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// Other services

Port 2421: G-Talk

Port 2421 is assigned by IANA to g-talk (G-Talk).

2421

How g-talk works

Other services
client:2421g-talkresponse client:2421g-talkresponse

The client sends a request to port 2421 and the g-talk 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 2421 dangerous?

We have no specific security note for port 2421. 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 2421

ServicePortTransportDescriptionReferenceUpdated
g-talk 2421 TCP, UDP G-Talk - -

// source: IANA service name and port number registry

03 Check it

Which program uses port 2421, and is it reachable?

Linux

sudo ss -ltnup 'sport = :2421'      # process listening on 2421
sudo lsof -nP -i :2421

macOS

sudo lsof -nP -i :2421

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 2421 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 2421
netstat -ano | findstr :2421

From another machine

nmap -p 2421 -sV <host>
sudo nmap -sU -p 2421 <host>
nc -zv <host> 2421

Block it in the firewall

sudo ufw deny 2421/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 2421" -Direction Inbound -LocalPort 2421 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 2421 used for?

Port 2421 is assigned by IANA to g-talk (G-Talk).

Is port 2421 TCP or UDP?

Port 2421 is registered for TCP and UDP.

Is it safe to open port 2421?

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 2421 is open?

On Linux run "ss -ltnup 'sport = :2421'", on macOS "lsof -nP -i :2421", and on Windows "netstat -ano | findstr :2421" to see the local process. From another machine, "nmap -p 2421 <host>" shows whether it is reachable.

05 Related
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