Port 110 · POP3

Port 110 is POP3, TCP.

Post Office Protocol v3 — email retrieval. Downloads messages and typically deletes them from the server.

Palo Alto

Create the service object for this port, then allow the App-ID on it. Restricting the rule to the port's service object keeps the rule working on a non-default port and stops the App-ID matching on other ports. Replace the placeholders with your own rule name and zones.

set service tcp-110 protocol tcp port 110

set rulebase security rules <rule-name> from <from-zone> to <to-zone> source any destination any application pop3 service tcp-110 action allow

Risk and exposure

Rated medium risk. Restrict this port to the sources that need it and keep the service patched; avoid exposing it to the whole internet unless the service is meant to be public.

Check it

• Linux ss -tlnp | grep :110
• PowerShell Test-NetConnection <host> -Port 110
• nmap nmap -p 110 <host>

Related ports

• 995 POP3S
• 25 SMTP
• 143 IMAP
• 465 SMTPS
• 587 SMTP Submission
• 993 IMAPS

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