Explicit set the hostname

middleman-core/lib/middleman-core/application.rb

@@ -71,6 +71,10 @@ module Middleman
     # @return [Fixnum]
     config.define_setting :port, 4567, 'The preview server port'
 
+    # Which server name should be used
+    # @return [NilClass, String]
+    config.define_setting :host, nil , 'The preview host name'
+
     # Whether to serve the preview server over HTTPS.
     # @return [Boolean]
     config.define_setting :https, false, 'Serve the preview server over SSL/TLS'

middleman-core/lib/middleman-core/cli/server.rb

@@ -14,6 +14,9 @@ module Middleman::Cli
     method_option :port,
                   aliases: '-p',
                   desc: 'The port Middleman will listen on'
+    method_option :host,
+                  aliases: '-h',
+                  desc: 'The host name Middleman will use'
     method_option :https,
                   type: :boolean,
                   desc: 'Serve the preview server over SSL/TLS'
@@ -66,6 +69,7 @@ module Middleman::Cli
       params = {
         port: options['port'],
         https: options['https'],
+        host: options['host'],
         ssl_certificate: options['ssl_certificate'],
         ssl_private_key: options['ssl_private_key'],
         environment: options['environment'],

middleman-core/lib/middleman-core/preview_server.rb

@@ -112,12 +112,13 @@ module Middleman
 
           config[:environment] = opts[:environment].to_sym if opts[:environment]
           config[:port] = opts[:port] if opts[:port]
+          config[:host] = opts[:host].presence || Socket.gethostname.tr(' ', '+')
           config[:https] = opts[:https] unless opts[:https].nil?
           config[:ssl_certificate] = opts[:ssl_certificate] if opts[:ssl_certificate]
           config[:ssl_private_key] = opts[:ssl_private_key] if opts[:ssl_private_key]
         end
 
-        @host = Socket.gethostname.tr(' ', '+')
+        @host = @app.config[:host]
         @port = @app.config[:port]
         @https = @app.config[:https]
 
@@ -182,6 +183,7 @@ module Middleman
         http_opts = {
           Port: port,
           AccessLog: [],
+          ServerName: host,
           DoNotReverseLookup: true
         }