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Port 2122 (caupc-remote)

IANA assigns port 2122 to caupc-remote: CauPC Remote Control.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
caupc-remote TCP CauPC Remote Control Environics Oy -
caupc-remote UDP CauPC Remote Control Environics Oy -

Check what is listening on port 2122

Linux: is anything listening on TCP 2122?
sudo ss -tlnp 'sport = :2122'
Linux: UDP 2122
sudo ss -ulnp 'sport = :2122'
Linux / macOS: which process owns the port
sudo lsof -nP -i :2122
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':2122 '
Windows (Command Prompt)
netstat -ano | findstr :2122
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 2122 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 2122
From Windows
Test-NetConnection HOST -Port 2122
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 2122

Block port 2122 in the firewall

ufw
sudo ufw deny 2122/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 2122 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 2122 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 2122' -Direction Inbound -Protocol TCP -LocalPort 2122 -Action Block
ufw
sudo ufw deny 2122/udp
iptables
sudo iptables -A INPUT -p udp --dport 2122 -j DROP
nftables
sudo nft add rule inet filter input udp dport 2122 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 2122' -Direction Inbound -Protocol UDP -LocalPort 2122 -Action Block

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