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Port 1025 (blackjack)

IANA assigns port 1025 to blackjack: network blackjack.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
blackjack TCP network blackjack - -
blackjack UDP network blackjack - -

Check what is listening on port 1025

Linux: is anything listening on TCP 1025?
sudo ss -tlnp 'sport = :1025'
Linux: UDP 1025
sudo ss -ulnp 'sport = :1025'
Linux / macOS: which process owns the port
sudo lsof -nP -i :1025
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':1025 '
Windows (Command Prompt)
netstat -ano | findstr :1025
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 1025 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 1025
From Windows
Test-NetConnection HOST -Port 1025
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 1025

Block port 1025 in the firewall

ufw
sudo ufw deny 1025/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 1025 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 1025 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 1025' -Direction Inbound -Protocol TCP -LocalPort 1025 -Action Block
ufw
sudo ufw deny 1025/udp
iptables
sudo iptables -A INPUT -p udp --dport 1025 -j DROP
nftables
sudo nft add rule inet filter input udp dport 1025 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 1025' -Direction Inbound -Protocol UDP -LocalPort 1025 -Action Block

Related ports

1021exp11022exp21026cap10276a44

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