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Port 25100 (db2c-tls)

IANA assigns port 25100 to db2c-tls: IBM Db2 Client Interface - Encrypted.

Registered (user) port, 1024-49151 TCP

IANA assignment

Service nameProtoDescriptionAssigneeReference
db2c-tls TCP IBM Db2 Client Interface - Encrypted IBM -

Registry dates for this port: registered 2024-03-05.

Check what is listening on port 25100

Linux: is anything listening on TCP 25100?
sudo ss -tlnp 'sport = :25100'
Linux / macOS: which process owns the port
sudo lsof -nP -i :25100
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':25100 '
Windows (Command Prompt)
netstat -ano | findstr :25100
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 25100 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 25100
From Windows
Test-NetConnection HOST -Port 25100

Block port 25100 in the firewall

ufw
sudo ufw deny 25100/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 25100 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 25100 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 25100' -Direction Inbound -Protocol TCP -LocalPort 25100 -Action Block

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