Server Fault is a question and answer site for system and network administrators. 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

Having a issue very similar to linux routing bug? I have a ubuntu 12.04 system(kernel 3.10) with ifconfig as

eth0      Link encap:Ethernet  HWaddr 40:61:86:c9:a2:5f  
          inet addr:  Bcast:  Mask:
          inet6 addr: fe80::4261:86ff:fec9:a25f/64 Scope:Link
          RX packets:32861 errors:0 dropped:0 overruns:0 frame:0
          TX packets:900 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:2859333 (2.8 MB)  TX bytes:79814 (79.8 KB)

lo        Link encap:Local Loopback  
          inet addr:  Mask:
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:16436  Metric:1
          RX packets:221 errors:0 dropped:0 overruns:0 frame:0
          TX packets:221 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:20290 (20.2 KB)  TX bytes:20290 (20.2 KB)

and route -n as

Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface         UG    0      0        0 eth0     U     1000   0        0 eth0     U     1      0        0 eth0

I am able to reach IP address and all addresses in 172.16.1., but I am not able to reach any other addresses in 172.16.0. network except 36. I see that the ARP has resolved the ifaddress of that I am trying to access but ping or ssh are not going through. Tried adding host route directly with gateway as but still didn't work. What could be the problem?.

share|improve this question
Can you access that host from any other host? Also, do you have a firewall on that host? – Khaled Jan 9 '13 at 12:07
I cannot access in reverse direction either, and no firewall in between. BTW, Thanks for the edit. – Mani Jan 9 '13 at 12:12
The host is a Ubuntu 12.10 server that is able to reach other 172.16.0. addresses and none of the 172.168.1. addresses in reverse direction. – Mani Jan 9 '13 at 12:22

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.