Network Port: 143
Network Port Reference Guide
Registered Service Name
IMAP (Internet Message Access)
Transport Protocol
TCP
Functional Overview
Port 143 is used by IMAP to retrieve and manage emails directly on mail servers without local downloading.
Security Risks & Vulnerabilities
Credentials and email contents are sent unencrypted. Encrypted IMAPS on Port 993 is the modern secure standard.
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 143/tcp
Block Command
sudo ufw deny 143/tcp
iptables Firewall Rules
Allow Command
sudo iptables -A INPUT -p tcp --dport 143 -j ACCEPT
Block Command
sudo iptables -A INPUT -p tcp --dport 143 -j DROP