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      How to Set Up Squid Proxy for Private Connections on Ubuntu 20.04


      Introduction

      Proxy servers are a type of server application that functions as a gateway between an end user and an internet resource. Through a proxy server, an end user is able to control and monitor their web traffic for a wide variety of purposes, including privacy, security, and caching. For example, you can use a proxy server to make web requests from a different IP address than your own. You can also use a proxy server to research how the web is served differently from one jurisdiction to the next, or avoid some methods of surveillance or web traffic throttling.

      Squid is a stable, popular, open-source HTTP proxy. In this tutorial, you will be installing and configuring Squid to provide an HTTP proxy on a Ubuntu 20.04 server.

      Prerequisites

      To complete this guide, you will need:

      You will use the domain name your_domain in this tutorial, but you should substitute this with your own domain name, or IP address.

      Step 1 — Installing Squid Proxy

      Squid has many use cases beyond routing an individual user’s outbound traffic. In the context of large-scale server deployments, it can be used as a distributed caching mechanism, a load balancer, or another component of a routing stack. However, some methods of horizontally scaling server traffic that would typically have involved a proxy server have been surpassed in popularity by containerization frameworks such as Kubernetes, which distribute more components of an application. At the same time, using proxy servers to redirect web requests as an individual user has become increasingly popular for protecting your privacy. This is helpful to keep in mind when working with open-source proxy servers which may appear to have many dozens of features in a lower-priority maintenance mode. The use cases for a proxy have changed over time, but the fundamental technology has not.

      Begin by running the following commands as a non-root user to update your package listings and install Squid Proxy:

      • sudo apt update
      • sudo apt install squid

      Squid will automatically set up a background service and start after being installed. You can check that the service is running properly:

      • systemctl status squid.service

      Output

      ● squid.service - Squid Web Proxy Server Loaded: loaded (/lib/systemd/system/squid.service; enabled; vendor preset: enabled) Active: active (running) since Wed 2021-12-15 21:45:15 UTC; 2min 11s ago

      By default, Squid does not allow any clients to connect to it from outside of this server. In order to enable that, you’ll need to make some changes to its configuration file, which is stored in /etc/squid/squid.conf. Open it in nano or your favorite text editor:

      • sudo nano /etc/squid/squid.conf

      Be advised that Squid’s default configuration file is very, very long, and contains a massive number of options that have been temporarily disabled by putting a # at the start of the line they’re on, also called being commented out. You will most likely want to search through the file to find the lines you want to edit. In nano, this is done by pressing Ctrl+W, entering your search term, pressing Enter, and then repeatedly pressing Alt+W to find the next instance of that term if needed.

      Begin by navigating to the line containing the phrase http_access deny all. You should see a block of text explaining Squid’s default access rules:

      /etc/squid/squid.conf

      . . . 
      #
      # INSERT YOUR OWN RULE(S) HERE TO ALLOW ACCESS FROM YOUR CLIENTS
      #
      include /etc/squid/conf.d/*
      # Example rule allowing access from your local networks.
      # Adapt localnet in the ACL section to list your (internal) IP networks
      # from where browsing should be allowed
      #http_access allow localnet
      http_access allow localhost
      
      # And finally deny all other access to this proxy
      http_access deny all
      . . . 
      

      From this, you can see the current behavior – localhost is allowed; other connections are not. Note that these rules are parsed sequentially, so it’s a good idea to keep the deny all rule at the bottom of this configuration block. You could change that rule to allow all, enabling anyone to connect to your proxy server, but you probably don’t want to do that. Instead, you can add a line above http_access allow localhost that includes your own IP address, like so:

      /etc/squid/squid.conf

      #
      # INSERT YOUR OWN RULE(S) HERE TO ALLOW ACCESS FROM YOUR CLIENTS
      #
      include /etc/squid/conf.d/*
      # Example rule allowing access from your local networks.
      acl localnet src your_ip_address
      # Adapt localnet in the ACL section to list your (internal) IP networks
      # from where browsing should be allowed
      #http_access allow localnet
      http_access allow localhost
      
      • acl means an Access Control List, a common term for permissions policies
      • localnet in this case is the name of your ACL.
      • src is where the request would originate from under this ACL, i.e., your IP address.

      If you don’t know your local IP address, it’s quickest to go to a site like What’s my IP which can tell you where you accessed it from. After making that change, save and close the file. If you are using nano, press Ctrl+X, and then when prompted, Y and then Enter.

