Network Port: 110
Network Port Reference Guide
Registered Service Name
POP3 (Mail Retrieval)
Transport Protocol
TCP
Functional Overview
Port 110 is utilized by Post Office Protocol version 3 (POP3) for downloading emails from a remote server mailbox.
Security Risks & Vulnerabilities
Transmits login credentials and message contents in plain text. Secure POP3 (POP3S) on encrypted Port 995 should be used instead.
How to audit network port status
1. Scan Open Ports: Use our Port Scanner utility to verify if this port is actively listening on your host.
2. Verify Encryption: Audit the service layer to confirm SSL/TLS is protecting transmission payload.
3. Hardening Rules: Apply the firewall instructions below to shut down unauthorized inbound ports.
UFW Firewall Rules
Allow Command
sudo ufw allow 110/tcp
Block Command
sudo ufw deny 110/tcp
iptables Firewall Rules
Allow Command
sudo iptables -A INPUT -p tcp --dport 110 -j ACCEPT
Block Command
sudo iptables -A INPUT -p tcp --dport 110 -j DROP