UDP Port 23 – Telnet (Legacy Remote Terminal)

About UDP Port 23

Port 23 carries the IANA assignment for telnet. The IANA description reads: ‘Telnet’. This port appears in 1 IDS rule and does not have notable malware activity indicators in our data.

IDS Rule References

1 IDS / security rule reference UDP port 23. Treat that number as context, not a danger score. Many detection rules are written against groups of ports rather than one service, web ports especially, so common web alternate ports inherit large counts while genuinely sensitive services can show few rules or none. Presence in IDS rules does not mean traffic on this port is malicious.

Rule categories (top 1): attempted-admin (1).

Sample rule descriptions for UDP port 23:

• SERVER-OTHER NETGEAR TelnetEnable attempt

Data Sources

This information is compiled from: IANA Service Name and Transport Protocol Port Number Registry, Emerging Threats Open Ruleset (BSD 2-Clause / GPLv2 per SID range), and Snort Community Rules (GPLv2).