Behind a corporate proxy – Git

.gitconfig

[credential]
helper = manager
[url "https://"]
insteadOf = git:/
[url "https://github.com/"]
insteadOf = git@github.com:
[http]
proxy = http://username:password@xxx.xxx.xxx.xxx:xxxx
[https]
proxy = http://username:password@xxx.xxx.xxx.xxx:xxxx

If you are using macOS, change the credential from manager to osxkeychain.

[credential]
helper = osxkeychain