HTTPfy

Port 3849 (spw-dnspreload)

IANA assigns port 3849 to spw-dnspreload: SPACEWAY DNS Preload.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
spw-dnspreload TCP SPACEWAY DNS Preload Daniel Friedman -
spw-dnspreload UDP SPACEWAY DNS Preload Daniel Friedman -

Registry dates for this port: registered 2003-08.

Check what is listening on port 3849

Linux: is anything listening on TCP 3849?
sudo ss -tlnp 'sport = :3849'
Linux: UDP 3849
sudo ss -ulnp 'sport = :3849'
Linux / macOS: which process owns the port
sudo lsof -nP -i :3849
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':3849 '
Windows (Command Prompt)
netstat -ano | findstr :3849
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 3849 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 3849
From Windows
Test-NetConnection HOST -Port 3849
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 3849

Block port 3849 in the firewall

ufw
sudo ufw deny 3849/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 3849 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 3849 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 3849' -Direction Inbound -Protocol TCP -LocalPort 3849 -Action Block
ufw
sudo ufw deny 3849/udp
iptables
sudo iptables -A INPUT -p udp --dport 3849 -j DROP
nftables
sudo nft add rule inet filter input udp dport 3849 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 3849' -Direction Inbound -Protocol UDP -LocalPort 3849 -Action Block

Related ports

3847msfw-control3848item3850qtms-bootstrap3851spectraport

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