CyberHunter
Local dataset, no network
// Other services

Port 505: mailbox-lm

Port 505 is assigned by IANA to mailbox-lm (mailbox-lm).

505

How mailbox-lm works

Other services
client:505mailbox-lmresponse client:505mailbox-lmresponse

The client sends a request to port 505 and the mailbox-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
Well-known (0-1023)
Category
Other services
01 Security

Is port 505 dangerous?

We have no specific security note for port 505. 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 505

ServicePortTransportDescriptionReferenceUpdated
mailbox-lm 505 TCP, UDP mailbox-lm - -

// source: IANA service name and port number registry

03 Check it

Which program uses port 505, and is it reachable?

Linux

sudo ss -ltnup 'sport = :505'      # process listening on 505
sudo lsof -nP -i :505

macOS

sudo lsof -nP -i :505

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 505 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 505
netstat -ano | findstr :505

From another machine

nmap -p 505 -sV <host>
sudo nmap -sU -p 505 <host>
nc -zv <host> 505

Block it in the firewall

sudo ufw deny 505/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 505" -Direction Inbound -LocalPort 505 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 505 used for?

Port 505 is assigned by IANA to mailbox-lm (mailbox-lm).

Is port 505 TCP or UDP?

Port 505 is registered for TCP and UDP.

Is it safe to open port 505?

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 505 is open?

On Linux run "ss -ltnup 'sport = :505'", on macOS "lsof -nP -i :505", and on Windows "netstat -ano | findstr :505" to see the local process. From another machine, "nmap -p 505 <host>" shows whether it is reachable.

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