- Require TLS and authenticated submission.
- Make sure the server is not an open relay.
- Publish SPF, DKIM and DMARC for the domain.
Port 3667: IBM Information Exchange
Port 3667 is assigned by IANA to infoexch (IBM Information Exchange).
3667
How infoexch works
EmailMail servers hand messages to each other over port 3667, 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 3667 dangerous?
We have no specific security note for port 3667. Its risk depends on the program actually listening on it. General advice for email services:
IANA registry entries for port 3667
| Service | Port | Transport | Description | Reference | Updated |
|---|---|---|---|---|---|
| infoexch | 3667 | TCP, UDP | IBM Information Exchange | - | 2003-01 |
// source: IANA service name and port number registry
Which program uses port 3667, and is it reachable?
Linux
sudo ss -ltnup 'sport = :3667' # process listening on 3667
sudo lsof -nP -i :3667macOS
sudo lsof -nP -i :3667
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 3667 -State Listen | Select LocalAddress, OwningProcess Get-NetUDPEndpoint -LocalPort 3667 netstat -ano | findstr :3667
From another machine
nmap -p 3667 -sV <host> sudo nmap -sU -p 3667 <host> nc -zv <host> 3667
Block it in the firewall
sudo ufw deny 3667/tcp # Linux (ufw) New-NetFirewallRule -DisplayName "Block 3667" -Direction Inbound -LocalPort 3667 -Protocol TCP -Action Block # Windows
What is port 3667 used for?
Port 3667 is assigned by IANA to infoexch (IBM Information Exchange).
Is port 3667 TCP or UDP?
Port 3667 is registered for TCP and UDP.
Is it safe to open port 3667?
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 3667 is open?
On Linux run "ss -ltnup 'sport = :3667'", on macOS "lsof -nP -i :3667", and on Windows "netstat -ano | findstr :3667" to see the local process. From another machine, "nmap -p 3667 <host>" shows whether it is reachable.