| Protocol | Port | | :--: | ---- | | DHCP | UDP port 67 (servers)<br>UDP port 68 (clients) | | ARP | None | | Telnet | TCP port 23 | | SSH | TCP port 22 | | POP3 | TCP/UDP port 110 (unencrypted)<br>TCP/UDP port 995 (encrypted, SSL/TLS) | | IMAP | TCP port 143 (unencrypted)<br>TCP port 993 (encrypted, SSL/TLS) | | SMTP | TCP/UDP port 587 (encrypted, TLS) |