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// Other services

Port 6455: SKIP Certificate Receive

Port 6455 is assigned by IANA to skip-cert-recv (SKIP Certificate Receive).

6455

How skip-cert-recv works

Other services
client:6455skip-cert-recvresponse client:6455skip-cert-recvresponse

The client sends a request to port 6455 and the skip-cert-recv 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 6455 dangerous?

We have no specific security note for port 6455. 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 6455

ServicePortTransportDescriptionReferenceUpdated
skip-cert-recv 6455 TCP, UDP SKIP Certificate Receive - -

// source: IANA service name and port number registry

03 Check it

Which program uses port 6455, and is it reachable?

Linux

sudo ss -ltnup 'sport = :6455'      # process listening on 6455
sudo lsof -nP -i :6455

macOS

sudo lsof -nP -i :6455

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 6455 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 6455
netstat -ano | findstr :6455

From another machine

nmap -p 6455 -sV <host>
sudo nmap -sU -p 6455 <host>
nc -zv <host> 6455

Block it in the firewall

sudo ufw deny 6455/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 6455" -Direction Inbound -LocalPort 6455 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 6455 used for?

Port 6455 is assigned by IANA to skip-cert-recv (SKIP Certificate Receive).

Is port 6455 TCP or UDP?

Port 6455 is registered for TCP and UDP.

Is it safe to open port 6455?

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 6455 is open?

On Linux run "ss -ltnup 'sport = :6455'", on macOS "lsof -nP -i :6455", and on Windows "netstat -ano | findstr :6455" to see the local process. From another machine, "nmap -p 6455 <host>" shows whether it is reachable.

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