I am running CentOS 6. It is connected to OpenVPN with the following routes:

Destination Gateway Genmask Flags Metric Ref Use Iface UH 0 0 0 tun0 UH 0 0 0 tun0 U 0 0 0 eth0 U 1002 0 0 eth0 UG 0 0 0 eth0

When connected, my ifconfig shows the correct address for tun0:

inet addr:

After setting up the VPN, I restart sshd. When I try to ssh in to this system from a host on the VPN, the connection attempt times out. If I use tcpdump -i tun0 I get:

09:25:30.592685 IP > Flags [S], seq 2108197737, win 8192, options [mss 1366,nop,nop,sackOK], length 0

However, no response ever goes back across the tunnel. The response isn't being sent across eth0 either- I trapped eth0 and didn't have a packet trying to go back to

I know sshd is listening on all interfaces because netstat -l shows:

tcp 0 0 *:ssh : LISTEN

I even made sure my iptables allow incoming connections on the VPN port and the SSH port, although that shouldn't be an issue because the connections should be piggybacking on the current VPN session.

Any ideas? I'm at a loss, because as far as I can tell everything is set up properly.

1 Answer 1


The routes for tun0 are incorrect: the netmasks are (there is no ip matching such a route).

You probably need oder depending on how you configured your VPN.

  • did it. Stupid me. Thanks so much!
    – jssblck
    Feb 12, 2014 at 16:34

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