enhance: Expose a listen interface

[LaurenceJJones]

newt/authdaemon/server.go

Lines 24 to 33 in b6f13a1

	type Config struct {
	// DisableHTTPS: when true, Run() does not start the HTTPS server (for embedded use inside Newt). Call ProcessConnection directly for connection events.
	DisableHTTPS bool
	Port int // Required when DisableHTTPS is false. Listen port for the HTTPS server. No default.
	PresharedKey string // Required when DisableHTTPS is false. HTTP auth (Authorization: Bearer <key> or X-Preshared-Key: <key>). No default.
	CACertPath string // Required. Where to write the CA cert (e.g. /etc/ssh/ca.pem). No default.
	Force bool // If true, overwrite existing CA cert (and other items) when content differs. Default false.
	PrincipalsFilePath string // Required. Path to the principals data file (JSON: username -> array of principals). No default.
	GenerateRandomPassword bool // If true, set a random password on users when they are provisioned (for SSH PermitEmptyPasswords no).
	}

Currently we only expose a port option but setups where you dont want to bind to all interfaces it would be useful to allow listen or the base of the addr for a specific interface.

then

newt/authdaemon/server.go

Line 126 in b6f13a1

s.addr = fmt.Sprintf(":%d", cfg.Port)

can be something like

s.addr = fmt.Sprintf("%s:%d", cfg.Listen, cfg.Port)

if listen is empty string then we still get the bind to all interfaces :port

brain dump maybe bind is better terminology.

[LaurenceJJones]

related too #287