Network Port: 993
Network Port Reference Guide
Registered Service Name
IMAP over SSL (IMAPS)
Transport Protocol
TCP
Functional Overview
Port 993 is the secure, TLS-encrypted port for Internet Message Access Protocol (IMAP) operations.
Security Risks & Vulnerabilities
Relatively secure. Ensure the mail server enforces strong cipher suites and trust certificates are valid.
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 993/tcp
Block Command
sudo ufw deny 993/tcp
iptables Firewall Rules
Allow Command
sudo iptables -A INPUT -p tcp --dport 993 -j ACCEPT
Block Command
sudo iptables -A INPUT -p tcp --dport 993 -j DROP