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Port 20001 (microsan)

IANA assigns port 20001 to microsan: MicroSAN.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
microsan TCP MicroSAN Thomas E Ludwig -
microsan UDP MicroSAN Thomas E Ludwig -

Registry dates for this port: registered 2004-02.

Check what is listening on port 20001

Linux: is anything listening on TCP 20001?
sudo ss -tlnp 'sport = :20001'
Linux: UDP 20001
sudo ss -ulnp 'sport = :20001'
Linux / macOS: which process owns the port
sudo lsof -nP -i :20001
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':20001 '
Windows (Command Prompt)
netstat -ano | findstr :20001
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 20001 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 20001
From Windows
Test-NetConnection HOST -Port 20001
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 20001

Block port 20001 in the firewall

ufw
sudo ufw deny 20001/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 20001 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 20001 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 20001' -Direction Inbound -Protocol TCP -LocalPort 20001 -Action Block
ufw
sudo ufw deny 20001/udp
iptables
sudo iptables -A INPUT -p udp --dport 20001 -j DROP
nftables
sudo nft add rule inet filter input udp dport 20001 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 20001' -Direction Inbound -Protocol UDP -LocalPort 20001 -Action Block

Related ports

19999dnp-sec20000DNP320002commtact-http20003commtact-https

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