- Require TLS and authenticated submission.
- Make sure the server is not an open relay.
- Publish SPF, DKIM and DMARC for the domain.
Port 30939: Persistent peer-to-peer connections for block propagation, transaction relay, and BFT consensus message exchange.
Port 30939 is assigned by IANA to dilithium3 (Persistent peer-to-peer connections for block propagation, transaction relay, and BFT consensus message exchange.).
30939
How dilithium3 works
EmailMail servers hand messages to each other over port 30939, 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 30939 dangerous?
We have no specific security note for port 30939. Its risk depends on the program actually listening on it. General advice for email services:
IANA registry entries for port 30939
| Service | Port | Transport | Description | Reference | Updated |
|---|---|---|---|---|---|
| dilithium3 | 30939 | TCP, UDP | Persistent peer-to-peer connections for block propagation, transaction relay, and BFT consensus message exchange. | - | 2026-05-28 |
// source: IANA service name and port number registry
Which program uses port 30939, and is it reachable?
Linux
sudo ss -ltnup 'sport = :30939' # process listening on 30939
sudo lsof -nP -i :30939macOS
sudo lsof -nP -i :30939
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 30939 -State Listen | Select LocalAddress, OwningProcess Get-NetUDPEndpoint -LocalPort 30939 netstat -ano | findstr :30939
From another machine
nmap -p 30939 -sV <host> sudo nmap -sU -p 30939 <host> nc -zv <host> 30939
Block it in the firewall
sudo ufw deny 30939/tcp # Linux (ufw) New-NetFirewallRule -DisplayName "Block 30939" -Direction Inbound -LocalPort 30939 -Protocol TCP -Action Block # Windows
What is port 30939 used for?
Port 30939 is assigned by IANA to dilithium3 (Persistent peer-to-peer connections for block propagation, transaction relay, and BFT consensus message exchange.).
Is port 30939 TCP or UDP?
Port 30939 is registered for TCP and UDP.
Is it safe to open port 30939?
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 30939 is open?
On Linux run "ss -ltnup 'sport = :30939'", on macOS "lsof -nP -i :30939", and on Windows "netstat -ano | findstr :30939" to see the local process. From another machine, "nmap -p 30939 <host>" shows whether it is reachable.