Tue Mar 22 17:39:34 EET 2011

Fixing error: "net.ipv4.netfilter.ip_conntrack_tcp_timeout_syn_recv" is an unknown key on Debian Linux

If you're trying to tune up your:

net.ipv4.netfilter.ip_conntrack_tcp_timeout_syn_recv = 30 net.ipv4.netfilter.ip_conntrack_tcp_timeout_time_wait = 30 net.ipv4.netfilter.ip_conntrack_tcp_timeout_fin_wait = 30 net.ipv4.netfilter.ip_conntrack_max = 1048576

in /etc/sysctl.conf and you come across the error messages;

"net.ipv4.netfilter.ip_conntrack_tcp_timeout_syn_recv" is an unknown key
"net.ipv4.netfilter.ip_conntrack_tcp_timeout_time_wait" is an unknown key
"net.ipv4.netfilter.ip_conntrack_tcp_timeout_fin_wait" is an unknown key
"net.ipv4.netfilter.ip_conntrack_max" is an unknown key


whether you're executing:

debian:~# sysctl -p


in order to make the net.ipv4.netfilter.* values to be set as a kernel values to iptables, you need to modify your /etc/modules file and add the nf_conntrack_ftp in it, here is how:

echo 'nf_conntrack_ftp' >> /etc/modules


Now to make the new settings be reloaded issue the command:

debian:~# sysctl -p


Now the values will be properly set and you will see no longer the is an unknown key error messages like so:

net.ipv4.netfilter.ip_conntrack_tcp_timeout_syn_recv = 30
net.ipv4.netfilter.ip_conntrack_tcp_timeout_time_wait = 30
net.ipv4.netfilter.ip_conntrack_tcp_timeout_fin_wait = 30
net.ipv4.netfilter.ip_conntrack_max = 1048576