CyberHunter
Local dataset, no network
// Other services

Port 5091: Context Transfer Protocol

Port 5091 is assigned by IANA to cxtp (Context Transfer Protocol).

5091

How cxtp works

Other services
client:5091cxtpresponse client:5091cxtpresponse

The client sends a request to port 5091 and the cxtp service answers.

Transport
SCTP
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 5091 dangerous?

We have no specific security note for port 5091. 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 5091

ServicePortTransportDescriptionReferenceUpdated
cxtp 5091 SCTP Context Transfer Protocol RFC 4065 2005-07

// source: IANA service name and port number registry

03 Check it

Which program uses port 5091, and is it reachable?

Linux

sudo ss -ltnup 'sport = :5091'      # process listening on 5091
sudo lsof -nP -i :5091

macOS

sudo lsof -nP -i :5091

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 5091 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 5091
netstat -ano | findstr :5091

From another machine

nmap -p 5091 -sV <host>
nc -zv <host> 5091

Block it in the firewall

sudo ufw deny 5091/sctp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 5091" -Direction Inbound -LocalPort 5091 -Protocol SCTP -Action Block  # Windows
04 FAQ
What is port 5091 used for?

Port 5091 is assigned by IANA to cxtp (Context Transfer Protocol).

Is port 5091 TCP or UDP?

Port 5091 is registered for SCTP.

Is it safe to open port 5091?

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 5091 is open?

On Linux run "ss -ltnup 'sport = :5091'", on macOS "lsof -nP -i :5091", and on Windows "netstat -ano | findstr :5091" to see the local process. From another machine, "nmap -p 5091 <host>" shows whether it is reachable.

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