_text()
port = m.get_int()
ok = self.server_object.check_port_forward_request(address, port)
if ok:
ok = (ok,)
elif kind == 'cancel-tcpip-forward':
address = m.get_text()
port = m.get_int()
self.server_object.cancel_port_forward_request(address, port)
ok = True
else:
ok = self.server_object.check_global_request(kind, m)
extra = ()
if type(ok) is tuple:
extra = ok
ok = True
if want_reply:
msg = Message()
if ok:
msg.add_byte(cMSG_REQUEST_SUCCESS)
msg.add(*extra)
else:
msg.add_byte(cMSG_REQUEST_FAILURE)
self._send_message(msg)
def _parse_request_success(self, m):
self._log(DEBUG, 'Global request successful.')
self.global_response = m
if self.completion_event is not None:
self.completion_event.set()
def _parse_request_failure(self, m):
self._log(DEBUG, 'Global request denied.')
self.global_response = None
if self.completion_event is not None:
self.completion_event.set()
def _parse_channel_open_success(self, m):
chanid = m.get_int()
server_chanid = m.get_int()
server_window_size = m.get_int()
server_max_packet_size = m.get_int()
chan = self._channels.get(chanid)
if chan is None:
self._log(WARNING, 'Success for unrequested channel! [??]')
return
self.lock.acquire()
try:
chan._set_remote_channel(server_chanid, server_window_size, server_max_packet_size)
self._log(DEBUG, 'Secsh channel %d opened.' % chanid)
if chanid in self.channel_events:
self.channel_events[chanid].set()
del self.channel_events[chanid]
finally:
self.lock.release()
return
def _parse_channel_open_failure(self, m):
chanid = m.get_int()
reason = m.get_int()
reason_str = m.get_text()
lang = m.get_text()
reason_text = CONNECTION_FAILED_CODE.get(reason, '(unknown code)')
self._log(ERROR, 'Secsh channel %d open FAILED: %s: %s' % (chanid, reason_str, reason_text))
self.lock.acquire()
try:
self.saved_exception = ChannelException(reason, reason_text)
if chanid in self.channel_events:
self._channels.delete(chanid)
if chanid in self.channel_events:
self.channel_events[chanid].set()
del self.channel_events[chanid]
finally:
self.lock.release()
return
def _parse_channel_open(self, m):
kind = m.get_text()
chanid = m.get_int()
initial_window_size = m.get_int()
max_packet_size = m.get_int()
reject = False
if (kind == 'auth-agent@openssh.com') and (self._forward_agent_handler is not None):
self._log(DEBUG, 'Incoming forward agent connection')
self.lock.acquire()
try:
my_chanid = self._next_channel()
finally:
self.lock.release()
elif (kind == 'x11') and (self._x11_handler is not None):
origin_addr = m.get_text()
origin_port = m.get_int()
self._log(DEBUG, 'Incoming x11 connection from %s:%d' % (origin_addr, origin_port))
self.lock.acquire()
try:
my_chanid = self._next_channel()
finally:
self.lock.release()
elif (kind == 'forwarded-tcpip') and (self._tcp_handler is not None):
server_addr = m.get_text()
server_port = m.get_int()
origin_addr = m.get_text()
origin_port = m.get_int()
self._log(DEBUG, 'Incoming tcp forwarded connection from %s:%d' % (origin_addr, origin_port))
self.lock.acquire()
try:
my_chanid = self._next_channel()
finally:
self.lock.release()
elif not self.server_mode:
self._log(DEBUG, 'Rejecting "%s" channel request from server.' % kind)
reject = True
reason = OPEN_FAILED_ADMINISTRATIVELY_PROHIBITED
else:
self.lock.acquire()
try:
my_chanid = self._next_channel()
finally:
self.lock.release()
if kind == 'direct-tcpip':
# handle direct-tcpip requests comming from the client
dest_addr = m.get_text()
dest_port = m.get_int()
origin_addr = m.get_text()
origin_port = m.get_int()
reason = self.server_object.check_channel_direct_tcpip_request(
my_chanid, (origin_addr, origin_port), (dest_addr, dest_port))
else:
reason = self.server_object.check_channel_request(kind, my_chanid)
if reason != OPEN_SUCCEEDED:
self._log(DEBUG, 'Rejecting "%s" channel request from client.' % kind)
reject = True
if reject:
msg = Message()
msg.add_byte(cMSG_CHANNEL_OPEN_FAILURE)
msg.add_int(chanid)
msg.add_int(reason)
msg.add_string('')
msg.add_string('en')
self._send_message(msg)
return
chan = Channel(my_chanid)
self.lock.acquire()
try:
self._channels.put(my_chanid, chan)
self.channels_seen[my_chanid] = True
chan._set_transport(self)
chan._set_window(self.default_window_size, self.default_max_packet_size)
chan._set_remote_channel(chanid, initial_window_size, max_packet_size)
finally:
self.lock.release()
m = Message()
m.add_byte(cMSG_CHANNEL_OPEN_SUCCESS)
m.add_int(chanid)
m.add_int(my_chanid)
m.add_int(self.default_window_size)
