Hi. I'm really new to linux (I made my first installation about 2 weeks ago) but thanks to all great docs online, everything has gone well.
I'm going to use the machine as a server (it's not being used as a server yet) and I want it as secure as possible. Yes, I will buy a hardware firewall in the near future, and I also plan to install IPfilter or IPchain or whatever the firewall is called. However I want to disable unnecessary services aswell. I installed ssh and tcp wrappers (i hope they are working properly :)) and disabled all services in inetd.conf. But there are still several services running.
I did a portscan on my machine and found the following ports open:
22,25,80,81,82,83,110,111,119,389,587,898
I'm not familiar with all of them 22 is ssh, and that one should be open, but 25 (and 587 aswell?) for example is sendmail, which I do not want to have open, and I havn't found out any way of disableing it..
The ports 80-83 may be some http-thing, you tell me :)
Should they be running or not? And how to disable them.
Any other tip on how to make the machine more secure is welcome, but 1st of all, answer how to close the sendmail thingie..

Thanks in advance /Ingmar

Sendmail is a service started at boot time through the rc mechanism. Have a look at the /etc/rc*.d directories for startup scripts.

mv /etc/rc2.d/S88sendmail /etc/rc2.d/s88sendmail

Only scripts that start with an upper case S are started at boot time.

Have a look at the file /etc/services for a list of common services and the port numbers.