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// Other services

Port 1951: bcs-lmserver

Port 1951 is assigned by IANA to bcs-lmserver (bcs-lmserver).

1951

How bcs-lmserver works

Other services
client:1951bcs-lmserverresponse client:1951bcs-lmserverresponse

The client sends a request to port 1951 and the bcs-lmserver 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 1951 dangerous?

We have no specific security note for port 1951. 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 1951

ServicePortTransportDescriptionReferenceUpdated
bcs-lmserver 1951 TCP, UDP bcs-lmserver - -

// source: IANA service name and port number registry

03 Check it

Which program uses port 1951, and is it reachable?

Linux

sudo ss -ltnup 'sport = :1951'      # process listening on 1951
sudo lsof -nP -i :1951

macOS

sudo lsof -nP -i :1951

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 1951 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 1951
netstat -ano | findstr :1951

From another machine

nmap -p 1951 -sV <host>
sudo nmap -sU -p 1951 <host>
nc -zv <host> 1951

Block it in the firewall

sudo ufw deny 1951/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 1951" -Direction Inbound -LocalPort 1951 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 1951 used for?

Port 1951 is assigned by IANA to bcs-lmserver (bcs-lmserver).

Is port 1951 TCP or UDP?

Port 1951 is registered for TCP and UDP.

Is it safe to open port 1951?

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 1951 is open?

On Linux run "ss -ltnup 'sport = :1951'", on macOS "lsof -nP -i :1951", and on Windows "netstat -ano | findstr :1951" to see the local process. From another machine, "nmap -p 1951 <host>" shows whether it is reachable.

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