GetAgentSocketFromConfig computes SSH authentication agent socket path using default ssh config's IdentityAgent and ForwardAgent keywords.

GetDefaultAgentSocket returns default ssh authentication agent socket (read from SSH_AUTH_SOCK env).

GetLogin tries to get sudo user from env, falling back to current user.

GetPrivateKeysFromConfig tries to extract PrivateKeys from default config's IdentityFiles specified for provided host.

GetUsernameFromConfig extracts User keyword value for given host from default ssh config.