CyberHunter
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// Other services

Port 158: PCMail Server

Port 158 is assigned by IANA to pcmail-srv (PCMail Server).

158

How pcmail-srv works

Other services
client:158pcmail-srvresponse client:158pcmail-srvresponse

The client sends a request to port 158 and the pcmail-srv 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 158 dangerous?

We have no specific security note for port 158. 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 158

ServicePortTransportDescriptionReferenceUpdated
pcmail-srv 158 TCP, UDP PCMail Server - -

// source: IANA service name and port number registry

03 Check it

Which program uses port 158, and is it reachable?

Linux

sudo ss -ltnup 'sport = :158'      # process listening on 158
sudo lsof -nP -i :158

macOS

sudo lsof -nP -i :158

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 158 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 158
netstat -ano | findstr :158

From another machine

nmap -p 158 -sV <host>
sudo nmap -sU -p 158 <host>
nc -zv <host> 158

Block it in the firewall

sudo ufw deny 158/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 158" -Direction Inbound -LocalPort 158 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 158 used for?

Port 158 is assigned by IANA to pcmail-srv (PCMail Server).

Is port 158 TCP or UDP?

Port 158 is registered for TCP and UDP.

Is it safe to open port 158?

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 158 is open?

On Linux run "ss -ltnup 'sport = :158'", on macOS "lsof -nP -i :158", and on Windows "netstat -ano | findstr :158" to see the local process. From another machine, "nmap -p 158 <host>" shows whether it is reachable.

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