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// Other services

Port 770:

Port 770 is assigned by IANA to cadlock ().

770

How cadlock works

Other services
client:770cadlockresponse client:770cadlockresponse

The client sends a request to port 770 and the cadlock 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
Well-known (0-1023)
Category
Other services
01 Security

Is port 770 dangerous?

We have no specific security note for port 770. 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 770

ServicePortTransportDescriptionReferenceUpdated
cadlock 770 TCP, UDP - -

// source: IANA service name and port number registry

03 Check it

Which program uses port 770, and is it reachable?

Linux

sudo ss -ltnup 'sport = :770'      # process listening on 770
sudo lsof -nP -i :770

macOS

sudo lsof -nP -i :770

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 770 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 770
netstat -ano | findstr :770

From another machine

nmap -p 770 -sV <host>
sudo nmap -sU -p 770 <host>
nc -zv <host> 770

Block it in the firewall

sudo ufw deny 770/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 770" -Direction Inbound -LocalPort 770 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 770 used for?

Port 770 is assigned by IANA to cadlock ().

Is port 770 TCP or UDP?

Port 770 is registered for TCP and UDP.

Is it safe to open port 770?

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 770 is open?

On Linux run "ss -ltnup 'sport = :770'", on macOS "lsof -nP -i :770", and on Windows "netstat -ano | findstr :770" to see the local process. From another machine, "nmap -p 770 <host>" shows whether it is reachable.

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