Today I was playing around with Nmap on Ubuntu Linux. I performed a port scan on our home router with
nmap -sV 192.168.1.1
The results were as follows:
**Starting Nmap 7.01 ( https://nmap.org ) at 2016-09-18 12:08 SAST Nmap scan report for homerouter.cpe (192.168.1.1) Host is up (0.0029s latency). Not shown: 992 closed ports PORT STATE SERVICE VERSION 22/tcp open tcpwrapped 23/tcp filtered telnet 53/tcp open domain 80/tcp open http Huawei E5172 router http admin 443/tcp open ssl/http Huawei E5172 router http admin 631/tcp filtered ipp 3000/tcp open ppp? 8081/tcp filtered blackice-icecap Service Info: Device: broadband router; CPE: cpe:/h:huawei:e5172
There were more ports open than I expected. For example, I can understand why port 80 and 22 were open by default. But why were ports 23, 53, 631, and 3000 open?
Should these be open? Are these ports a security risk to be left open, or are these ports needed for essential services? And if so, what are these essential services?