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Port 9990 (osm-appsrvr)

IANA assigns port 9990 to osm-appsrvr: OSM Applet Server.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
osm-appsrvr TCP OSM Applet Server Vinay Gupta -
osm-appsrvr UDP OSM Applet Server Vinay Gupta -

Registry dates for this port: registered 2003-08.

Check what is listening on port 9990

Linux: is anything listening on TCP 9990?
sudo ss -tlnp 'sport = :9990'
Linux: UDP 9990
sudo ss -ulnp 'sport = :9990'
Linux / macOS: which process owns the port
sudo lsof -nP -i :9990
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':9990 '
Windows (Command Prompt)
netstat -ano | findstr :9990
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 9990 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 9990
From Windows
Test-NetConnection HOST -Port 9990
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 9990

Block port 9990 in the firewall

ufw
sudo ufw deny 9990/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 9990 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 9990 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 9990' -Direction Inbound -Protocol TCP -LocalPort 9990 -Action Block
ufw
sudo ufw deny 9990/udp
iptables
sudo iptables -A INPUT -p udp --dport 9990 -j DROP
nftables
sudo nft add rule inet filter input udp dport 9990 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 9990' -Direction Inbound -Protocol UDP -LocalPort 9990 -Action Block

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