[Icecast] Re: Anyone seen this?

Chuck Tellechea chuckt at tellechea.org
Fri Apr 29 17:03:40 UTC 2005


lsof == List open files

If you have it installed it should be in: /usr/sbin/lsof
(At least that's where Debian puts it).

You would use it like this:

lsof -c icecast2

That would list every file (socket, pipe, regular file, etc.) open by 
every icecast2 process running. You could then grep for instances of 
values being present in particular fields in each record being 
returned, and count all instances of such values appearing in all 
records by using wc -l, etc.

For example, you could use something like the following:

root at aeicradio:~# lsof -c icecast2 | grep IPv4 | grep ESTABLISHED | wc 

Which would tell you that you have 36 currently established TCP 
connections to your server.

lsof is VERY usefull.

What Linux version are you running? If Debian, just do an: apt-get 
install lsof
If RedHat or a derivative, find the appropriate rpm and install it.

On Apr 29, 2005, at 12:04 AM, Geoff Shang wrote:

> Karl Heyes wrote:
>>> 1) file descriptor leak. If it's this, that's a pretty serious 
>>> icecast
>>> bug, probably exploitable as a DoS attack.
>> agreed, on linux check the /proc/<pid>/fd directory, use of utilities
>> like lsof may indicate excessive file descriptor usage.
> I don't appear to have lsof.  What does it do?
> What should I be seeing in this directory?   At time of writing, I see 
> 92 entries.
>>> 3) Hitting a kernel limit (either per-user or global). Unlikely 
>>> unless
>>> you have a lot of clients (hundreds or thousands). If it's a per-user
>>> limit, it should be easy to change. If it's global... well, you'd 
>>> need
>>> at least a few thousand clients for that, so it's unlikely.
>> check ulimit (-n) for open files, the default is 1024.
> Yeah it's 1024.
>>> All in all, I'd say the first one (fd leak) is the most likely, but
>>> there's not enough info here for me to guess at where (and if there
>>> was, I couldn't do anything about it anyway - don't have my computer
>>> with me here in Berlin :-).
>> agreed, the logs may indicate an unusual pattern showing up
> Well, let me know if you want them, I wouldn't know what to look for. 
> They're rather big. :)
> Geoff.
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"Living is easy with eyes closed;
         misunderstanding all you see...."
                 John Lennon

         Chuck Tellechea

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