Error: Localhost:636 Connection Refused

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Note: This page applies to SFTP Gateway version 2.x. Visit Here for documentation on version 3.x.

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Overview

With SFTP Gateway, you may encounter the following error in the web admin UI:

localhost:636 Connection refused

The first troubleshooting step is to restart the LDAP service.

If the problem persists, follow along with the rest of this article to see if the VM is even listening on port 636.

Otherwise, email us at support@thorntech.com and we can help troubleshoot the issue.

Initial troubleshooting

SFTP Gateway uses LDAP behind the scenes. And LDAP runs on port 636.

If LDAP is down, the sftpgw-admin-api service will fail, and the web admin UI will give a red error message on the top right.

You can get the status of the LDAP service with the following commands:

sudo su
HOSTNAME=$(hostname | cut -d"." -f1)
systemctl status dirsrv@$HOSTNAME

Note: The commands above are just a fancy way of running systemctl status dirsrv@ip-172-31-4-199, or whatever your Private IPv4 DNS hostname is (without the .ec2.internal domain suffix).

If LDAP is down, you can restart it:

systemctl restart dirsrv@$HOSTNAME

At this point, you can refresh your web admin UI browser. If it's working, then you have solved the problem.

Diagnosing the issue further

If the LDAP service is active, but you're still seeing the localhost:636 error, then keep reading.

The LDAP service runs on two different ports:

• 389: This is normally used for clear text LDAP. But you can also run start_tls, which is TLS over 389. This is what we use for the ldapsearch CLI, which depends on nslcd.
• 636: This is the LDAP service used by Java.

To determine which ports are running on your VM, run this command:

netstat -ltnp

You should see the following output on a healthy VM:

Proto Recv-Q Send-Q Local Address           Foreign Address         State       PID/Program name    
tcp6       0      0 :::636                  :::*                    LISTEN      2571/ns-slapd       
tcp6       0      0 :::389                  :::*                    LISTEN      2571/ns-slapd 

And you should see the following output on a VM that didn't get to finish its initial configuration:

Proto Recv-Q Send-Q Local Address           Foreign Address         State       PID/Program name    
tcp6       0      0 :::389                  :::*                    LISTEN      2571/ns-slapd 

If you see the latter, please email us at support@thorntech.com. This may be the result of running an underpowered EC2 instance (we recommend a t3.medium or better), and the first time initialization did not have enough memory to complete.