whatportis.com

Port 16452 services

2 entries are registered on port 1645. It is a registered port (1024–49151) — IANA records an assignee, but nothing stops other software from listening here, which is why the number carries more than one entry.

entries
2

services registered on this number

transport
tcp · udp

2 transports in use

in transit
0/2

entries encrypted on the wire

worst risk
4/10

1 of 2 iana-registered

Services on this port

ranked by lookups
portservicerisk
:1645RADIUS Authentication (Cisco/Juniper)caution
:1645SightLinesafe

01RADIUS Authentication (Cisco/Juniper)tcp · udp · unofficial · risk 4/10

Port 1645 was traditionally used for RADIUS authentication messages by vendors like Cisco and Juniper. As a protocol, RADIUS (Remote Authentication Dial In User Service) facilitates centralized Authentication, Authorization, and Accounting (AAA) for accessing network resources, widely adopted in network access servers, wireless controllers, VPNs, and more. Despite newer official port allocations, port 1645 remains in use in certain legacy or vendor-specific deployments.

port 1645 as RADIUS Authentication (Cisco/Juniper) →
filed underSecurityNetwork Services

Which one is on your host

ask the machine, not the registry

The registry says what 1645 is registered to. What is listening on it right now is decided by the host, and only the host can be asked. Each of these prints the process behind the socket.

linux
ss -ltnp | grep ':1645\b'
macos
lsof -nP -iTCP:1645 -sTCP:LISTEN
windows
netstat -ano | findstr :1645

On Linux and Windows the process name comes back with the socket; on macOS lsof needs sudo to name a process that isn't yours. Match what it prints against the 2 entries above.

A port number is not a service. Anything may listen on 1645 — what you actually met is decided by the host, not the registry. If a service is missing here, it belongs in the registry.

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