By default, Healthcare Blocks servers will drop an idle SSH connection after 5 minutes. This setting is based on Center of Internet Security (CIS) Benchmarks, which are often cited during security assessments. To keep your SSH session alive, you can configure your local SSH client to send a packet to the server every x seconds, as described in this article.
Mac / Linux
In your ~/.ssh/config, add the following line to automatically send an SSH packet to the server every 30 seconds.
The above setting applies globally to every server you connect to via SSH. If you'd like to restrict the setting to a specific host, do this:
Host some-subdomain.healthcareblocks.com ServerAliveInterval 30
Note: wildcard settings (*.domain.com) also work with recent versions of SSH.
If you are using Git for Windows (Bash), the above procedure also applies.
If you are using PuTTY, you'll need to enable a setting named "Enable TCP keepalives" and enter a value of 30 for "Seconds between keepalives."