HTTPfy

Port 4187 (csc-proxy, csc_proxy)

IANA assigns port 4187 to csc-proxy, csc_proxy: Cascade Proxy IANA assigned this well-formed service name as a replacement for "csc_proxy"..

Registered (user) port, 1024-49151 TCP

IANA assignment

Service nameProtoDescriptionAssigneeReference
csc-proxy TCP Cascade Proxy IANA assigned this well-formed service name as a replacement for "csc_proxy". Matt Craighead -
csc_proxy TCP Cascade Proxy
This entry is an alias to "csc-proxy". This entry is now historic, not usable for use with many common service discovery mechanisms. Matt Craighead -

Registry dates for this port: registered 2008-09-11.

Check what is listening on port 4187

Linux: is anything listening on TCP 4187?
sudo ss -tlnp 'sport = :4187'
Linux / macOS: which process owns the port
sudo lsof -nP -i :4187
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':4187 '
Windows (Command Prompt)
netstat -ano | findstr :4187
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 4187 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 4187
From Windows
Test-NetConnection HOST -Port 4187

Block port 4187 in the firewall

ufw
sudo ufw deny 4187/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 4187 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 4187 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 4187' -Direction Inbound -Protocol TCP -LocalPort 4187 -Action Block

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