Re: [SLUG] slowdown

From: ronan (ronan@tampabay.rr.com)
Date: Wed Feb 13 2008 - 18:56:29 EST


>> You could try "strace": strace xterm -r bash -c exit
>
> ("xterm -e")
>
> It pauses on this line:
>
> read(7, "\2\0\0\0\0\0\0\0\210\23\0\0\1\0\0\0\0\0\0\0\0\0\0\0/de"...,
> 1048) = 1048
>
> after the "read(7,". fd 7 is ... well, I don't see any open*() [1]
> giving a file descriptor that big. The largest I see before the pause
> are these:
I'm going out on a limb here, but could a tool like "lsof" show you
which file (if any) is attached to fd[7]? Or maybe by looking in the
/proc filesystem under that PID?
>
>
> open("/usr/lib/X11/locale/common/ximcp.so.2", O_RDONLY) = 5
> open("/usr/share/X11/locale/compose.dir", O_RDONLY) = 5
> open("/usr/share/X11/locale/iso8859-1/Compose", O_RDONLY) = 5
> open("/lib/terminfo/x/xterm", O_RDONLY|O_LARGEFILE) = 5
>
> Are there other operations which can give a file descriptor?
Other system calls that can allocate a file descriptor: socket, mmap,
pipe-something-or-other?

>
>> The rootkit is an interesting possibility.
>
> Pretty poor rootkit if it doesn't use the CPU and doesn't open
> connections:
>
> root@pc:~# netstat -A inet -ap | grep -v WAIT
> Active Internet connections (servers and established)
> Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name
> tcp 0 0 *:xtelw *:* LISTEN 5129/festival
...
Don't forget that much of the point to a rootkit is that the tools that
you would use to diagnose your system have been altered to help hide to
rootkit. There might be processes and connections that your tools aren't
showing you.

--ronan

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