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Re: Commands failing silently?

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Dan Bongert Re: [CentOS] Commands failing silently?
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mouss wrote:
> Dan Bongert wrote:
>> Hello all:
>>
>> I have a couple CentOS 4 servers (all up-to-date) that are having
>> strange command failures. I first noticed this with a perl script that
>> uses lots of system calls.
>>
>> thoth(66) /tmp> uname -a
>> Linux thoth.ssc.wisc.edu 2.6.9-67.0.7.ELsmp #1 SMP Sat Mar 15 06:54:55
>> EDT 2008 i686 i686 i386 GNU/Linux
>>
>> Nothing in either dmesg or /var/log/messages seems to indicate any
>> problems. It also doesn't seem to matter what the command is -- ls is
>> the quickest test, but sshd will sometimes to fail to spawn children,
>> etc. There aren't a large amount of processes on the machine either --
>> only 122 at the moment.
>>
>> Has anyone seen this behavior before? Have I been hit with some sort
>> of cunning rootkit? This machine shouldn't be publicly accessible;
>> it's behind our firewall.
>
> where is /tmp mounted? is this an external disk (usb, ...)? is it an nfs
> mount?

It's a local disk:

thoth(97) /tmp> df -h .
Filesystem            Size  Used Avail Use% Mounted on
/dev/md4               16G   77M   15G   1% /tmp

Though 'ls' was just an example -- just about any program will fail. The 'w'
command will fail too:

thoth(118) /tmp> w
   16:06:51 up  5:34,  1 user,  load average: 0.94, 1.46, 2.04
USER     TTY      FROM              LOGIN@   IDLE   JCPU   PCPU WHAT
dbongert pts/0    copland.ssc.wisc 14:16    0.00s  0.22s  0.05s w

thoth(119) /tmp> w
   16:06:52 up  5:34,  1 user,  load average: 0.94, 1.46, 2.04
USER     TTY      FROM              LOGIN@   IDLE   JCPU   PCPU WHAT
dbongert pts/0    copland.ssc.wisc 14:16    0.00s  0.22s  0.05s w

thoth(120) /tmp> w

thoth(121) /tmp> w

--
Dan Bongert                     [email protected: dbo...@wisc.edu]

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Thread : Commands failing silently?
1)
Dan Bongert Hello all: I have a couple CentOS 4 servers (all up-to-date) that are having strange command...
2)
Bill Campbell There is a very good chance that the machine has been cracked, and the system's /bin/ls routine...
3)
Dan Bongert Everything seems OK there: thoth(96) /tmp> sudo rpm -V coreutils procps util-linux Funnily enough,...
4)
Peter l Jakobi That's funny. Or due to the output of strace changing timing & stress. Try redirecting the strace...
5)
mouss where is /tmp mounted? is this an external disk (usb, ...)? is it an nfs mount?
6)
Dan Bongert It's a local disk: thoth(97) /tmp> df -h . Filesystem Size Used Avail Use% Mounted on /dev/md4 16G...
7)
William L. Maltby Hmmm... Sure it's failing? Maybe just the output is going somewhere else? After the command runs,...
8)
Dan Bongert Ok, it's definitely getting an error from somewhere: thoth(3) /tmp> ls thoth(4) /tmp> echo $?...
9)
William L. Maltby "~>" ? Got me on that one. Ditto. Although I should mention that unless you "man bash" and find the...
10)
Filipe Brandenburger Hi, 141 is SIGPIPE. If the process is killed by a signal, the return code will be 128+signal...
11)
mouss maybe check your PATH. try $ /bin/ls ...
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