proc setup
/proc/sys/net/ipv4/ip_forward
Set to 1 for IP forwarding (routing).
/proc/sys/net/ipv4/ip_dynaddr
Set to 1 for dynamic IPs.
Netfilter system calls
/proc/sys/net/ipv4/netfilter
Netfilter modules
/lib/modules/kernel_version/kernel/net/ipv4/netfilter/
The lowercase modules are for maches and the uppercase ones are for targets.
CONNTRACK
Conntrack table: /proc/net/ip_conntrack
Named hashlimit hashes: /proc/net/ipt_hashlimit/
Conntrack helper modules
ip_conntrack_ftp
ip_conntrack_irc
#probably a bad idea on production non-irc servers will all the kids planting irc bots where ever they can
ip_conntrack_tftp
#the helper module for trivial FTP – probably not needed
ip_conntrack_amanda
Note that if you also use NAT you need to also load the helper modules for NAT (they should be starting with ip_nat_):
ip_nat_ftp
ip_nat_irc