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Port 25900 (tasp-net)

IANA assigns port 25900 to tasp-net: TASP Network Comm.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
tasp-net TCP TASP Network Comm Martin Ellis -
tasp-net UDP TASP Network Comm Martin Ellis -

Registry dates for this port: registered 2004-11.

Check what is listening on port 25900

Linux: is anything listening on TCP 25900?
sudo ss -tlnp 'sport = :25900'
Linux: UDP 25900
sudo ss -ulnp 'sport = :25900'
Linux / macOS: which process owns the port
sudo lsof -nP -i :25900
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':25900 '
Windows (Command Prompt)
netstat -ano | findstr :25900
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 25900 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 25900
From Windows
Test-NetConnection HOST -Port 25900
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 25900

Block port 25900 in the firewall

ufw
sudo ufw deny 25900/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 25900 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 25900 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 25900' -Direction Inbound -Protocol TCP -LocalPort 25900 -Action Block
ufw
sudo ufw deny 25900/udp
iptables
sudo iptables -A INPUT -p udp --dport 25900 -j DROP
nftables
sudo nft add rule inet filter input udp dport 25900 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 25900' -Direction Inbound -Protocol UDP -LocalPort 25900 -Action Block

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