HTTPfy

Port 3746 (linktest)

IANA assigns port 3746 to linktest: LXPRO.COM LinkTest.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
linktest TCP LXPRO.COM LinkTest - -
linktest UDP LXPRO.COM LinkTest - -

Check what is listening on port 3746

Linux: is anything listening on TCP 3746?
sudo ss -tlnp 'sport = :3746'
Linux: UDP 3746
sudo ss -ulnp 'sport = :3746'
Linux / macOS: which process owns the port
sudo lsof -nP -i :3746
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':3746 '
Windows (Command Prompt)
netstat -ano | findstr :3746
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 3746 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 3746
From Windows
Test-NetConnection HOST -Port 3746
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 3746

Block port 3746 in the firewall

ufw
sudo ufw deny 3746/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 3746 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 3746 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 3746' -Direction Inbound -Protocol TCP -LocalPort 3746 -Action Block
ufw
sudo ufw deny 3746/udp
iptables
sudo iptables -A INPUT -p udp --dport 3746 -j DROP
nftables
sudo nft add rule inet filter input udp dport 3746 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 3746' -Direction Inbound -Protocol UDP -LocalPort 3746 -Action Block

Related ports

3744sasg3745gw-call-port3747linktest-s3748webdata

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