We have a Cisco Router 2811.
After doing a port scan, we found that ports 21, 23, 53, and 110 are open.
I can understand port 23 for remote telnet access but I'm confused about the rest.
I know for sure these ports are not open on our firewall. I have triple checked this.
Why is FTP (21), DNS (53) and POP3 (110 open by default? Can someone please explain? Any docs on how to close these would be helpful too.
Thanks in advance everyone.