CyberHunter
Local dataset, no network
// Other services

Port 45: Message Processing Module [recv]

Port 45 is assigned by IANA to mpm (Message Processing Module [recv]).

45

How mpm works

Other services
client:45mpmresponse client:45mpmresponse

The client sends a request to port 45 and the mpm 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 45 dangerous?

We have no specific security note for port 45. 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 45

ServicePortTransportDescriptionReferenceUpdated
mpm 45 TCP, UDP Message Processing Module [recv] - -

// source: IANA service name and port number registry

03 Check it

Which program uses port 45, and is it reachable?

Linux

sudo ss -ltnup 'sport = :45'      # process listening on 45
sudo lsof -nP -i :45

macOS

sudo lsof -nP -i :45

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 45 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 45
netstat -ano | findstr :45

From another machine

nmap -p 45 -sV <host>
sudo nmap -sU -p 45 <host>
nc -zv <host> 45

Block it in the firewall

sudo ufw deny 45/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 45" -Direction Inbound -LocalPort 45 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 45 used for?

Port 45 is assigned by IANA to mpm (Message Processing Module [recv]).

Is port 45 TCP or UDP?

Port 45 is registered for TCP and UDP.

Is it safe to open port 45?

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 45 is open?

On Linux run "ss -ltnup 'sport = :45'", on macOS "lsof -nP -i :45", and on Windows "netstat -ano | findstr :45" to see the local process. From another machine, "nmap -p 45 <host>" shows whether it is reachable.

05 Related
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