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Port 3786 (upstriggervsw)

IANA assigns port 3786 to upstriggervsw: VSW Upstrigger port.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
upstriggervsw TCP VSW Upstrigger port Mark Tim Junghanns -
upstriggervsw UDP VSW Upstrigger port Mark Tim Junghanns -

Registry dates for this port: registered 2003-07.

Check what is listening on port 3786

Linux: is anything listening on TCP 3786?
sudo ss -tlnp 'sport = :3786'
Linux: UDP 3786
sudo ss -ulnp 'sport = :3786'
Linux / macOS: which process owns the port
sudo lsof -nP -i :3786
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':3786 '
Windows (Command Prompt)
netstat -ano | findstr :3786
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 3786 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 3786
From Windows
Test-NetConnection HOST -Port 3786
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 3786

Block port 3786 in the firewall

ufw
sudo ufw deny 3786/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 3786 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 3786 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 3786' -Direction Inbound -Protocol TCP -LocalPort 3786 -Action Block
ufw
sudo ufw deny 3786/udp
iptables
sudo iptables -A INPUT -p udp --dport 3786 -j DROP
nftables
sudo nft add rule inet filter input udp dport 3786 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 3786' -Direction Inbound -Protocol UDP -LocalPort 3786 -Action Block

Related ports

3784bfd-control3785bfd-echo3787fintrx3788isrp-port

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