- Keep directory and authentication services on internal networks.
- Require signing or TLS and disable anonymous queries.
- Monitor authentication failures for spraying and brute force.
Port 5635: SFM Authentication Subsystem
Port 5635 is assigned by IANA to sfmsso (SFM Authentication Subsystem).
5635
How sfmsso works
Directory & authenticationThe client proves who it is on port 5635 and gets an answer (or a ticket) it can use with other services.
- 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
- Directory & authentication
Is port 5635 dangerous?
We have no specific security note for port 5635. Its risk depends on the program actually listening on it. General advice for directory & authentication services:
IANA registry entries for port 5635
| Service | Port | Transport | Description | Reference | Updated |
|---|---|---|---|---|---|
| sfmsso | 5635 | TCP | SFM Authentication Subsystem | - | 2008-09-15 |
| - | 5635 | - | Reserved | - | - |
// source: IANA service name and port number registry
Which program uses port 5635, and is it reachable?
Linux
sudo ss -ltnup 'sport = :5635' # process listening on 5635
sudo lsof -nP -i :5635macOS
sudo lsof -nP -i :5635
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 5635 -State Listen | Select LocalAddress, OwningProcess Get-NetUDPEndpoint -LocalPort 5635 netstat -ano | findstr :5635
From another machine
nmap -p 5635 -sV <host> nc -zv <host> 5635
Block it in the firewall
sudo ufw deny 5635/tcp # Linux (ufw) New-NetFirewallRule -DisplayName "Block 5635" -Direction Inbound -LocalPort 5635 -Protocol TCP -Action Block # Windows
What is port 5635 used for?
Port 5635 is assigned by IANA to sfmsso (SFM Authentication Subsystem).
Is port 5635 TCP or UDP?
Port 5635 is registered for TCP.
Is it safe to open port 5635?
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. Keep directory and authentication services on internal networks.
How do I check if port 5635 is open?
On Linux run "ss -ltnup 'sport = :5635'", on macOS "lsof -nP -i :5635", and on Windows "netstat -ano | findstr :5635" to see the local process. From another machine, "nmap -p 5635 <host>" shows whether it is reachable.
Other directory & authentication ports
:389 LDAP tcp · udp · high risk :636 LDAPS tcp · udp · moderate risk :88 Kerberos tcp · udp · high risk :3268 Global Catalog (LDAP) tcp · udp · high risk :1812 RADIUS udp · tcp · moderate risk :31 MSG Authentication tcp · udp :49 Login Host Protocol (TACACS) tcp · udp :56 XNS Authentication tcp · udp