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// Other services

Port 1639: cert-initiator

Port 1639 is assigned by IANA to cert-initiator (cert-initiator).

1639

How cert-initiator works

Other services
client:1639cert-initiatorresponse client:1639cert-initiatorresponse

The client sends a request to port 1639 and the cert-initiator 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 1639 dangerous?

We have no specific security note for port 1639. 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 1639

ServicePortTransportDescriptionReferenceUpdated
cert-initiator 1639 TCP, UDP cert-initiator - -

// source: IANA service name and port number registry

03 Check it

Which program uses port 1639, and is it reachable?

Linux

sudo ss -ltnup 'sport = :1639'      # process listening on 1639
sudo lsof -nP -i :1639

macOS

sudo lsof -nP -i :1639

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 1639 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 1639
netstat -ano | findstr :1639

From another machine

nmap -p 1639 -sV <host>
sudo nmap -sU -p 1639 <host>
nc -zv <host> 1639

Block it in the firewall

sudo ufw deny 1639/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 1639" -Direction Inbound -LocalPort 1639 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 1639 used for?

Port 1639 is assigned by IANA to cert-initiator (cert-initiator).

Is port 1639 TCP or UDP?

Port 1639 is registered for TCP and UDP.

Is it safe to open port 1639?

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 1639 is open?

On Linux run "ss -ltnup 'sport = :1639'", on macOS "lsof -nP -i :1639", and on Windows "netstat -ano | findstr :1639" to see the local process. From another machine, "nmap -p 1639 <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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