CyberHunter
LinkedIn profile - Bastien Cordier Email: contact@bastiencordier.pro
// Other services

Port 11751: Intrepid SSL

Port 11751 is assigned by IANA to intrepid-ssl (Intrepid SSL).

11751

How intrepid-ssl works

Other services
client:11751intrepid-sslresponse client:11751intrepid-sslresponse

The client sends a request to port 11751 and the intrepid-ssl 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
Registered (1024-49151)
Category
Other services
01 Security

Is port 11751 dangerous?

We have no specific security note for port 11751. 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 11751

ServicePortTransportDescriptionReferenceUpdated
intrepid-ssl 11751 TCP, UDP Intrepid SSL - 2003-03

// source: IANA service name and port number registry

03 Check it

Which program uses port 11751, and is it reachable?

Linux

sudo ss -ltnup 'sport = :11751'      # process listening on 11751
sudo lsof -nP -i :11751

macOS

sudo lsof -nP -i :11751

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 11751 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 11751
netstat -ano | findstr :11751

From another machine

nmap -p 11751 -sV <host>
sudo nmap -sU -p 11751 <host>
nc -zv <host> 11751

Block it in the firewall

sudo ufw deny 11751/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 11751" -Direction Inbound -LocalPort 11751 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 11751 used for?

Port 11751 is assigned by IANA to intrepid-ssl (Intrepid SSL).

Is port 11751 TCP or UDP?

Port 11751 is registered for TCP and UDP.

Is it safe to open port 11751?

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 11751 is open?

On Linux run "ss -ltnup 'sport = :11751'", on macOS "lsof -nP -i :11751", and on Windows "netstat -ano | findstr :11751" to see the local process. From another machine, "nmap -p 11751 <host>" shows whether it is reachable.

05 Related
:4444 Metasploit default / krb524 tcp · udp · high risk :31337 Back Orifice / elite tcp · udp · high risk :1 TCP Port Service Multiplexer tcp · udp :5 Remote Job Entry 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

Latest vulnerability news

All news