CyberHunter
Local dataset, no network
// Other services

Port 451: Cray Network Semaphore server

Port 451 is assigned by IANA to sfs-smp-net (Cray Network Semaphore server).

451

How sfs-smp-net works

Other services
client:451sfs-smp-netresponse client:451sfs-smp-netresponse

The client sends a request to port 451 and the sfs-smp-net 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 451 dangerous?

We have no specific security note for port 451. 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 451

ServicePortTransportDescriptionReferenceUpdated
sfs-smp-net 451 TCP, UDP Cray Network Semaphore server - -

// source: IANA service name and port number registry

03 Check it

Which program uses port 451, and is it reachable?

Linux

sudo ss -ltnup 'sport = :451'      # process listening on 451
sudo lsof -nP -i :451

macOS

sudo lsof -nP -i :451

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 451 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 451
netstat -ano | findstr :451

From another machine

nmap -p 451 -sV <host>
sudo nmap -sU -p 451 <host>
nc -zv <host> 451

Block it in the firewall

sudo ufw deny 451/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 451" -Direction Inbound -LocalPort 451 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 451 used for?

Port 451 is assigned by IANA to sfs-smp-net (Cray Network Semaphore server).

Is port 451 TCP or UDP?

Port 451 is registered for TCP and UDP.

Is it safe to open port 451?

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 451 is open?

On Linux run "ss -ltnup 'sport = :451'", on macOS "lsof -nP -i :451", and on Windows "netstat -ano | findstr :451" to see the local process. From another machine, "nmap -p 451 <host>" shows whether it is reachable.

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