"Failed to connect to host at <mail.server.hostname.or.IP> Unable to secure socket:-1."

Products

• ISG Proxy
• ProxySG Software - SGOS

Issue/Introduction

Proxy fails to upload event logs over SMTP Secure (SMTPS).  Test SMTP is failing with an error "Failed to connect to host at <mail.server.hostname.or.IP> Unable to secure socket:-1."

Environment

Proxy is configured to upload event logs using SMTP protocol, with SSL Device Profile enabled.

Cause

- SMTP server certificate should be signed by the Root CA certificate trusted by the ProxySG.

- With SSL device profile enabled, proxy is using Implicit TLS mode. Proxy is establishing TLS handshake immediately, without STARTTLS message.

Resolution

1. Allow the network communication between ProxySG and SMTP server over the configured port.

2. Make sure Root CA certificate and intermediate CA certificates used to sign SMTP certificate are imported to the ProxySG certificate store. Steps are in the KB. 

3. Enable Implicit TLS mode in the Mail server.

Additional Information

While checking packet capture using Wireshark, disable SMTP protocol (GUI -> Analyze -> Enabled Protocols) to see the TLS handshake. This is applicable while port 587 is used.