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Re: Commands failing silently?

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Bill Campbell Re: [CentOS] Commands failing silently?
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On Mon, Mar 24, 2008, 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.
>
>Basically, sometimes a command just won't run:
>
>thoth(52) /tmp> ls
>
...
>
>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.

There is a very good chance that the machine has been cracked,
and the system's /bin/ls routine replaced by one hacked to hide
the cracker's programs.  ``rpm -V coreutils procps util-linux''
may well show several critical programs changed.

You can also try running ``strace /bin/ls'' to see what is going on.

Bill
--
INTERNET: [email protected: b...@celestial.com] Bill Campbell; Celestial Software LLC
URL: http://www.celestial.com/ PO Box 820; 6641 E. Mercer Way
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    -- H.L. Mencken, Minority Report
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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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