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181 lines
6.9 KiB
ReStructuredText
=======================
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Setup Transparent Proxy
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=======================
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OPNsense offers a powerful proxy that can be used in combination with category
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based web filtering and any ICAP capable anti virus/malware engine. The proxy
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can be configured to run in transparent mode, this mean the clients browser does
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not have to be configured for the web proxy, but all traffic is diverted to the
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proxy automatically by utilizing Network Address Translation.
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In this How To, we will explain the basic HTTP as well as HTTPS (SSL bump) transparent
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proxy modes.
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.. Warning::
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The Transparent SSL/HTTPS proxy mode uses a technique also called man-in-the-middle,
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only configure and use this if you know what you are doing. When configured incorrectly
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you may end up in lessening your security defenses significantly instead of enhancing
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them. Using a transparent HTTPS proxy can be a dangerous practice and may not be
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allowed by the services you use, for instance e-banking.
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Step 1 - Basic Proxy Setup
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--------------------------
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To setup the transparent mode(s) a functional basic proxy setup is required.
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For basic configuration please refer to :doc:`cachingproxy`.
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Step 2 - Transparent HTTP
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--------------------------------
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Go to **Services->Proxy->Administration**
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Then select **General Forward Settings** under the **Forward Proxy Tab**.
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Select **Enable Transparent HTTP proxy**
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And Click **Apply**.
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Step 3 - NAT/Firewall Rule
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---------------------------------
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A simple way to add the NAT/Firewall Rule is to click the **(i)** icon on the
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left of the **Enable Transparent HTTP proxy** option and click on **add a new firewall rule**.
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.. image:: images/screenshot_enable_transparent_http.png
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:width: 100%
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**For reference, these are the default settings:**
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============================ =================================
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**Interface** LAN
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**Protocol** TCP
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**Source** LAN net
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**Source port range** any - any
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**Destination** any
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**Destination port range** HTTP - HTTP
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**Redirect target IP** 127.0.0.1
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**Redirect target port** other/3128
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**Description** redirect traffic to proxy
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**NAT reflection** Enable
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**Filter rule association** Add associated filter rule
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============================ =================================
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The defaults should be alright, just press **Save** and **Apply Changes**.
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Step 4 - CA for Transparent SSL
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--------------------------------------
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Before we can setup transparent SSL/HTTPS proxy we need to create a Certificate
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Authority. Go to **System->Trust->Authorities** or use the search box to get there
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fast.
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.. image:: images/search_ca.png
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:width: 100%
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Click on **add or import ca** in the upper right corner of the screen to create
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a new CA.
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For our example we use the following data:
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======================== ===========================================
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**Descriptive name** OPNsense-SSL
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**Method** Create an internal Certificate Authority
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**Key length (bits)** 2048
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**Digest Algorithm** SHA256
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**Lifetime (days)** 356
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**Country Code** NL (Netherlands)
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**State or Province** Zuid Holland
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**City** Middelharnis
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**Organization** OPNsense
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**Email Address** spam@opnsense.org
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**Common Name** opnsense-ssl-ca
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======================== ===========================================
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**Save**
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Step 5 - Transparent SSL
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-------------------------------------
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Go to **Services->Proxy->Administration**
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Then select **General Forward Settings** under the **Forward Proxy Tab**.
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Select **Enable SSL mode** and set **CA to use** to the CA you have just created.
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Then Click **Apply**.
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Step 6 - Configure No SSL Bump
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------------------------------
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This step is very important and requires careful consideration!
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To make sure that known sites are not bumped and keep their original security layer
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intact, one needs to add those including all subdomain to the **SSL no bump sites**
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field.
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To enter a new item type in the field and hit enter to accept. start with a . (dot)
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to add all subdomains as well. Example: To add all of paypal.com , type .paypal.com
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and hit enter.
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.. Note::
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Make sure that all banking sites and sites that you provide personal or login
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information for are added to this field. If you are not sure what to add, please
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reconsider using transparent SSL as its clearly not intended for you!
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Step 7 - SSL NAT/Firewall Rule
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-------------------------------------
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A simple way to add the NAT/Firewall Rule is to click on the **(i)** icon on the
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left of the **Enable SSL mode** option and click on **add a new firewall rule**.
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.. image:: images/screenshot_enable_transparent_http.png
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:width: 100%
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**For reference, these are the default settings:**
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============================ =================================
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**Interface** LAN
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**Protocol** TCP
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**Source** LAN net
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**Source port range** any - any
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**Destination** any
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**Destination port range** HTTPS - HTTPS
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**Redirect target IP** 127.0.0.1
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**Redirect target port** other/3129
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**Description** redirect traffic to proxy
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**NAT reflection** Enable
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**Filter rule association** Add associated filter rule
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============================ =================================
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The defaults should be alright, just press **Save** and **Apply Changes**.
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Step 8 - Configure OS/Browser
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-----------------------------
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Since the CA is not trusted by your browser, you will get a message about this
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for each page you visit. To solve this you can import the Key into your OS and
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set as trusted. To export the Key go to **System->Trust->Authorities** and click
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on the icon to export the CA certificate. Of course one may choose to accept the
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certificate for each page manually, but for some pages that may not work well unless
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not bumped.
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.. image:: images/export_CA_cert.png
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Import and change trust settings on your favorite OS. For example, on macOS it looks
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like this:
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.. image:: images/Trust_Settings_OSX.png
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:width: 100%
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.. Warning::
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Again be very careful with this as your system will accept any page signed with
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this CA certificate. As long as no-one gains access to the private key that
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is no problem, but if any one can get a get a hold of it then all traffic
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can be decrypted except those in the *do not bump* list. You have been warned!
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.. Note::
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On Android devices, you may get notified about the device being unable to access
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the internet. This happens because the certificates are pinned to protect the
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connection against man in the middle attacks otherwise trusted certificates.
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If you want to make the connection work again, you have to whitelist the following
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Google domains in your "No Bump Hosts" settings.
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* Your local Google domain (for example: google.at for Austria, google.de for Germany, …)
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* .google.com
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* .googleapis.com
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* .gstatic.com
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* .1e100.net
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**DONE**
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