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Port 2668 (alarm-clock-c)

IANA assigns port 2668 to alarm-clock-c: Alarm Clock Client.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
alarm-clock-c TCP Alarm Clock Client - -
alarm-clock-c UDP Alarm Clock Client - -

Check what is listening on port 2668

Linux: is anything listening on TCP 2668?
sudo ss -tlnp 'sport = :2668'
Linux: UDP 2668
sudo ss -ulnp 'sport = :2668'
Linux / macOS: which process owns the port
sudo lsof -nP -i :2668
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':2668 '
Windows (Command Prompt)
netstat -ano | findstr :2668
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 2668 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 2668
From Windows
Test-NetConnection HOST -Port 2668
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 2668

Block port 2668 in the firewall

ufw
sudo ufw deny 2668/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 2668 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 2668 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 2668' -Direction Inbound -Protocol TCP -LocalPort 2668 -Action Block
ufw
sudo ufw deny 2668/udp
iptables
sudo iptables -A INPUT -p udp --dport 2668 -j DROP
nftables
sudo nft add rule inet filter input udp dport 2668 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 2668' -Direction Inbound -Protocol UDP -LocalPort 2668 -Action Block

Related ports

2666extensis2667alarm-clock-s2669toad2670tve-announce

All port numbers · Open port checker
Assignment data: IANA port number registry (public domain), retrieved 2026-11-10.