How can versions earlier that macOS Sierra ignore the .ssh_config UseKeychain option?

Question

I am sharing my ssh_config between a sierra macbook and machines with earlier versions, ie Yosemite. But when it reads UseKeychain yes, it considers it a missconfiguration.

Can this be fixed?

Answer 1

You can use Match blocks in the ssh_config to differentiate between OS versions, for example:

# or some other condition that is true only on your new systems
Match exec ssh -V | grep -v OpenSSH_6
  UseKeychain yes

Answer 2

You can use IgnoreUnknown:

IgnoreUnknown UseKeychain
UseKeychain yes

I found that information here: https://developer.apple.com/library/content/technotes/tn2449/_index.html