m.add_int(self.default_max_packet_size)
self._send_message(m)
self._log(DEBUG, 'Secsh channel %d (%s) opened.', my_chanid, kind)
if kind == 'auth-agent@openssh.com':
self._forward_agent_handler(chan)
elif kind == 'x11':
self._x11_handler(chan, (origin_addr, origin_port))
elif kind == 'forwarded-tcpip':
chan.origin_addr = (origin_addr, origin_port)
self._tcp_handler(chan, (origin_addr, origin_port), (server_addr, server_port))
else:
self._queue_incoming_channel(chan)
def _parse_debug(self, m):
always_display = m.get_boolean()
msg = m.get_string()
lang = m.get_string()
self._log(DEBUG, 'Debug msg: {0}'.format(util.safe_string(msg)))
def _get_subsystem_handler(self, name):
try:
self.lock.acquire()
if name not in self.subsystem_table:
return None, [], {}
return self.subsystem_table[name]
finally:
self.lock.release()
_handler_table = {
MSG_NEWKEYS: _parse_newkeys,
MSG_GLOBAL_REQUEST: _parse_global_request,
MSG_REQUEST_SUCCESS: _parse_request_success,
MSG_REQUEST_FAILURE: _parse_request_failure,
MSG_CHANNEL_OPEN_SUCCESS: _parse_channel_open_success,
MSG_CHANNEL_OPEN_FAILURE: _parse_channel_open_failure,
MSG_CHANNEL_OPEN: _parse_channel_open,
MSG_KEXINIT: _negotiate_keys,
}
_channel_handler_table = {
MSG_CHANNEL_SUCCESS: Channel._request_success,
MSG_CHANNEL_FAILURE: Channel._request_failed,
MSG_CHANNEL_DATA: Channel._feed,
MSG_CHANNEL_EXTENDED_DATA: Channel._feed_extended,
MSG_CHANNEL_WINDOW_ADJUST: Channel._window_adjust,
MSG_CHANNEL_REQUEST: Channel._handle_request,
MSG_CHANNEL_EOF: Channel._handle_eof,
MSG_CHANNEL_CLOSE: Channel._handle_close,
}
class SecurityOptions (object):
"""
Simple object containing the security preferences of an ssh transport.
These are tuples of acceptable ciphers, digests, key types, and key
exchange algorithms, listed in order of preference.
Changing the contents and/or order of these fields affects the underlying
`.Transport` (but only if you change them before starting the session).
If you try to add an algorithm that paramiko doesn't recognize,
``ValueError`` will be raised. If you try to assign something besides a
tuple to one of the fields, ``TypeError`` will be raised.
"""
#__slots__ = [ 'ciphers', 'digests', 'key_types', 'kex', 'compression', '_transport' ]
__slots__ = '_transport'
def __init__(self, transport):
self._transport = transport
def __repr__(self):
"""
Returns a string representation of this object, for debugging.
"""
return '<paramiko.SecurityOptions for %s>' % repr(self._transport)
def _set(self, name, orig, x):
if type(x) is list:
x = tuple(x)
if type(x) is not tuple:
raise TypeError('expected tuple or list')
possible = list(getattr(self._transport, orig).keys())
forbidden = [n for n in x if n not in possible]
if len(forbidden) > 0:
raise ValueError('unknown cipher')
setattr(self._transport, name, x)
@property
def ciphers(self):
"""Symmetric encryption ciphers"""
return self._transport._preferred_ciphers
@ciphers.setter
def ciphers(self, x):
self._set('_preferred_ciphers', '_cipher_info', x)
@property
def digests(self):
"""Digest (one-way hash) algorithms"""
return self._transport._preferred_macs
@digests.setter
def digests(self, x):
self._set('_preferred_macs', '_mac_info', x)
@property
def key_types(self):
"""Public-key algorithms"""
return self._transport._preferred_keys
@key_types.setter
def key_types(self, x):
self._set('_preferred_keys', '_key_info', x)
@property
def kex(self):
"""Key exchange algorithms"""
return self._transport._preferred_kex
@kex.setter
def kex(self, x):
self._set('_preferred_kex', '_kex_info', x)
@property
def compression(self):
"""Compression algorithms"""
return self._transport._preferred_compression
@compression.setter
def compression(self, x):
self._set('_preferred_compression', '_compression_info', x)
class ChannelMap (object):
def __init__(self):
# (id -> Channel)
self._map = weakref.WeakValueDictionary()
self._lock = threading.Lock()
def put(self, chanid, chan):
self._lock.acquire()
try:
self._map[chanid] = chan
finally:
self._lock.release()
def get(self, chanid):
self._lock.acquire()
try:
return self._map.get(chanid, None)
finally:
self._lock.release()
def delete(self, chanid):
self._lock.acquire()
try:
try:
del self._map[chanid]
except KeyError:
pass
finally:
self._lock.release()
def values(self):
self._lock.acquire()
try:
return list(self._map.values())
finally:
self._lock.release()
def __len__(self):
self._lock.acquire()
try:
return len(self._map)
finally:
self._lock.release()
|