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// Other services

Port 701: Link Management Protocol (LMP)

Port 701 is assigned by IANA to lmp (Link Management Protocol (LMP)).

701

How lmp works

Other services
client:701lmpresponse client:701lmpresponse

The client sends a request to port 701 and the lmp 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
Well-known (0-1023)
Category
Other services
01 Security

Is port 701 dangerous?

We have no specific security note for port 701. 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 701

ServicePortTransportDescriptionReferenceUpdated
lmp 701 TCP, UDP Link Management Protocol (LMP) RFC 4204 -

// source: IANA service name and port number registry

03 Check it

Which program uses port 701, and is it reachable?

Linux

sudo ss -ltnup 'sport = :701'      # process listening on 701
sudo lsof -nP -i :701

macOS

sudo lsof -nP -i :701

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 701 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 701
netstat -ano | findstr :701

From another machine

nmap -p 701 -sV <host>
sudo nmap -sU -p 701 <host>
nc -zv <host> 701

Block it in the firewall

sudo ufw deny 701/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 701" -Direction Inbound -LocalPort 701 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 701 used for?

Port 701 is assigned by IANA to lmp (Link Management Protocol (LMP)).

Is port 701 TCP or UDP?

Port 701 is registered for TCP and UDP.

Is it safe to open port 701?

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 701 is open?

On Linux run "ss -ltnup 'sport = :701'", on macOS "lsof -nP -i :701", and on Windows "netstat -ano | findstr :701" to see the local process. From another machine, "nmap -p 701 <host>" shows whether it is reachable.

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