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SESK: Stuff Everyone Should Know · sesk.info/secplus-tacacs-plus-tcp-49

TACACS+ is used for network device administration. Which transport and port does it use?

TCP port 49, assigned by IANA for TACACS+.

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  1. UDP port 1812
  2. UDP port 88
  3. TCP port 49 ✔

Why: TACACS+ runs over TCP, unlike RADIUS, which uses UDP. Port 49 is the one IANA allocated for it. It is often used to control who can log in to switches and routers.

Huh, didn't know that: RADIUS originally used UDP port 1645 but its officially assigned port is 1812.

The dad joke
TACACS+ insists on TCP. It wants proof every packet arrived before it lets anyone log in to the router.
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References

Answer: TCP port 49. TACACS+ runs over TCP, unlike RADIUS, which uses UDP. Port 49 is the one IANA allocated for it. It is often used to control who can log in to switches and routers.

  1. IETF RFC 8907, The TACACS+ Protocol www.rfc-editor.org/rfc/rfc8907
    TACACS+ uses TCP for its transport. TCP Server port 49 is allocated
    Checked 2026-10-10.
  2. IETF RFC 2865, Remote Authentication Dial In User Service (RADIUS) www.rfc-editor.org/rfc/rfc2865
    The officially assigned port number for RADIUS is 1812.
    Checked 2026-10-10.

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