      At this point, you could restart Squid and connect to it, but there’s more you can do in order to secure it first.

      Step 2 — Securing Squid

      Most proxies, and most client-side apps that connect to proxies (e.g., web browsers) support multiple methods of authentication. These can include shared keys, or separate authentication servers, but most commonly entail regular username-password pairs. Squid allows you to create username-password pairs using built-in Linux functionality, as an additional or an alternative step to restricting access to your proxy by IP address. To do that, you’ll create a file called /etc/squid/passwords and point Squid’s configuration to it.

      First, you’ll need to install some utilities from the Apache project in order to have access to a password generator that Squid likes.

      • sudo apt install apache2-utils

      This package provides the htpasswd command, which you can use in order to generate a password for a new Squid user. Squid’s usernames won’t overlap with system usernames in any way, so you can use the same name you’ve logged in with if you want. You’ll be prompted to add a password as well:

      • sudo htpasswd -c /etc/squid/passwords your_squid_username

      This will store your username along with a hash of your new password in /etc/squid/passwords, which will be used as an authentication source by Squid. You can cat the file afterward to see what that looks like:

      • sudo cat /etc/squid/passwords

      Output

      sammy:$apr1$Dgl.Mtnd$vdqLYjBGdtoWA47w4q1Td.

      After verifying that your username and password have been stored, you can update Squid’s configuration to use your new /etc/squid/passwords file. Using nano or your favorite text editor, reopen the Squid configuration file and add the following highlighted lines:

      • sudo nano /etc/squid/squid.conf

      /etc/squid/squid.conf

      …
      #
      # INSERT YOUR OWN RULE(S) HERE TO ALLOW ACCESS FROM YOUR CLIENTS
      #
      include /etc/squid/conf.d/*
      auth_param basic program /usr/lib/squid3/basic_ncsa_auth /etc/squid/passwords
      auth_param basic realm proxy
      acl authenticated proxy_auth REQUIRED
      # Example rule allowing access from your local networks.
      acl localnet src your_ip_address
      # Adapt localnet in the ACL section to list your (internal) IP networks
      # from where browsing should be allowed
      #http_access allow localnet
      http_access allow localhost
      http_access allow authenticated
      # And finally deny all other access to this proxy
      http_access deny all
      …
      

      These additional directives tell Squid to check in your new passwords file for password hashes that can be parsed using the basic_ncsa_auth mechanism, and to require authentication for access to your proxy. You can review Squid’s documentation for more information on this or other authentication methods. After that, you can finally restart Squid with your configuration changes. This might take a moment to complete.

      • sudo systemctl restart squid.service

      And don’t forget to open port 3128 in your firewall if you’re using ufw:

      In the next step, you’ll connect to your proxy at last.

      Step 3 — Connecting through Squid

      In order to demonstrate your Squid server, you’ll use a command line program called curl, which is popular for making different types of web requests. In general, if you want to verify whether a given connection should be working in a browser under ideal circumstances, you should always test first with curl. You’ll be using curl on your local machine in order to do this – it’s installed by default on all modern Windows, Mac, and Linux environments, so you can open any local shell to run this command:

      • curl -v -x http://your_squid_username:your_squid_password@your_server_ip:3128 http://www.google.com/

      The -x argument passes a proxy server to curl, and in this case you’re using the http:// protocol this time, specifying your username and password to this server, and then connecting to a known-working website like google.com. If the command was successful, you should see the following output:

      Output

      * Trying 138.197.103.77... * TCP_NODELAY set * Connected to 138.197.103.77 (138.197.103.77) port 3128 (#0) * Proxy auth using Basic with user 'sammy' > GET http://www.google.com/ HTTP/1.1

      It is also possible to access https:// websites with your Squid proxy without making any further configuration changes. These make use of a separate proxy directive called CONNECT in order to preserve SSL between the client and the server:

      • curl -v -x http://your_squid_username:your_squid_password@your_server_ip:3128 https://www.google.com/

      Output

      * Trying 138.197.103.77... * TCP_NODELAY set * Connected to 138.197.103.77 (138.197.103.77) port 3128 (#0) * allocate connect buffer! * Establish HTTP proxy tunnel to www.google.com:443 * Proxy auth using Basic with user 'sammy' > CONNECT www.google.com:443 HTTP/1.1 > Host: www.google.com:443 > Proxy-Authorization: Basic c2FtbXk6c2FtbXk= > User-Agent: curl/7.55.1 > Proxy-Connection: Keep-Alive > < HTTP/1.1 200 Connection established < * Proxy replied OK to CONNECT request * CONNECT phase completed!

