/etc/services

[ramandegan]

Everybody says " close unused services on your computer".
I can see the services at /etc/services
I know how to disable them . But how can I get more information about that services ? I cant decide to close the service or not ? because I dont know what does it do ?
can anybody show me the way ?

[Cass]

What are the services you are confused about ??

normal services to be stopped can include anything from sendmail to telnet, there are many, your requirements will dictate which services to close and what to leave open.


Cass

[UziMonkey]

/etc/services holds a list of services and the port they most commonly run on. All these services are _not_ running on your machine, /etc/services exists only to give a service name to port number match, mostly for convenience.

To disable services, you have to know what you're really running. To do this, look in your init scripts. Since you didn't say which OS you're running, it's hard to give specific advice, but the startup scripts are usually in /etc/init.d. Links are made to these scripts in rcX.d, where X is the runlevel. If your system doesn't use this style of init scritps, there's probably a configuration file to shut services off, usually called /etc/rc.conf. Also, look at /etc/inetd.conf, services run through inetd are configured here.

[ramandegan]

oh. right. I use RH9 linux.
I mean when I read the etc/services I see many words that I ve never heard before. how can I know what they are ?

for example I see this line

echo 7/tcp
echo 7/udp
discard 9/tcp sink null
discard 9/udp sink null
systat 11/tcp users
daytime 13/tcp
daytime 13/udp
netstat 15/tcp
chargen 19/tcp ttytst source
chargen 19/udp ttytst source
ftp-data 20/tcp
ftp 21/tcp
telnet 23/tcp
smtp 25/tcp

In this example , ftp, smtp,telnet ok. but what are discard,chargen,systat,echo ...?

Actually I mean where can I find information about these services ? should I use man pages ?

[ryansutton]

Here ya go, hope this helps

http://www.iss.net/security_center/advice/Exploits/Ports/default.htm

[ramandegan]

thank you ever so much.
I read some of themm .