ec2: connection fails on older versions of OpenSSH.

[Hweinstock]

Problem

• Connection (remove-window) fails when OpenSSH < 7.6
• Logs from Amazon Linux 2 machine:

OpenSSH_7.4p1, OpenSSL 1.0.2k-fips  26 Jan 2017
debug1: Reading configuration data /home/hkobew/.ssh/config
debug1: Reading configuration data /home/hkobew/.ssh/bastions-config
/home/hkobew/.ssh/config line 7: unsupported option "accept-new".

• Looks like accept-new option for StrictHostKeyChecking is not yet supported in this version: https://serverfault.com/questions/1105812/command-line-line-0-unsupported-option-accept-new-how-to-fix-this

Steps to reproduce the issue

Attempt connection to any EC2 instance from an Amazon Linux Machine with OpenSSH < 7.6.

Expected behavior

System details (run AWS: About and/or Amazon Q: About)

• OS: Amazon Linux 2
• Visual Studio Code version: 1.85
• AWS Toolkit version: 1.85
• Amazon Q version: 3.33.0
• OpenSSH 7.4

[Hweinstock]

There are two straightforward workarounds.

1. Manually edit ~/.ssh/config such that StrictHostKeyChecking: no or StrictHostKeyChecking: ask (not preferred).
2. Update OpenSSH to 7.6+. On amazon linux this can be done via https://gist.github.com/roommen/18cd78d07b0fbc962de4e79c1d468f92

Relevant Links:
ssh config docs: https://linux.die.net/man/5/ssh_config
OpenSSH docs: https://linux.die.net/man/1/ssh