NMAP reveals OpenPort on pfSense

[Eric]

Hello All and hope everyone is having a great holiday.

I ran NMAP to my pfSense external IP address by tethering my PC to my phone (i.e. completely different network). The result revealed that pfSense had port 21 open as below:

PORT STATE SERVICE VERSION
21/tcp open ftp?

As I don’t run FTP service in pfSense, I am confused why this port is open and not sure if it expose anything on my network. Please see the running services as picture below:

Does anyone has similar issue?

I then connected the PC to internal network and ran NMAP to pfSense gateway. This showed port 53 is open as below:

PORT STATE SERVICE
53/tcp open domain

I guess this is okay since I do have DNS service in pfSense. Would anyone agree?

Cheers,
Eric

[pavlos]

Can you check your external ip with www.grc.com (ShieldsUp) ?

I assume your config is ISP -> cable modem -> pfSense -> LAN

[Eric]

Thanks Pavlos. Yes you are correct on my network topology.

I have done an all port scan service and returned all ports closed.

Now I am wondering why NMAP would show port 21 is open …

Cheers,
Eric

[Eric]

Specifically, port 21 is shown as closed by ShieldsUp!