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Port 7901 (tnos-sp)

IANA assigns port 7901 to tnos-sp: TNOS Service Protocol.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
tnos-sp TCP TNOS Service Protocol Rene Kurt -
tnos-sp UDP TNOS Service Protocol Rene Kurt -

Registry dates for this port: registered 2005-08.

Check what is listening on port 7901

Linux: is anything listening on TCP 7901?
sudo ss -tlnp 'sport = :7901'
Linux: UDP 7901
sudo ss -ulnp 'sport = :7901'
Linux / macOS: which process owns the port
sudo lsof -nP -i :7901
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':7901 '
Windows (Command Prompt)
netstat -ano | findstr :7901
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 7901 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 7901
From Windows
Test-NetConnection HOST -Port 7901
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 7901

Block port 7901 in the firewall

ufw
sudo ufw deny 7901/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 7901 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 7901 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 7901' -Direction Inbound -Protocol TCP -LocalPort 7901 -Action Block
ufw
sudo ufw deny 7901/udp
iptables
sudo iptables -A INPUT -p udp --dport 7901 -j DROP
nftables
sudo nft add rule inet filter input udp dport 7901 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 7901' -Direction Inbound -Protocol UDP -LocalPort 7901 -Action Block

Related ports

7887ubroker7900mevent7902tnos-dp7903tnos-dps

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