- 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.
Port 5: Remote Job Entry
Port 5 is assigned by IANA to rje (Remote Job Entry).
5
How rje works
Other servicesThe client sends a request to port 5 and the rje 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
Is port 5 dangerous?
We have no specific security note for port 5. Its risk depends on the program actually listening on it. General advice for other services services:
IANA registry entries for port 5
| Service | Port | Transport | Description | Reference | Updated |
|---|---|---|---|---|---|
| rje | 5 | TCP, UDP | Remote Job Entry | - | - |
// source: IANA service name and port number registry
Which program uses port 5, and is it reachable?
Linux
sudo ss -ltnup 'sport = :5' # process listening on 5
sudo lsof -nP -i :5macOS
sudo lsof -nP -i :5
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 5 -State Listen | Select LocalAddress, OwningProcess Get-NetUDPEndpoint -LocalPort 5 netstat -ano | findstr :5
From another machine
nmap -p 5 -sV <host> sudo nmap -sU -p 5 <host> nc -zv <host> 5
Block it in the firewall
sudo ufw deny 5/tcp # Linux (ufw) New-NetFirewallRule -DisplayName "Block 5" -Direction Inbound -LocalPort 5 -Protocol TCP -Action Block # Windows
What is port 5 used for?
Port 5 is assigned by IANA to rje (Remote Job Entry).
Is port 5 TCP or UDP?
Port 5 is registered for TCP and UDP.
Is it safe to open port 5?
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 5 is open?
On Linux run "ss -ltnup 'sport = :5'", on macOS "lsof -nP -i :5", and on Windows "netstat -ano | findstr :5" to see the local process. From another machine, "nmap -p 5 <host>" shows whether it is reachable.
Other other services ports
:4444 Metasploit default / krb524 tcp · udp · high risk :31337 Back Orifice / elite tcp · udp · high risk :1 TCP Port Service Multiplexer tcp · udp :9 Discard tcp · udp · sctp · dccp :11 Active Users tcp · udp :17 Quote of the Day tcp · udp :18 Message Send Protocol (historic) tcp · udp :27 NSW User System FE tcp · udp