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// Other services

Port 3161: DOC1 License Manager

Port 3161 is assigned by IANA to doc1lm (DOC1 License Manager).

3161

How doc1lm works

Other services
client:3161doc1lmresponse client:3161doc1lmresponse

The client sends a request to port 3161 and the doc1lm service answers.

Transport
TCP · UDP
Exposure risk
not rated depends on the program listening
Encryption
Unknownnot stated by the registry
IANA status
Assigned1 registered service
Range
Registered (1024-49151)
Category
Other services
01 Security

Is port 3161 dangerous?

We have no specific security note for port 3161. Its risk depends on the program actually listening on it. General advice for other services services:

  • Close the port if nothing on the host needs it.
  • Identify the process that listens on it (commands below) before opening it in a firewall.
  • Expose a service only to the networks that use it.
02 Registry

IANA registry entries for port 3161

ServicePortTransportDescriptionReferenceUpdated
doc1lm 3161 TCP, UDP DOC1 License Manager - -

// source: IANA service name and port number registry

03 Check it

Which program uses port 3161, and is it reachable?

Linux

sudo ss -ltnup 'sport = :3161'      # process listening on 3161
sudo lsof -nP -i :3161

macOS

sudo lsof -nP -i :3161

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 3161 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 3161
netstat -ano | findstr :3161

From another machine

nmap -p 3161 -sV <host>
sudo nmap -sU -p 3161 <host>
nc -zv <host> 3161

Block it in the firewall

sudo ufw deny 3161/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 3161" -Direction Inbound -LocalPort 3161 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 3161 used for?

Port 3161 is assigned by IANA to doc1lm (DOC1 License Manager).

Is port 3161 TCP or UDP?

Port 3161 is registered for TCP and UDP.

Is it safe to open port 3161?

It depends on the program that listens on it. Open it only for a service you know and only to the networks that need it. Close the port if nothing on the host needs it.

How do I check if port 3161 is open?

On Linux run "ss -ltnup 'sport = :3161'", on macOS "lsof -nP -i :3161", and on Windows "netstat -ano | findstr :3161" to see the local process. From another machine, "nmap -p 3161 <host>" shows whether it is reachable.

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