Connection refused with implicit tls proftpd on Azure VM - azure

Question

We have a proftpd server on an AzureVM configured to use implicit ftps.
Error:
Status: Connecting to myPublicIP:990...
Status: Connection attempt failed with "ECONNREFUSED - Connection refused by > server".
Error: Could not connect to server
Relevant configuration
# /etc/proftpd/proftpd.conf
Port 21
PassivePorts 49152 49190
MasqueradeAddress myPublicIP
# /etc/proftpd/tls.conf
TLSEngine on
TLSLog /var/log/proftpd/tls.log
TLSProtocol TLSv1 TLSv1.2
TLSCipherSuite AES128+EECDH:AES128+EDH
#TLSOptions NoCertRequest AllowClientRenegotiations UseImplicitSSL EnableDiags
TLSRSACertificateFile /etc/proftpd/ssl/certificate.pem
TLSRSACertificateKeyFile /etc/proftpd/ssl/certificate.key
TLSVerifyClient off
TLSRequired on
I have open the following ports in the security group and interface of the virtual machine:
20,21,49152-49190,990,989.
If I do not force the connection through the implicit port, the rest of the connections works perfectly

Answer 1

According to your configuration, you did not enable implicit. If you execute netstat -ant|grep 990, it should return null.
So, if you use port to connect ftp server, you will get the error log.
You could check this link to enable implicit.
<IfModule mod_tls.c>
<VirtualHost 0.0.0.0>
Port 990
TLSEngine on
TLSOptions UseImplicitSSL
</VirtualHost>
</IfModule>
Then you need restart ftp server, service xinetd restart
When you execute netstat -ant|grep 990, you will get like below:
root#shui:~# netstat -ant|grep 990
tcp6 0 0 :::990 :::* LISTEN