- Require TLS and authenticated submission.
- Make sure the server is not an open relay.
- Publish SPF, DKIM and DMARC for the domain.
Port 35356: Gutters Note Exchange
Port 35356 is assigned by IANA to guttersnex (Gutters Note Exchange).
35356
How guttersnex works
EmailMail servers hand messages to each other over port 35356, one hop at a time, until the recipient's server.
- Transport
- TCP
- 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 35356 dangerous?
We have no specific security note for port 35356. Its risk depends on the program actually listening on it. General advice for email services:
IANA registry entries for port 35356
| Service | Port | Transport | Description | Reference | Updated |
|---|---|---|---|---|---|
| guttersnex | 35356 | TCP | Gutters Note Exchange | - | 2011-07-19 |
| - | 35356 | - | Reserved | - | - |
// source: IANA service name and port number registry
Which program uses port 35356, and is it reachable?
Linux
sudo ss -ltnup 'sport = :35356' # process listening on 35356
sudo lsof -nP -i :35356macOS
sudo lsof -nP -i :35356
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 35356 -State Listen | Select LocalAddress, OwningProcess Get-NetUDPEndpoint -LocalPort 35356 netstat -ano | findstr :35356
From another machine
nmap -p 35356 -sV <host> nc -zv <host> 35356
Block it in the firewall
sudo ufw deny 35356/tcp # Linux (ufw) New-NetFirewallRule -DisplayName "Block 35356" -Direction Inbound -LocalPort 35356 -Protocol TCP -Action Block # Windows
What is port 35356 used for?
Port 35356 is assigned by IANA to guttersnex (Gutters Note Exchange).
Is port 35356 TCP or UDP?
Port 35356 is registered for TCP.
Is it safe to open port 35356?
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 35356 is open?
On Linux run "ss -ltnup 'sport = :35356'", on macOS "lsof -nP -i :35356", and on Windows "netstat -ano | findstr :35356" to see the local process. From another machine, "nmap -p 35356 <host>" shows whether it is reachable.