37

I want to specify host names with two different ports in the Windows hosts file.

Is there a way to do it? Or is it not allowed by Windows itself?

I have been wasting my time searching for the solution for the last 8 hours.

Is it possible to specify ports in the host file, hosts? E.g.: 127.0.0.1:80 and 127.0.0.1:9211

2
  • 2
    The HOSTS file only associates names with IP addresses, not IPs+port(s). Do check superuser.com, however, by describing more of the specifics of what you are trying to do (is this for a web server etc. etc.) as there are many ways to achieve this type of mapping, but always depending on specifics at hand.
    – mjv
    Feb 21, 2010 at 18:44
  • You need NGNIX or Apache HTTP server as a proxy server for forwarding http requests to appropriate application -> which listens particular port
    – Musa
    Feb 8, 2018 at 18:08

3 Answers 3

26

Simply use IP addresses without ports. Example:

192.168.2.50  example.com

Then, to access 192.168.2.50:5555 from your browser (or other program):

http://example.com:5555/

The hosts file can be found at:

Linux /etc/hosts

Windows: C:\Windows\System32\drivers\etc\hosts

3
  • It will be helpful to add both path and the name of the file to be edited. Sep 15, 2016 at 10:21
  • 1
    Can you possibly update with the reason for NOT specifying the port number when editing the file at C:\Windows\System32\drivers\etc\hosts ? Sep 15, 2016 at 19:57
  • 1
    That's covered in the other answers. Sep 15, 2016 at 21:35
19

You cannot associate a port number with a hostname mapped to an IP in the hosts file. You can achieve this with Fiddler though using FiddlerScript: 

if (oSession.HostnameIs("somesite.com")){
    oSession.bypassGateway = true;
    oSession["x-overrideHost"] = "1.2.3.4:8080";
}
2
  • 8
    Nice suggestion for tech users. Just to clarify, 1) First install Fiddler 2) Then open it and go to Rules Menu and pick Customize Rules option ( or press Ctrl + R on windows ). This will open a JS file in notepad. 3) Find static function OnBeforeRequest and paste the script suggested by @John inside its body. Also HostNameIs will not work, it should be HostnameIs. Hope this helps.
    – Riz
    Aug 13, 2013 at 7:40
  • Are you aware of any open source alternative (james, owasp zap, or other) which can be used to the same effect?
    – Marc.2377
    Dec 21, 2018 at 18:36
18
  • The hosts file is for resolving hostnames to IP addresses only
  • If you do not specify a port as part of a URL, e.g. <protocol>://<hostname>[:<port>][/path], your browser will use the default port for the protocol: HTTP/80, HTTPS/443, FTP/21

Example Problem Scenario

  1. Applications typically set their servers to the same default IP address 127.0.0.1 (aka localhost, defined in the hosts file).
  2. To allow routing traffic to the right server when multiple servers share the same IP, applications typically allow you to modify their port if needed, but not their IP address.
    • "if" you could change the servers IP address to another in the loopback reserved address space 127.0.0.0/8, then you probably wouldn't be attempting to set ports in the hosts file

Possible Solution

You can work around this using Windows' built-in networking tool netsh as a port proxy.


Overview

http://example.app
|                                 <--browser defaults to HTTP port 80
+-> http://example.app:80          
    |                             <--Hostname resolved to IP by Hosts File
    +-> http://127.65.43.21:80    
        |                         <--Link by netsh Utility
        +-> http://127.0.0.1:8081 

Actions

  1. Start your app's HTTP server on a custom port: localhost:8081
  2. Add a line in the hosts file that maps a free IP address to the app's hostname:
    • Example: 127.65.43.21 example.app
    • I suggested 127.65.43.21 but any free address in the subnet 127.0.0.0/8 can be used
    • Verify that 127.65.43.21:80 isn't already in use by another service. If it is, use a different IP. Check using: netstat -a -n -p TCP | FINDSTR "LISTENING"
  3. Add the following network configuration, using netsh:
netsh interface portproxy add v4tov4 listenport=80 listenaddress=127.65.43.21 connectport=8081 connectaddress=127.0.0.1
  1. Try to access the server at http://example.app

Notes:

  • These commands/file modifications need to be executed with Admin rights
  • netsh portproxy needs IPv6 libraries, even just to use v4tov4. Typically, these will be installed by default, otherwise, install them with netsh interface ipv6 install

You can see the entry you have added with the command:

netsh interface portproxy show v4tov4

You can remove the entry with the following command:

netsh interface portproxy delete v4tov4 listenport=80 listenaddress=127.65.43.21

Links to Resources:

Note: this answer is a duplication of my answer discussed in this similar question/answer on stackoverflow.

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