CyberHunter
Local dataset, no network
// Other services

Port 1648: concurrent-lm

Port 1648 is assigned by IANA to concurrent-lm (concurrent-lm).

1648

How concurrent-lm works

Other services
client:1648concurrent-lmresponse client:1648concurrent-lmresponse

The client sends a request to port 1648 and the concurrent-lm 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 1648 dangerous?

We have no specific security note for port 1648. 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 1648

ServicePortTransportDescriptionReferenceUpdated
concurrent-lm 1648 TCP, UDP concurrent-lm - -

// source: IANA service name and port number registry

03 Check it

Which program uses port 1648, and is it reachable?

Linux

sudo ss -ltnup 'sport = :1648'      # process listening on 1648
sudo lsof -nP -i :1648

macOS

sudo lsof -nP -i :1648

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 1648 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 1648
netstat -ano | findstr :1648

From another machine

nmap -p 1648 -sV <host>
sudo nmap -sU -p 1648 <host>
nc -zv <host> 1648

Block it in the firewall

sudo ufw deny 1648/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 1648" -Direction Inbound -LocalPort 1648 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 1648 used for?

Port 1648 is assigned by IANA to concurrent-lm (concurrent-lm).

Is port 1648 TCP or UDP?

Port 1648 is registered for TCP and UDP.

Is it safe to open port 1648?

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 1648 is open?

On Linux run "ss -ltnup 'sport = :1648'", on macOS "lsof -nP -i :1648", and on Windows "netstat -ano | findstr :1648" to see the local process. From another machine, "nmap -p 1648 <host>" shows whether it is reachable.

05 Related
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