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Port 3421 (bmap)

IANA assigns port 3421 to bmap: Bull Apprise portmapper.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
bmap TCP Bull Apprise portmapper Jeremy Gilbert -
bmap UDP Bull Apprise portmapper Jeremy Gilbert -

Check what is listening on port 3421

Linux: is anything listening on TCP 3421?
sudo ss -tlnp 'sport = :3421'
Linux: UDP 3421
sudo ss -ulnp 'sport = :3421'
Linux / macOS: which process owns the port
sudo lsof -nP -i :3421
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':3421 '
Windows (Command Prompt)
netstat -ano | findstr :3421
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 3421 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 3421
From Windows
Test-NetConnection HOST -Port 3421
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 3421

Block port 3421 in the firewall

ufw
sudo ufw deny 3421/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 3421 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 3421 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 3421' -Direction Inbound -Protocol TCP -LocalPort 3421 -Action Block
ufw
sudo ufw deny 3421/udp
iptables
sudo iptables -A INPUT -p udp --dport 3421 -j DROP
nftables
sudo nft add rule inet filter input udp dport 3421 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 3421' -Direction Inbound -Protocol UDP -LocalPort 3421 -Action Block

Related ports

3419softaudit3420ifcp-port3422rusb-sys-port3423xtrm

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