Having Portmap instrusion problems

I have just installed my first Linux server. I am certainly a novice at Linux and need some help.

Shortly after installing RedHat 6.2 in its default server configuration, I am getting emails from people claiming that this machine is trying to break into their network. Most of them are saying that I am trying to break in on port 111 but serveral other ports have shown up as well.

I’m sure this is something simeple but I have not been able to find an answer anywhere.