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// Other services

Port 2668: Alarm Clock Client

Port 2668 is assigned by IANA to alarm-clock-c (Alarm Clock Client).

2668

How alarm-clock-c works

Other services
client:2668alarm-clock-cresponse client:2668alarm-clock-cresponse

The client sends a request to port 2668 and the alarm-clock-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 2668 dangerous?

We have no specific security note for port 2668. 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 2668

ServicePortTransportDescriptionReferenceUpdated
alarm-clock-c 2668 TCP, UDP Alarm Clock Client - -

// source: IANA service name and port number registry

03 Check it

Which program uses port 2668, and is it reachable?

Linux

sudo ss -ltnup 'sport = :2668'      # process listening on 2668
sudo lsof -nP -i :2668

macOS

sudo lsof -nP -i :2668

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 2668 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 2668
netstat -ano | findstr :2668

From another machine

nmap -p 2668 -sV <host>
sudo nmap -sU -p 2668 <host>
nc -zv <host> 2668

Block it in the firewall

sudo ufw deny 2668/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 2668" -Direction Inbound -LocalPort 2668 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 2668 used for?

Port 2668 is assigned by IANA to alarm-clock-c (Alarm Clock Client).

Is port 2668 TCP or UDP?

Port 2668 is registered for TCP and UDP.

Is it safe to open port 2668?

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 2668 is open?

On Linux run "ss -ltnup 'sport = :2668'", on macOS "lsof -nP -i :2668", and on Windows "netstat -ano | findstr :2668" to see the local process. From another machine, "nmap -p 2668 <host>" shows whether it is reachable.

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