NMAP doesn't scan all ports
robina80 last edited by
i have installed nmap on my pfsense machine and i am running nmap on an IP (my pc) and i have got filezilla open (ftp client) and i am connected to my works ftp server and for some reason when i run a scan on my IP (while i have still kept the ftp connection active) it doesn't list port 21 as open ie being open or active, i find that a bit strange as i thought it would list any port open or active
it lists other ports being open/active but not port 21?
Unless your PC is actually listening for a connection from anywhere on port 21, then nmap won't see that as "open".
To nmap, "open" means that a service is waiting for inbound connections and accepts them (listening on a port), such as a web server or FTP server on the IP being scanned. If your client has a connection "open" to a remote server, that isn't something nmap can see as it's a fundamentally different concept.