      The credentials that you used for curl should now work anywhere else you might want to use your new proxy server.

      Conclusion

      In this tutorial, you learned to deploy a popular, open-source API endpoint for proxying traffic with little to no overhead. Many applications have built-in proxy support (often at the OS level) going back decades, making this proxy stack highly reusable.

      Next, you may want to learn how to deploy Dante, a SOCKS proxy which can run alongside Squid for proxying different types of web traffic.

      Because one of the most common use cases for proxy servers is proxying traffic to and from different global regions, you may want to review how to use Ansible to automate server deployments next, in case you find yourself wanting to duplicate this configuration in other data centers.



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      How to Set Up Dante Proxy for Private Connections on Ubuntu 20.04


      Introduction

      Proxy servers are a type of server application that functions as a gateway between an end user and an internet resource. Through a proxy server, an end user is able to control and monitor their web traffic for a wide variety of purposes, including privacy, security, and caching. For example, you can use a proxy server to make web requests from a different IP address than your own. You can also use a proxy server to research how the web is served differently from one jurisdiction to the next, or avoid some methods of surveillance or web traffic throttling.

      Dante is a stable, popular, open-source SOCKS proxy. In this tutorial, you will be installing and configuring Dante to provide a SOCKS proxy on a Ubuntu 20.04 server.

      Prerequisites

      To complete this guide, you will need:

      You will use the domain name your_domain in this tutorial, but you should substitute this with your own domain name, or IP address.

      Step 1 — Installing Dante

      Dante is an open-source SOCKS proxy server. SOCKS is a less widely used protocol, but it is more efficient for some peer-to-peer applications, and is preferred over HTTP for some kinds of traffic. Begin by running the following commands as a non-root user to update your package listings and install Dante:

      • sudo apt update
      • sudo apt install dante-server

      Dante will also automatically set up a background service and start after being installed. However, it is designed to gracefully quit with an error message the first time it runs, because it ships with all of its features disabled. You can verify this by using the systemctl command:

      • systemctl status danted.service

      Output

      ● danted.service - SOCKS (v4 and v5) proxy daemon (danted) Loaded: loaded (/lib/systemd/system/danted.service; enabled; vendor preset: enabled) Active: failed (Result: exit-code) since Wed 2021-12-15 21:48:22 UTC; 1min 45s ago Docs: man:danted(8) man:danted.conf(5) Main PID: 14496 (code=exited, status=1/FAILURE) Dec 15 21:48:21 proxies systemd[1]: Starting SOCKS (v4 and v5) proxy daemon (danted)... Dec 15 21:48:22 proxies systemd[1]: Started SOCKS (v4 and v5) proxy daemon (danted). Dec 15 21:48:22 proxies danted[14496]: Dec 15 21:48:22 (1639604902.102601) danted[14496]: warning: checkconfig(): no socks authentication methods enabled. This means all socks requests will be blocked after negotiation. Perhaps this is not intended?

      To successfully start Dante’s services, you’ll need to enable them in the config file.

      Dante’s config file is provided, by default, in /etc/danted.conf. If you open this file using nano or your favorite text editor, you will see a long list of configuration options, all of them disabled. You could try to navigate through this file and enable some options line-by-line, but in practice it will be more efficient and more readable to delete this file and replace it from scratch. Don’t worry about doing this. You can always review Dante’s default configuration by navigating to its online manual, and you could even redownload the package manually from Ubuntu’s package listing to reobtain the stock configuration file if you ever wanted. In the meantime, go ahead and delete it:

      Now you can replace it with something more concise. Opening a file with a text editor will automatically create the file if it doesn’t exist, so by using nano or your favorite text editor, you should now get an empty configuration file:

      • sudo nano /etc/danted.conf

      Add the following contents:

      /etc/danted.conf

      logoutput: syslog
      user.privileged: root
      user.unprivileged: nobody
      
      # The listening network interface or address.
      internal: 0.0.0.0 port=1080
      
      # The proxying network interface or address.
      external: eth0
      
      # socks-rules determine what is proxied through the external interface.
      socksmethod: username
      
      # client-rules determine who can connect to the internal interface.
      clientmethod: none
      
      client pass {
          from: 0.0.0.0/0 to: 0.0.0.0/0
      }
      
      socks pass {
          from: 0.0.0.0/0 to: 0.0.0.0/0
      }
      

      You now have a usable SOCKS server configuration, running on port 1080, which is a common convention for SOCKS. You can also break down the rest of this configuration file line-by-line:

