CyberHunter
Local dataset, no network
// Other services

Port 9876: Session Director

Port 9876 is assigned by IANA to sd (Session Director).

9876

How sd works

Other services
client:9876sdresponse client:9876sdresponse

The client sends a request to port 9876 and the sd service answers.

Transport
TCP
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 9876 dangerous?

We have no specific security note for port 9876. 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 9876

ServicePortTransportDescriptionReferenceUpdated
sd 9876 TCP Session Director - -

// source: IANA service name and port number registry

03 Check it

Which program uses port 9876, and is it reachable?

Linux

sudo ss -ltnup 'sport = :9876'      # process listening on 9876
sudo lsof -nP -i :9876

macOS

sudo lsof -nP -i :9876

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 9876 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 9876
netstat -ano | findstr :9876

From another machine

nmap -p 9876 -sV <host>
nc -zv <host> 9876

Block it in the firewall

sudo ufw deny 9876/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 9876" -Direction Inbound -LocalPort 9876 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 9876 used for?

Port 9876 is assigned by IANA to sd (Session Director).

Is port 9876 TCP or UDP?

Port 9876 is registered for TCP.

Is it safe to open port 9876?

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 9876 is open?

On Linux run "ss -ltnup 'sport = :9876'", on macOS "lsof -nP -i :9876", and on Windows "netstat -ano | findstr :9876" to see the local process. From another machine, "nmap -p 9876 <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

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