/etc/arno-iptables-firewall/plugins/ is in arno-iptables-firewall 2.0.1.c-1.
This file is owned by root:root, with mode 0o755.
..
/etc/arno-iptables-firewall/plugins/dmz-dnat.conf
/etc/arno-iptables-firewall/plugins/dsl-ppp-modem.conf
/etc/arno-iptables-firewall/plugins/dyndns-host-open.conf
/etc/arno-iptables-firewall/plugins/ids-protection.conf
/etc/arno-iptables-firewall/plugins/ipsec-vpn.conf
/etc/arno-iptables-firewall/plugins/ipv6-over-ipv4.conf
/etc/arno-iptables-firewall/plugins/linux-upnp-igd.conf
/etc/arno-iptables-firewall/plugins/mac-address-filter.conf
/etc/arno-iptables-firewall/plugins/multiroute.conf
/etc/arno-iptables-firewall/plugins/pptp-vpn.conf
/etc/arno-iptables-firewall/plugins/rpc.conf
/etc/arno-iptables-firewall/plugins/sip-voip.conf
/etc/arno-iptables-firewall/plugins/ssh-brute-force-protection.conf
/etc/arno-iptables-firewall/plugins/traffic-accounting.conf
/etc/arno-iptables-firewall/plugins/traffic-shaper.conf
/etc/arno-iptables-firewall/plugins/transparent-dnat.conf
/etc/arno-iptables-firewall/plugins/transparent-proxy.conf