This happened to a Plesk 8.x Linux (RH) server, the problem was that smtp service was up and running, and the queue was very light , but smtp wouldn’t accept any connections at port 25 even from localhost.
In the /var/log/messages I saw this disturbing message:
xinetd[#]: Deactivating service smtp due to excessive incoming connections. Restarting in 30 seconds.
If you see a lot of smtp connections or your server gets constantly in spam black lists, maybe you should check if some bot spams through your server.
The are 2 cases of spamming through a box:
1)using unsecure php forms that bots abuse
2)using smtp connection from an outside client
this artice is about the 2nd case,
I guess most of you did face situtation where you type top and see a lots of unknown or mysterious scripts/utils running that take over top screen and your machine resources.
most of the times these scripts (like the irc bots that I encountered) run via perl and disguise them selfs using names like : /usr/local/apache/bin/httpd -DSSL
ofcourse if you try to kill one another 100 run in the same time, so the best way is to
Lets say you have installed 2 OS in your pc Windows & Linux in separate partitions and you use GRUB as a boot loader, then if you some day decide to remove the linux partition (as I did) you will face an error uppon reboot , that will be GRUB Error 22, thats because grub is looking to find its files in the “erased” linux partition which ofcourse isnt there.
edit the file /root/.bashrc and add the following lines: (more…)
You automate ftp with the unix shell, all you need is a .netrc file which will contain the info for each server you want to connect to. (more…)