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Port 4378 (cp-spxdpy)

IANA assigns port 4378 to cp-spxdpy: Cambridge Pixel SPx Display.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
cp-spxdpy TCP Cambridge Pixel SPx Display Richard Warren -
cp-spxdpy UDP Cambridge Pixel SPx Display Richard Warren -

Registry dates for this port: registered 2007-07-05.

Check what is listening on port 4378

Linux: is anything listening on TCP 4378?
sudo ss -tlnp 'sport = :4378'
Linux: UDP 4378
sudo ss -ulnp 'sport = :4378'
Linux / macOS: which process owns the port
sudo lsof -nP -i :4378
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':4378 '
Windows (Command Prompt)
netstat -ano | findstr :4378
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 4378 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 4378
From Windows
Test-NetConnection HOST -Port 4378
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 4378

Block port 4378 in the firewall

ufw
sudo ufw deny 4378/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 4378 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 4378 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 4378' -Direction Inbound -Protocol TCP -LocalPort 4378 -Action Block
ufw
sudo ufw deny 4378/udp
iptables
sudo iptables -A INPUT -p udp --dport 4378 -j DROP
nftables
sudo nft add rule inet filter input udp dport 4378 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 4378' -Direction Inbound -Protocol UDP -LocalPort 4378 -Action Block

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4376bip4377cp-spxsvr4379ctdb4389xandros-cms

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Assignment data: IANA port number registry (public domain), retrieved 2026-11-10.