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Port 1051 (optima-vnet)

IANA assigns port 1051 to optima-vnet: Optima VNET.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
optima-vnet TCP Optima VNET Ralf Doewich -
optima-vnet UDP Optima VNET Ralf Doewich -

Check what is listening on port 1051

Linux: is anything listening on TCP 1051?
sudo ss -tlnp 'sport = :1051'
Linux: UDP 1051
sudo ss -ulnp 'sport = :1051'
Linux / macOS: which process owns the port
sudo lsof -nP -i :1051
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':1051 '
Windows (Command Prompt)
netstat -ano | findstr :1051
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 1051 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 1051
From Windows
Test-NetConnection HOST -Port 1051
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 1051

Block port 1051 in the firewall

ufw
sudo ufw deny 1051/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 1051 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 1051 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 1051' -Direction Inbound -Protocol TCP -LocalPort 1051 -Action Block
ufw
sudo ufw deny 1051/udp
iptables
sudo iptables -A INPUT -p udp --dport 1051 -j DROP
nftables
sudo nft add rule inet filter input udp dport 1051 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 1051' -Direction Inbound -Protocol UDP -LocalPort 1051 -Action Block

Related ports

1049td-postman1050cma1052ddt1053remote-as

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