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Port 7421 (mtportmon)

IANA assigns port 7421 to mtportmon: Matisse Port Monitor.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
mtportmon TCP Matisse Port Monitor Didier Cabannes -
mtportmon UDP Matisse Port Monitor Didier Cabannes -

Registry dates for this port: registered 2004-11.

Check what is listening on port 7421

Linux: is anything listening on TCP 7421?
sudo ss -tlnp 'sport = :7421'
Linux: UDP 7421
sudo ss -ulnp 'sport = :7421'
Linux / macOS: which process owns the port
sudo lsof -nP -i :7421
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':7421 '
Windows (Command Prompt)
netstat -ano | findstr :7421
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 7421 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 7421
From Windows
Test-NetConnection HOST -Port 7421
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 7421

Block port 7421 in the firewall

ufw
sudo ufw deny 7421/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 7421 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 7421 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 7421' -Direction Inbound -Protocol TCP -LocalPort 7421 -Action Block
ufw
sudo ufw deny 7421/udp
iptables
sudo iptables -A INPUT -p udp --dport 7421 -j DROP
nftables
sudo nft add rule inet filter input udp dport 7421 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 7421' -Direction Inbound -Protocol UDP -LocalPort 7421 -Action Block

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Assignment data: IANA port number registry (public domain), retrieved 2026-11-10.