Cannot ssh into ISOBlue with good connectivity

[wang701]

Both @aultac and I have seen this problem (although we have only seen it with ISOBlue HD but I hope we can replicate that on ISOBlue 2.0).

Description

• LED4 (network connectivity LED) on ISOBlue is green (meaning it has Internet).
• ssh-forward.service on ISOBlue is running fine (no error or anything by using systemctl status ssh-forward)

However, when you try to ssh into the device on vip4, it fails.

Files

ISOBlue

• /lib/systemd/system/ssh-forward.service
• /lib/systemd/system/heartbeat.service
• /etc/ssh/sshd_config

vip4

• /etc/ssh/sshd_config

To Reproduce

I don't know the exact steps to reproduce this but this issue does show up quite often when the LTE connectivity is intermittent.

Tasks

Note that heartbeat.service which runs heartbeat updates the color of LED4 once per minute. For LED4, it is possible that within the one minute interval, the intermittent Internet connectivity is not reflected in the color of the LED. I also suspect that when the Internet is intermittent, ssh forward breaks and neither an ISOBlue or vip4 is set up right in terms of ssh configurations to counter that.

• Simulate intermittent network connectivity and observe the statuses of LED and ssh-forward.service.
• Adjust ssh configurations for the case that ssh forward breaks when Internet goes out.