HTTPfy

Port 8400 (cvd)

IANA assigns port 8400 to cvd.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
cvd TCP cvd Aaron Bilbrey -
cvd UDP cvd Aaron Bilbrey -

Check what is listening on port 8400

Linux: is anything listening on TCP 8400?
sudo ss -tlnp 'sport = :8400'
Linux: UDP 8400
sudo ss -ulnp 'sport = :8400'
Linux / macOS: which process owns the port
sudo lsof -nP -i :8400
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':8400 '
Windows (Command Prompt)
netstat -ano | findstr :8400
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 8400 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 8400
From Windows
Test-NetConnection HOST -Port 8400
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 8400

Block port 8400 in the firewall

ufw
sudo ufw deny 8400/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 8400 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 8400 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 8400' -Direction Inbound -Protocol TCP -LocalPort 8400 -Action Block
ufw
sudo ufw deny 8400/udp
iptables
sudo iptables -A INPUT -p udp --dport 8400 -j DROP
nftables
sudo nft add rule inet filter input udp dport 8400 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 8400' -Direction Inbound -Protocol UDP -LocalPort 8400 -Action Block

Related ports

8383m2mservices8384marathontp8401sabarsd8402abarsd

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