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Port49— TACACS+

TCPSystem

TCP 49 is the registered port for TACACS+ (Terminal Access Controller Access-Control System Plus), the AAA protocol network devices use for centralized authentication, authorization and accounting of admin logins — think Cisco ISE or the open TACACS+ daemon.

Registry assignments, software defaults and local listeners are different things. A port number alone does not identify or secure a service.

Configuration and troubleshooting

For TACACS+ auth failures: verify the server address and shared key match exactly on the device (one character off fails silently), check the tac_plus log or ISE live sessions on the server side, and allow TCP 49 outbound from the device. TACACS+ obfuscates its payload body (unlike RADIUS, which only protects the password), but this does not meet modern encryption standards — run it over a trusted management network and rotate keys regularly.

Important limitations

TACACS+ payload obfuscation does not provide reliable confidentiality or replay protection (RFC 8907 §10 explicitly notes this limitation). Multi-vendor environments should also evaluate RADIUS (1812/1813) or modern alternatives. A weak shared key undermines the whole system — rotate it and never reuse SNMP community strings.

Read-only checks: run on the server host

Choose the commands for your OS. Check TCP and UDP separately. No result is not a lasting availability guarantee; inspect host and container separately.

Linux

sudo ss -ltnp 'sport = :49'

macOS

sudo lsof -nP -iTCP:49 -sTCP:LISTEN

Windows PowerShell

Get-NetTCPConnection -LocalPort 49 -State Listen

Sources and review

Sources checked on:

This review covers the explanations and sources on this page, not your device or every community software entry below.

Software Using This Port (2 software)

Community software entries: links are references, not individual verification.

TACACS Terminal Access Control

TerminalControlControlSystem

Authentication Systems

authenticationsystem

Usage Suggestions

  • Before using port 49, please confirm it is not occupied by other services
  • If you encounter port conflicts, consider using other ports or stopping the occupying service

Frequently asked questions

What is port 49 used for?

Port 49 sits in the System category. This page lists the registered purpose and the software commonly associated with it; to see what is actually listening on a specific machine, check the process with ss/netstat.

Is port 49 TCP or UDP?

The registered protocol on this page is TCP. The same number behaves independently on each protocol: TCP may be listening while UDP is idle, so check them separately.

How do I check if port 49 is in use?

On Linux: sudo ss -tlnp 'sport = :49' for an exact port match. On macOS: sudo lsof -nP -iTCP:49 -sTCP:LISTEN. On Windows PowerShell: Get-NetTCPConnection -LocalPort 49 -State Listen. A listener counts as confirmed only when you can see the bind address and process name; without root/admin you will not see other users' processes.

Is port 49 secure? Should I open it in my firewall?

A port number has no inherent security — it depends on whether the listening service is correctly configured and whether it needs exposure at all. Keep loopback/internal-only services firewalled; where public access is required, pair it with source restrictions, VPN or authentication. The caution section on this page lists port-specific risks.

Quick Info

Port
49
Protocol
TCP
Categories
System
Usage Status
2 software in use

Related Ports

Port 22TCP
Port 1812UDP
Port 1813UDP

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