- Require TLS and authenticated submission.
- Make sure the server is not an open relay.
- Publish SPF, DKIM and DMARC for the domain.
Port 854: Dynamic Link Exchange Protocol (DLEP)
Port 854 is assigned by IANA to dlep (Dynamic Link Exchange Protocol (DLEP)).
854
How dlep works
EmailMail servers hand messages to each other over port 854, 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
- Well-known (0-1023)
- Category
Is port 854 dangerous?
We have no specific security note for port 854. Its risk depends on the program actually listening on it. General advice for email services:
IANA registry entries for port 854
| Service | Port | Transport | Description | Reference | Updated |
|---|---|---|---|---|---|
| dlep | 854 | TCP, UDP | Dynamic Link Exchange Protocol (DLEP) | RFC 8175 | 2017-04-03 |
// source: IANA service name and port number registry
Which program uses port 854, and is it reachable?
Linux
sudo ss -ltnup 'sport = :854' # process listening on 854
sudo lsof -nP -i :854macOS
sudo lsof -nP -i :854
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 854 -State Listen | Select LocalAddress, OwningProcess Get-NetUDPEndpoint -LocalPort 854 netstat -ano | findstr :854
From another machine
nmap -p 854 -sV <host> sudo nmap -sU -p 854 <host> nc -zv <host> 854
Block it in the firewall
sudo ufw deny 854/tcp # Linux (ufw) New-NetFirewallRule -DisplayName "Block 854" -Direction Inbound -LocalPort 854 -Protocol TCP -Action Block # Windows
What is port 854 used for?
Port 854 is assigned by IANA to dlep (Dynamic Link Exchange Protocol (DLEP)).
Is port 854 TCP or UDP?
Port 854 is registered for TCP and UDP.
Is it safe to open port 854?
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 854 is open?
On Linux run "ss -ltnup 'sport = :854'", on macOS "lsof -nP -i :854", and on Windows "netstat -ano | findstr :854" to see the local process. From another machine, "nmap -p 854 <host>" shows whether it is reachable.