Portscanning fun!!!

[JaybOt]

hi all,

Situation:
I was doing a portscan on one of my servers (from the local net) in a bid to tighten the security, anyway, after stopping unwanted deamons i thought i would be cool to use different port numbers, other than the default, since there are so many to choose from... so, my question is simple.

Question:
How can i...
1. make a program lile smtpd (on ther server) accept connection ONLY on, lets say port 999

2. open / close a port for use. e.g. when i portscan, the port is or is not available.

I am using FreeBSD 4.2, i have looked at, and edited the /etc/services and /etc/protocols accordingly but installing a new service or protocol does not seem to open the ports i want to use. e.g. port scan does not list the port as open.

Thanks a bunch!

JayBot "Always know what you say, but don't always say what you know!"

 

[MikeLacey]

Hi Jay,

I don't know how you'd configure sendmail to listen on a different port - I would look in /etc/services to start with, I guess - but if you did you would not be able to accept mail from other systems, since they would be trying to connect to the old, well known, port.

As far as I'm aware you open a port with an entry in /etc/services that defines a program "listening" on that port. When you restart inetd, or send it a HUP signal, inetd will listen for you on that port and then wake up the appropriate program for you. Mike
michael.j.lacey@ntlworld.com
Email welcome if you're in a hurry or something -- but post in tek-tips as well please, and I will post my reply here as well.