wu-ftpd

[Mike Hassell]

Hello All,

I have an issue today with a server that has a lot of ftpd connections (200+) and we're seeing all kinds of delay today. Users connect to this server via VPN access (Nortel switch) and then ftp small files to the server. This morning we are seeing problems with wuftpd handling the amount of concurrent connections. Our error message is as follows:

ftpd[167340]: sleeping: fcntl lock of pid file failed: Permission denied

When researching this, I see that this error is somewhat common, but I'm also seeing a large amount of ftpd servers running, while only half of those are actually authenicated at the time. For instance:

ps -ef | grep ftpd | wc -l shows:

367

While the output from ftpwho shows:

218

Is this a file contention issue that wuftpd can't add it's PID to the main file, or does this relate more to network issues? Your thoughts?

Any help is greatly apperciated, thanks.

-Mike

[Christopher Caldwell]

I didn't get any hits on permission denied, but I did see similar issues ...

From Gregory A Lundberg of the WU-FTPD Development Group (www.wu-ftpd.org):


> Aug 2 10:04:57 media ftpd[7587]: sleeping: fcntl lock of pid file failed:
> Resource temporarily unavailable


This is normal and not a problem if you see it very infrequently. If your
server is operating normally, you can recompile to suppress these messages.
Personally, I'd ignore them so I could see if a more severe problem cropped
up.


> it always repeats this messages since yesterday.And no one can ftp on it
> this morning,the screen doesn't express anything .This ftp server can not
> work anymore. i have to restart it,but they appear again.who can tell me
> why this happen?how can i do with it ?


If it's caused by real traffic, it sounds like someone using your server
has a severly broken client (or firewall) .. or you're under a DoS attack
(I'd vote for a broken firewall as more likely, but a DoS is a distinct
possibility). In either case, sniff the traffic and firewall the culprit
away from your FTP server.


Another possibility is a bug in the OS. If the problem goes away after a
reboot, then look to see if there are any vendor patches you're not
installed, specifically those related to file systems and file locking.

All the message is says in the daemon needed to up date the PID files and
another copy of the daemon had them locked. So it's sleeping for a moment.
If you see this and your machine is not running a lot of FTP daemons,
somethign may be wrong.

[Ron Kinner]

You might want to look at
netstat -a |grep ftp
and see if you have a lot of connections stuck in FIN_WAIT.

This is caused by a stupid client which is not hanging up the circuit correctly. Your clients would not happen to be running on WinNT would they? There is a bug in WinNT which causes this if the circuit is noisy. There is a patch but you have to beg Microsoft help for it since it has not been released.

You can reduce the amount of time you wait in FIN_WAIT on an 11.0 or better with the right patch using NDD. That can help.

Also you can increase the number of FTP connections allowed.

Ron