- Require TLS and authenticated submission.
- Make sure the server is not an open relay.
- Publish SPF, DKIM and DMARC for the domain.
Port 12000: IBM Enterprise Extender SNA XID Exchange
Port 12000 is assigned by IANA to entextxid (IBM Enterprise Extender SNA XID Exchange).
12000
How entextxid works
EmailMail servers hand messages to each other over port 12000, one hop at a time, until the recipient's server.
- Transport
- TCP · UDP
- Exposure risk
- not rated depends on the program listening
- Encryption
- Unknownnot stated by the registry
- IANA status
- Assigned1 registered service
- Range
- Registered (1024-49151)
- Category
Is port 12000 dangerous?
We have no specific security note for port 12000. Its risk depends on the program actually listening on it. General advice for email services:
IANA registry entries for port 12000
| Service | Port | Transport | Description | Reference | Updated |
|---|---|---|---|---|---|
| entextxid | 12000 | TCP, UDP | IBM Enterprise Extender SNA XID Exchange | - | - |
// source: IANA service name and port number registry
Which program uses port 12000, and is it reachable?
Linux
sudo ss -ltnup 'sport = :12000' # process listening on 12000
sudo lsof -nP -i :12000macOS
sudo lsof -nP -i :12000
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 12000 -State Listen | Select LocalAddress, OwningProcess Get-NetUDPEndpoint -LocalPort 12000 netstat -ano | findstr :12000
From another machine
nmap -p 12000 -sV <host> sudo nmap -sU -p 12000 <host> nc -zv <host> 12000
Block it in the firewall
sudo ufw deny 12000/tcp # Linux (ufw) New-NetFirewallRule -DisplayName "Block 12000" -Direction Inbound -LocalPort 12000 -Protocol TCP -Action Block # Windows
What is port 12000 used for?
Port 12000 is assigned by IANA to entextxid (IBM Enterprise Extender SNA XID Exchange).
Is port 12000 TCP or UDP?
Port 12000 is registered for TCP and UDP.
Is it safe to open port 12000?
It depends on the program that listens on it. Open it only for a service you know and only to the networks that need it. Require TLS and authenticated submission.
How do I check if port 12000 is open?
On Linux run "ss -ltnup 'sport = :12000'", on macOS "lsof -nP -i :12000", and on Windows "netstat -ano | findstr :12000" to see the local process. From another machine, "nmap -p 12000 <host>" shows whether it is reachable.