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// Other services

Port 5786: redundancy notification

Port 5786 is assigned by IANA to cisco-redu (redundancy notification).

5786

How cisco-redu works

Other services
client:5786cisco-reduresponse client:5786cisco-reduresponse

The client sends a request to port 5786 and the cisco-redu service answers.

Transport
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 5786 dangerous?

We have no specific security note for port 5786. 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 5786

ServicePortTransportDescriptionReferenceUpdated
cisco-redu 5786 UDP redundancy notification - 2010-02-04
-5786-Reserved--

// source: IANA service name and port number registry

03 Check it

Which program uses port 5786, and is it reachable?

Linux

sudo ss -ltnup 'sport = :5786'      # process listening on 5786
sudo lsof -nP -i :5786

macOS

sudo lsof -nP -i :5786

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 5786 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 5786
netstat -ano | findstr :5786

From another machine

nmap -p 5786 -sV <host>
sudo nmap -sU -p 5786 <host>
nc -zv <host> 5786

Block it in the firewall

sudo ufw deny 5786/udp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 5786" -Direction Inbound -LocalPort 5786 -Protocol UDP -Action Block  # Windows
04 FAQ
What is port 5786 used for?

Port 5786 is assigned by IANA to cisco-redu (redundancy notification).

Is port 5786 TCP or UDP?

Port 5786 is registered for UDP.

Is it safe to open port 5786?

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 5786 is open?

On Linux run "ss -ltnup 'sport = :5786'", on macOS "lsof -nP -i :5786", and on Windows "netstat -ano | findstr :5786" to see the local process. From another machine, "nmap -p 5786 <host>" shows whether it is reachable.

05 Related
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