CyberHunter
Local dataset, no network
// Other services

Port 6456: SKIP Certificate Send

Port 6456 is assigned by IANA to skip-cert-send (SKIP Certificate Send).

6456

How skip-cert-send works

Other services
client:6456skip-cert-sendresponse client:6456skip-cert-sendresponse

The client sends a request to port 6456 and the skip-cert-send 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 6456 dangerous?

We have no specific security note for port 6456. 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 6456

ServicePortTransportDescriptionReferenceUpdated
skip-cert-send 6456 TCP, UDP SKIP Certificate Send - -

// source: IANA service name and port number registry

03 Check it

Which program uses port 6456, and is it reachable?

Linux

sudo ss -ltnup 'sport = :6456'      # process listening on 6456
sudo lsof -nP -i :6456

macOS

sudo lsof -nP -i :6456

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 6456 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 6456
netstat -ano | findstr :6456

From another machine

nmap -p 6456 -sV <host>
sudo nmap -sU -p 6456 <host>
nc -zv <host> 6456

Block it in the firewall

sudo ufw deny 6456/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 6456" -Direction Inbound -LocalPort 6456 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 6456 used for?

Port 6456 is assigned by IANA to skip-cert-send (SKIP Certificate Send).

Is port 6456 TCP or UDP?

Port 6456 is registered for TCP and UDP.

Is it safe to open port 6456?

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 6456 is open?

On Linux run "ss -ltnup 'sport = :6456'", on macOS "lsof -nP -i :6456", and on Windows "netstat -ano | findstr :6456" to see the local process. From another machine, "nmap -p 6456 <host>" shows whether it is reachable.

05 Related
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