Unix & Linux Stack Exchange is a question and answer site for users of Linux, FreeBSD and other Un*x-like operating systems. It's 100% free, no registration required.

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

I've got an LXC container, on the host I've got a bridge between the LXC container and eth0.

The LXC container can ping it's Host, but can't ping the gateway of The host is able to ping the gateway.

tcpdump on the interface created for the LXC container is sending the pings to the router and is getting a reply back. But a tcpdump within the container shows nothing. Furthermore, running tcpdump in the container hangs when you press ^C (20-40sec), that doesn't happen in the host.

Any ideas what I should look for here?

root@hadoop-jobtracker:~# ping &
[1] 876
root@hadoop-jobtracker:~# PING ( 56(84) bytes of data.

root@hadoop-jobtracker:~# tcpdump
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on eth0, link-type EN10MB (Ethernet), capture size 65535 bytes
::::20+ sec delay occurs here::::
05:56:34.835833 IP > Flags [P.], seq 2715418718:2715418910, ack 3505056160, win 196, options [nop,nop,TS val 1608155 ecr 1608151], length 192

1 packet captured
111 packets received by filter
80 packets dropped by kernel
share|improve this question
never run tcpdump w/o '-n' you might be eaten alive by dns-hickups ;) – Oluf Lorenzen Apr 2 '13 at 20:33
You enabled IPv4 forwarding with sysctl? – 0xC0000022L May 10 '15 at 21:17

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Browse other questions tagged or ask your own question.