Opening, blocking and changing ports on RedHat

[Nitin Sharma]

/etc/services - is used to map ports and service-names to protocols, such as
-  telnet 23/tcp

The name "telnet" is then referenced on /etc/inetd.conf which would then map
these "service-names" to corresponding server that would get spawned(binary
executable). If you are on a centos, check for xinetd.

I havent tried this, but may be you could try this, make the service names
different on /etc/services - e.g. ssh_test 22/tcp , and run ssh using
inetd/xinetd. You might be getting warnings or errors starting the service
since it would reference a name "ssh" as the service name which wouldnot
have any port/protocol associated on /etc/services?


On Tue, Jan 4, 2011 at 12:52 PM, keith smith <klsmith2020 at yahoo.com> wrote:

>
>
> Hi,
>
> I'm working on several CentOS and one RHEL servers.  I needed to open a
> port the other day so I did a search and the info I found lead me to believe
> the only way to open or close a port was via iptables.  Is that the complete
> story?
>
> For example, if I want to open port 3306 for MySql I need two things?  1)
> The port needs to be listed in /etc/services (RedHat) and 2) the port needs
> to be opened via iptables.
>
> If I use a non-standard port (3306) I must add a line to the /etc/my.conf
> that defines the port such as "port=xxxx".
>
> Here is a twist.  I set my SSHD to port 2200 but did not change
> /etc/services, which lists ici on port 2200 for both tcp and udp.  I am able
> to shell in using port 2200.  Why no conflict?
>
> Thank you for your insight.
>
>
>
> ------------------------
> Keith Smith
>
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