HTTPfy

Port 3743 (ipcs-command)

IANA assigns port 3743 to ipcs-command: IP Control Systems Ltd..

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
ipcs-command TCP IP Control Systems Ltd. Paul Anderson -
ipcs-command UDP IP Control Systems Ltd. Paul Anderson -

Registry dates for this port: registered 2003-04.

Check what is listening on port 3743

Linux: is anything listening on TCP 3743?
sudo ss -tlnp 'sport = :3743'
Linux: UDP 3743
sudo ss -ulnp 'sport = :3743'
Linux / macOS: which process owns the port
sudo lsof -nP -i :3743
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':3743 '
Windows (Command Prompt)
netstat -ano | findstr :3743
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 3743 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 3743
From Windows
Test-NetConnection HOST -Port 3743
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 3743

Block port 3743 in the firewall

ufw
sudo ufw deny 3743/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 3743 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 3743 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 3743' -Direction Inbound -Protocol TCP -LocalPort 3743 -Action Block
ufw
sudo ufw deny 3743/udp
iptables
sudo iptables -A INPUT -p udp --dport 3743 -j DROP
nftables
sudo nft add rule inet filter input udp dport 3743 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 3743' -Direction Inbound -Protocol UDP -LocalPort 3743 -Action Block

Related ports

3741wysdma3742cst-port3744sasg3745gw-call-port

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