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TCP
Unknown
110 POP3
POP3 lets mail clients download messages from remote mailboxes for local storage.
Security Context
Port 110 is context-dependent. Its risk depends on the daemon behind it, whether the traffic is encrypted, and how tightly the listener is scoped to trusted networks.
- !Use POP3S when credentials must not cross the network in plaintext.
Nmap Check
Use a version probe first so you confirm whether the expected service is really what is listening on this port.
nmap -sV -p 110 <host>Firewall Commands
UFW
sudo ufw allow 110/tcpiptables
sudo iptables -A INPUT -p tcp --dport 110 -j ACCEPT