[SOLVED] How can I close unnecessaries ports ?

[naruponk]

Hi,

I have just working with linux (CentOS 5.2)
I have seen around ten of ports are unwanted ports and need to be closed.
How can I close those port via command line ?

[RobinVossen]

with IPTABLES.
IPTABLES is a Firewall that is nested in your kernel. ITs CLI but there are a tremendous amount of GUIs for it.

Have fun =)

[naruponk]

Do you have any link to good resource about iptables ?

[HROAdmin26]

If ports are "open" it's because there is a process "listening" on that port. You close ports by disabling the processes you don't want running.

You can Google for netstat:

netstat -anp | more
Active Internet connections (servers and established)
Proto Recv-Q Send-Q Local Address           Foreign Address         State       PID/Program name   
tcp        0      0 0.0.0.0:902             0.0.0.0:*               LISTEN      3539/xinetd         
tcp        0      0 0.0.0.0:64423           0.0.0.0:*               LISTEN      22184/skype         
tcp        0      0 0.0.0.0:8333            0.0.0.0:*               LISTEN      3692/httpd.vmware   
tcp        0      0 0.0.0.0:53742           0.0.0.0:*               LISTEN      4583/rpc.statd      
tcp        0      0 0.0.0.0:111             0.0.0.0:*               LISTEN      2830/rpcbind        
tcp        0      0 0.0.0.0:22              0.0.0.0:*               LISTEN      3637/sshd           
tcp        0      0 127.0.0.1:631           0.0.0.0:*               LISTEN      3423/cupsd

Example:

tcp        0      0 0.0.0.0:902             0.0.0.0:*               LISTEN      3539/xinetd

Port 902 is open - listening on all interfaces (not any certain IP). PID 3593 has it open, which is xinetd.

[naruponk]

Thanks a lot ! , good example