CyberHunter
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// Other services

Port 685: MDC Port Mapper

Port 685 is assigned by IANA to mdc-portmapper (MDC Port Mapper).

685

How mdc-portmapper works

Other services
client:685mdc-portmapperresponse client:685mdc-portmapperresponse

The client sends a request to port 685 and the mdc-portmapper 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
01 Security

Is port 685 dangerous?

We have no specific security note for port 685. 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 685

ServicePortTransportDescriptionReferenceUpdated
mdc-portmapper 685 TCP, UDP MDC Port Mapper - -

// source: IANA service name and port number registry

03 Check it

Which program uses port 685, and is it reachable?

Linux

sudo ss -ltnup 'sport = :685'      # process listening on 685
sudo lsof -nP -i :685

macOS

sudo lsof -nP -i :685

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 685 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 685
netstat -ano | findstr :685

From another machine

nmap -p 685 -sV <host>
sudo nmap -sU -p 685 <host>
nc -zv <host> 685

Block it in the firewall

sudo ufw deny 685/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 685" -Direction Inbound -LocalPort 685 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 685 used for?

Port 685 is assigned by IANA to mdc-portmapper (MDC Port Mapper).

Is port 685 TCP or UDP?

Port 685 is registered for TCP and UDP.

Is it safe to open port 685?

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 685 is open?

On Linux run "ss -ltnup 'sport = :685'", on macOS "lsof -nP -i :685", and on Windows "netstat -ano | findstr :685" to see the local process. From another machine, "nmap -p 685 <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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