I am writing a utility which will use Conntrack commands to show the connection states. I am a beginner and I wanted to play with the Conntrack before I could start my work. So, when I tried conntrack -L conntrack, I get the output which says there are no flows. But, I do have a telnet and one ssh connection to the machine, which is seen in netstat as in ESTABLISHED state.

I also did tail -f /proc/net/ip_conntrack but didn't see any output.

Am I missing something?


If /proc/net/ip_conntrack is empty, you may have conntrack modules not loaded. Try

modprobe nf_conntrack
  • I did lsmod | grep nf_conntrack. It shows that conntrack is loaded already. Do I need to configure firewall or something for this to work? As per my understanding, it is not needed for basic testing. – Gaurav Sinha Oct 19 '11 at 23:29
  • I dont know how but it started to work, thanks!! – Gaurav Sinha Oct 19 '11 at 23:52

You'll have to modprobe nf_conntrack and it's ipv4/ipv6 modules.

  • modprobe nf_conntrack
  • modprobe nf_conntrack_ipv4
  • modprobe nf_conntrack_ipv6

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