CyberHunter
Local dataset, no network
// Other services

Port 5420: Cylink-C

Port 5420 is assigned by IANA to cylink-c (Cylink-C).

5420

How cylink-c works

Other services
client:5420cylink-cresponse client:5420cylink-cresponse

The client sends a request to port 5420 and the cylink-c 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 5420 dangerous?

We have no specific security note for port 5420. 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 5420

ServicePortTransportDescriptionReferenceUpdated
cylink-c 5420 TCP, UDP Cylink-C - -

// source: IANA service name and port number registry

03 Check it

Which program uses port 5420, and is it reachable?

Linux

sudo ss -ltnup 'sport = :5420'      # process listening on 5420
sudo lsof -nP -i :5420

macOS

sudo lsof -nP -i :5420

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 5420 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 5420
netstat -ano | findstr :5420

From another machine

nmap -p 5420 -sV <host>
sudo nmap -sU -p 5420 <host>
nc -zv <host> 5420

Block it in the firewall

sudo ufw deny 5420/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 5420" -Direction Inbound -LocalPort 5420 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 5420 used for?

Port 5420 is assigned by IANA to cylink-c (Cylink-C).

Is port 5420 TCP or UDP?

Port 5420 is registered for TCP and UDP.

Is it safe to open port 5420?

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 5420 is open?

On Linux run "ss -ltnup 'sport = :5420'", on macOS "lsof -nP -i :5420", and on Windows "netstat -ano | findstr :5420" to see the local process. From another machine, "nmap -p 5420 <host>" shows whether it is reachable.

05 Related
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