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// Other services

Port 7777: cbt

Port 7777 is assigned by IANA to cbt (cbt).

7777

How cbt works

Other services
client:7777cbtresponse client:7777cbtresponse

The client sends a request to port 7777 and the cbt 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 7777 dangerous?

We have no specific security note for port 7777. 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 7777

ServicePortTransportDescriptionReferenceUpdated
cbt 7777 TCP, UDP cbt
Reported: Known Unauthorized Use on port 7777
 - -

// source: IANA service name and port number registry

03 Check it

Which program uses port 7777, and is it reachable?

Linux

sudo ss -ltnup 'sport = :7777'      # process listening on 7777
sudo lsof -nP -i :7777

macOS

sudo lsof -nP -i :7777

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 7777 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 7777
netstat -ano | findstr :7777

From another machine

nmap -p 7777 -sV <host>
sudo nmap -sU -p 7777 <host>
nc -zv <host> 7777

Block it in the firewall

sudo ufw deny 7777/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 7777" -Direction Inbound -LocalPort 7777 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 7777 used for?

Port 7777 is assigned by IANA to cbt (cbt).

Is port 7777 TCP or UDP?

Port 7777 is registered for TCP and UDP.

Is it safe to open port 7777?

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 7777 is open?

On Linux run "ss -ltnup 'sport = :7777'", on macOS "lsof -nP -i :7777", and on Windows "netstat -ano | findstr :7777" to see the local process. From another machine, "nmap -p 7777 <host>" shows whether it is reachable.

05 Related
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