Linux OS help

Hi,

I have Oracle 8.1.7 running on
Red Hat Linux release 7.0 (Guinness)
Kernel 2.2.16-22smp on an i686.

I need help with these 3 tasks:
Task 1. Change server name (IP address remains the same).
I am looking for info. on how to change server name.
Does server name change effect software on the server (example Oracle server
...etc) ?
If yes, what do I have to do to correct the problems.


For below mentioned services I was told "Port is open"
I want to know how to close ports.
Just in case If I close a wrong port or a required port I want to find the
ports and
open a closed port (if necessary).

 general/tcp
 ssh (22/tcp)
 telnet (23/tcp)
 smtp (25/tcp)
 finger (79/tcp)
 sunrpc (111/tcp)
 auth (113/tcp)
 login (513/tcp)
 shell (514/tcp)
 printer (515/tcp)
 submission (587/tcp)
 unknown (1521/tcp)
 unknown (1024/tcp)
 unknown (1025/udp)
 unknown (1024/udp)
 sunrpc (111/udp)
 ftp (21/tcp)

In short I am looking for command for to find out open and closed
ports(services)
Command to close a open port (service)
Command to open a closed port (service).

Task 3. Applying patches (security patches).
Where can I get OS patches ?
Where can I get instructions on how to apply patches ?

If I run into problems who will be able to help.
Don't tell me Linux Support .....!

Thanks
Reddy