port issues

[XTCHost]

I have a computer using F8 that I manage, having just checked the security log files I see atempts are being made ona daily basis to hack in using ssh on port 22

I have jus done a nmap scan and have also found the below

Discovered open port 53/tcp - does this ned to be open

20/tcp closed ftp-data
21/tcp closed ftp
22/tcp open ssh OpenSSH 4.7 (protocol 2.0)
23/tcp closed telnet
53/tcp open domain?
80/tcp open http?

TCP Sequence Prediction: Difficulty=199 (Good luck!) - is this good?

I have root access to the computer, can someone advise on how I edit the firewall by cli please.

[markkuk]

From where did you run that nmap scan? Running nmap on the loopback interface is useless, you must run nmap on a different machine that's outside your firewall.

[leigh123linux]

Originally Posted by XTCHost

I have a computer using F8 that I manage, having just checked the security log files I see atempts are being made ona daily basis to hack in using ssh on port 22

I have jus done a nmap scan and have also found the below

Discovered open port 53/tcp - does this ned to be open

20/tcp closed ftp-data
21/tcp closed ftp
22/tcp open ssh OpenSSH 4.7 (protocol 2.0)
23/tcp closed telnet
53/tcp open domain?
80/tcp open http?

TCP Sequence Prediction: Difficulty=199 (Good luck!) - is this good?

I have root access to the computer, can someone advise on how I edit the firewall by cli please.

TCP/UDP Port 53 is used for DNS Service !

P.S why don't you change the SSH port from 22 to 15000+ ? , this would stop most attacks as script-kiddies normally only scan up to port 1000

[XTCHost]

I did run the nmap from another system as I am on a two week "holiday" spending all my time trying to learn a little more about Fedora/linux

I can access the comp via ssh and will change the port when I get home. It is a friends computer that I set up behind a Belkin router that for some reason I cannot access. I may not have set it to allow remote access. I am using F9 and will upgrade him.

As I cannot use a gui I would like to close the open ports via cli if possible