CyberHunter
Local dataset, no network
// Other services

Port 1981: p2pQ

Port 1981 is assigned by IANA to p2pq (p2pQ).

1981

How p2pq works

Other services
client:1981p2pqresponse client:1981p2pqresponse

The client sends a request to port 1981 and the p2pq 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 1981 dangerous?

We have no specific security note for port 1981. 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 1981

ServicePortTransportDescriptionReferenceUpdated
p2pq 1981 TCP, UDP p2pQ - -

// source: IANA service name and port number registry

03 Check it

Which program uses port 1981, and is it reachable?

Linux

sudo ss -ltnup 'sport = :1981'      # process listening on 1981
sudo lsof -nP -i :1981

macOS

sudo lsof -nP -i :1981

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 1981 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 1981
netstat -ano | findstr :1981

From another machine

nmap -p 1981 -sV <host>
sudo nmap -sU -p 1981 <host>
nc -zv <host> 1981

Block it in the firewall

sudo ufw deny 1981/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 1981" -Direction Inbound -LocalPort 1981 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 1981 used for?

Port 1981 is assigned by IANA to p2pq (p2pQ).

Is port 1981 TCP or UDP?

Port 1981 is registered for TCP and UDP.

Is it safe to open port 1981?

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 1981 is open?

On Linux run "ss -ltnup 'sport = :1981'", on macOS "lsof -nP -i :1981", and on Windows "netstat -ano | findstr :1981" to see the local process. From another machine, "nmap -p 1981 <host>" shows whether it is reachable.

05 Related
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