CyberHunter
Local dataset, no network
// Other services

Port 2673: First Call 42

Port 2673 is assigned by IANA to firstcall42 (First Call 42).

2673

How firstcall42 works

Other services
client:2673firstcall42response client:2673firstcall42response

The client sends a request to port 2673 and the firstcall42 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 2673 dangerous?

We have no specific security note for port 2673. 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 2673

ServicePortTransportDescriptionReferenceUpdated
firstcall42 2673 TCP, UDP First Call 42 - -

// source: IANA service name and port number registry

03 Check it

Which program uses port 2673, and is it reachable?

Linux

sudo ss -ltnup 'sport = :2673'      # process listening on 2673
sudo lsof -nP -i :2673

macOS

sudo lsof -nP -i :2673

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 2673 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 2673
netstat -ano | findstr :2673

From another machine

nmap -p 2673 -sV <host>
sudo nmap -sU -p 2673 <host>
nc -zv <host> 2673

Block it in the firewall

sudo ufw deny 2673/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 2673" -Direction Inbound -LocalPort 2673 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 2673 used for?

Port 2673 is assigned by IANA to firstcall42 (First Call 42).

Is port 2673 TCP or UDP?

Port 2673 is registered for TCP and UDP.

Is it safe to open port 2673?

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 2673 is open?

On Linux run "ss -ltnup 'sport = :2673'", on macOS "lsof -nP -i :2673", and on Windows "netstat -ano | findstr :2673" to see the local process. From another machine, "nmap -p 2673 <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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