      • logoutput refers to how Dante will log connections, in this case using regular system logging
      • user.privileged allows dante to have root permissions for checking permissions
      • user.unprivileged does not grant the server any permissions for running as an unprivileged user, as this is unnecessary when not granting more granular permissions
      • internal connection details specify the port that the service is running on and which IP addresses can connect
      • external connection details specify the network interface used for outbound connections, eth0 by default on most servers

      The rest of the configuration details deal with authentication methods, which are discussed in the next section. Don’t forget to open port 1080 in your firewall if you’re using ufw:

      At this point, you could restart Dante and connect to it, but you would have a SOCKS server that’s open to the entire world, which you probably don’t want, so you’ll learn how to secure it first.

      Step 2 — Securing Dante

      If you followed this tutorial so far, Dante will be making use of regular Linux user accounts for authentication. This is helpful, but the password used for that connection will be sent over plain text, so it’s important to create a dedicated SOCKS user that won’t have any other login privileges. To do that, you’ll use useradd with flags that won’t assign a login shell to the user, then set a password:

      • sudo useradd -r -s /bin/false your_dante_user
      • sudo passwd your_dante_user

      You’ll also want to avoid logging into this account over an unsecured wireless connection or sharing the server too widely. Otherwise, malicious actors can and will make repeated efforts to log in.

      Dante supports other authentication methods, but many clients (i.e., applications) that will connect to SOCKS proxies only support basic username and password authentication, so you may want to leave that part as-is. What you can do as an alternative is to restrict access to only specific IP addresses. This isn’t the most sophisticated option, but given the combination of technologies in use here, it’s a sensible one. You may have already learned how to restrict access to specific IP addresses with ufw from our prerequisite tutorials , but you can also do it within Dante directly. Edit your /etc/danted.conf:

      • sudo nano /etc/danted.conf

      /etc/danted.conf

      …
      client pass {
          from: your_ip_address/0 to: 0.0.0.0/0
      }
      

      In order to support multiple IP addresses, you can use CIDR notation, or just add another client pass {} configuration block:

      /etc/danted.conf

      client pass {
          from: your_ip_address/0 to: 0.0.0.0/0
      }
      
      client pass {
          from: another_ip_address/0 to: 0.0.0.0/0
      }
      

      After that, you can finally restart Dante with your configuration changes.

      • sudo systemctl restart danted.service

      This time, when you check the service status, you should see it running without any errors:

      • systemctl status danted.service

      Output

      ● danted.service - SOCKS (v4 and v5) proxy daemon (danted) Loaded: loaded (/lib/systemd/system/danted.service; enabled; vendor preset: enable> Active: active (running) since Thu 2021-12-16 18:06:26 UTC; 24h ago

      In the next step, you’ll connect to your proxy at last.

      Step 3 — Connecting through Dante

      In order to demonstrate your Dante server, you’ll use a command line program called curl, which is popular for making different types of web requests. In general, if you want to verify whether a given connection should be working in a browser under ideal circumstances, you should always test first with curl. You’ll be using curl on your local machine in order to do this – it’s installed by default on all modern Windows, Mac, and Linux environments, so you can open any local shell to run this command:

      • curl -v -x socks5://your_dante_user:your_dante_password@your_server_ip:1080 http://www.google.com/

      Output

      * Trying 138.197.103.77... * TCP_NODELAY set * SOCKS5 communication to www.google.com:80 * SOCKS5 connect to IPv4 142.250.189.228 (locally resolved) * SOCKS5 request granted. * Connected to 138.197.103.77 (138.197.103.77) port 1080 (#0) > GET / HTTP/1.1 …

      The credentials that you used for curl should now work anywhere else you might want to use your new proxy server.

      Conclusion

      In this tutorial, you learned to deploy a popular, open-source API endpoint for proxying traffic with little to no overhead. Many applications have built-in proxy support (often at the OS level) going back decades, making this proxy stack highly reusable.

      Next, you may want to learn how to deploy Squid, an HTTP proxy which can run alongside Dante for proxying different types of web traffic.

      Because one of the most common use cases for proxy servers is proxying traffic to and from different global regions, you may want to review how to use Ansible to automate server deployments next, in case you find yourself wanting to duplicate this configuration in other data centers.



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