IgnoreUnknown AddKeysToAgent,UseKeychain

Host github.com
  AddKeysToAgent yes
  IgnoreUnknown UseKeychain
  UseKeychain yes
  IdentityFile ~/.ssh/github_rsa
  HostName github.com

Host *
  AddKeysToAgent yes
  IgnoreUnknown UseKeychain
  UseKeychain yes
  IdentityFile ~/.ssh/id_rsa