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I am quite newbie to Linux administration. My ss command started to terminate with Segmentation fault and I don't know how to investigate the reason and solve the problem.

Details: While setting up machine on Amazon EC2 I came at some point to the situation, when ss started to terminate with Segmentation fault. I am not sure when exactly was the cause since I installed bunch of software meanwhile. Restarting the machine does not help.

I made these observations:

ss - exits with Segmentation fault

ss -4 - runs OK

ss -6- exits with Segmentation fault

There is no other message I could start with. What steps could I take to solve the problem? Thanks for your hints.

I am running Ubuntu Hardy Heron 8.04 LST.

Please, don't suggest alternatives to ss. I I don't run it myself, it's used by bijk-node, which is a server monitoring tool (see bijk.com). As a workaround I disabled this particular statistics, but I would like to have it back.

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Have you checked the output of the dmesg command or your /var/log/messages file for output related to the segmentation fault? –  rems Feb 11 '11 at 10:02

1 Answer 1

up vote 1 down vote accepted

I think your problem is due to IPV6 that has been turned off, this is quite a common issue, for example read this RedHat report.

If this is the issue you can either turn IPV6 on or submit a bug report to Ubuntu.

If it doesn't help, In general you need a debugger like gdb.

But gdb or any other debugging tool needs debugging symbols of each dependency of the command you need to troubleshoot.

As one link is better than 1000 words, to begin, I advice to read this IBM Developer Works article (a great article honestly).

Be aware that if IPV6 is the issue and you want to solve it yourself, you'll have to download the source code, fix and recompile it

UPDATE

I forgot to mention you can use strace as well to see where ss crash:

strace ss -6

At least you should see the system calls involved.

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Thanks, running strace was exactly the piece I missed. It confirms your diagnosis of disabled ipv6, the last record is: open("/proc/net/tcp6", O_RDONLY) = -1 ENOENT (No such file or directory) --- SIGSEGV (Segmentation fault) @ 0 (0) --- +++ killed by SIGSEGV +++ –  Michal Feb 11 '11 at 10:49
    
I'm pleased you succeeded :-) @Michal –  tmow Feb 11 '11 at 12:05

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