Port 19 · Chargen

Port 19 is Chargen, TCP and UDP.

Character Generator — generates continuous character streams. No legitimate modern use; used in DDoS amplification attacks via UDP.

Palo Alto

Create the service objects 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-19 protocol tcp port 19
set service udp-19 protocol udp port 19

set rulebase security rules <rule-name> from <from-zone> to <to-zone> source any destination any application chargen service [ tcp-19 udp-19 ] action allow

Risk and exposure

Rated high risk. Services on this port are commonly targeted by attackers. Keep it off the internet, or put it behind a VPN or a strict source allow-list, and monitor access.

Check it

• Linux ss -tlnp | grep :19
• Linux ss -ulnp | grep :19
• PowerShell Test-NetConnection <host> -Port 19
• nmap nmap -p 19 <host>
• nmap nmap -sU -p 19 <host>

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