HTTPfy

Port 27504 (kopek-httphead)

IANA assigns port 27504 to kopek-httphead: Kopek HTTP Head Port.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
kopek-httphead TCP Kopek HTTP Head Port Sten H Danielsen -
kopek-httphead UDP Kopek HTTP Head Port Sten H Danielsen -

Registry dates for this port: registered 2002-07.

Check what is listening on port 27504

Linux: is anything listening on TCP 27504?
sudo ss -tlnp 'sport = :27504'
Linux: UDP 27504
sudo ss -ulnp 'sport = :27504'
Linux / macOS: which process owns the port
sudo lsof -nP -i :27504
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':27504 '
Windows (Command Prompt)
netstat -ano | findstr :27504
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 27504 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 27504
From Windows
Test-NetConnection HOST -Port 27504
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 27504

Block port 27504 in the firewall

ufw
sudo ufw deny 27504/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 27504 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 27504 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 27504' -Direction Inbound -Protocol TCP -LocalPort 27504 -Action Block
ufw
sudo ufw deny 27504/udp
iptables
sudo iptables -A INPUT -p udp --dport 27504 -j DROP
nftables
sudo nft add rule inet filter input udp dport 27504 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 27504' -Direction Inbound -Protocol UDP -LocalPort 27504 -Action Block

Related ports

27345imagepump27442jesmsjc27782ars-vista27876astrolink

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