UDP 49
Synopsis
- UDP port 49 is used by the original TACACS and Cisco’s Extended TACACS (XTACACS) for network device AAA.
- Cisco IOS routers and switches (and early Cisco AS5xxx access servers) were commonly configured to authenticate via TACACS/XTACACS over UDP 49.
- Real server software that used UDP 49 includes Cisco’s xtacacsd (XTACACS daemon) on Unix and Livingston’s TACACS daemon used with Livingston PortMaster access servers.
- Many dial‑up/remote access NAS deployments in the 1990s used UDP 49 between the NAS (e.g., Livingston PortMaster) and their TACACS/XTACACS backends.
- While modern TACACS+ uses TCP 49, some environments keep legacy TACACS/XTACACS listeners on UDP 49 for backward compatibility with older gear.
- Security note: legacy TACACS over UDP is unencrypted and has been targeted for credential sniffing and brute‑force attempts when exposed to the internet.
Observed activity
Last 30 days
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