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    Set Up Your Explicit Proxy PAC File
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    5. Explicit Proxy on Prisma Access
    6. Set Up Your Explicit Proxy PAC File
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    Set Up Your Explicit Proxy PAC File

    Table of Contents

    Set Up Your Explicit Proxy PAC File

    Describes the PAC file requirements used to successfully deploy Prisma Access Explicit Proxy.
    Use the following guidelines and requirements when configuring the PAC file to use with Explicit Proxy:
    • PAC files are required to steer user traffic to Explicit Proxy.
    • You can only host one PAC file for use with Prisma Access, and the Explicit Proxy PAC file is hosted in the United States. If you require alternative PAC file access outside of the United States, you can host the PAC file in your enterprise.
    • Only ASCII text format is supported for PAC files. Palo Alto Networks recommends that you create and save the PAC file in a text editor such as VI or Vim.
    • Upload the PAC file after you create your Explicit Proxy configuration and commit and push your changes. After you upload your PAC file, a commit and push operation is not required.
    • You must have at least one Explicit Proxy URL in the
      return "PROXY foo.proxy.prismaaccess.com:8080";
       statement beginning for traffic ingressing to Prisma Access. Either use a configured domain used when you push your changes or use a valid IPv4 address or DIRECT keyword such as
      PROXY paloaltonetworks-245139.proxy.prismaaccess.com:8080
       or
      PROXY 1.2.3.4:8080
      , and so on.
    • If the proxy is not being bypassed, then the you must provide a PROXY keyword. A valid proxy statement is required if no
      DIRECT
       keyword is configured for the proxy bypass.
    • If a valid PROXY statement is found before an invalid PROXY statement, Explicit Proxy skips the validity check all on all PROXY statements after the first. For example, a PAC file with the valid statement
      PROXY paloaltonetworks-245139.proxy.prismaaccess.com:8080
       followed by the invalid statement
      PROXY foo.proxy.prismaacess.com:8080
       would be considered valid since Explicit Proxy skips the validity check for
      foo.proxy.prismaacess.com:8080
      .
    • If you are using a PROXY statement to have ACS traffic bypass the Prisma Access proxy, the PROXY statement should not use the Explicit Proxy URL. In this configuration, Explicit Proxy provides an error message, but allows you to upload the PAC file. You can direct the ACS traffic to other proxies using a valid FQDN or IPv4 address, or directly to the internet, using the
      DIRECT
       keyword.
    • Only IPv4 addresses are supported in PROXY statements. Do not use IPv6 addresses in PROXY statements.
    • The maximum file size for a PAC file is 256 KB.
    • You must specify IdP and ACS URLs to be bypassed.
    • You cannot delete a PAC file after you're uploaded it. You can, however, upload a new PAC file to overwrite the existing one.
    • If you change the Explicit Proxy URL in Prisma Access but do not change the PAC file to reflect the change, the change won't be applied. You must upload a new PAC file specifying the new Explicit Proxy URL.
    Explicit Proxy provides you with a sample PAC file that you can modify and use as the PAC file for your Explicit Proxy deployment. The sample PAC file that Prisma Access provides contains the following data:
    function FindProxyForURL(url, host) { 
    /* Bypass localhost and Private IPs */ 
    var resolved_ip = dnsResolve(host); 
    if (isPlainHostName(host) || 
    shExpMatch(host, "*.local") || 
    isInNet(resolved_ip, "10.0.0.0", "255.0.0.0") || 
    isInNet(resolved_ip, "172.16.0.0",  "255.240.0.0") || 
    isInNet(resolved_ip, "192.168.0.0",  "255.255.0.0") || 
    isInNet(resolved_ip, "127.0.0.0", "255.255.255.0")) 
    return "DIRECT"; 
    /* Bypass FTP */ 
    if (url.substring(0,4) == "ftp:") 
        return "DIRECT"; 
    /* Bypass SAML, e.g. Okta */ 
    if (shExpMatch(host, "*.okta.com") || shExpMatch(host, "*.oktacdn.com")) 
        return "DIRECT"; 
        /* Bypass ACS */ 
    if (shExpMatch(host, "*.acs.prismaaccess.com")) 
        return "DIRECT"; 
    /* Forward to Prisma Access */ 
    return "PROXY foo.proxy.prismaaccess.com:8080";
    If you want to use the default PAC file that Prisma Access provides, you can optionally modify the fields in the PAC file as described in the following table.
    Text
    Description
     
    var resolved_ip = dnsResolve(host); 

...

return "DIRECT";
    Enter any hostnames or IP addresses that should not be sent to Explicit Proxy between the JavaScript functions
    var resolved_ip =
     and
    return “DIRECT”;
    .
    If you do not modify the data in this file, the following hostnames and IP addresses bypass Explicit Proxy:
    • if (isPlainHostName(host)
      —Bypasses Explicit Proxy for hostnames that contain no dots (for example, http://intranet).
    • shExpMatch(host, "*.local") ||
      —Bypasses the proxy for any hostnames that are hosted in the internal network (localhost).
    • isInNet(resolved_ip, "10.0.0.0", "255.0.0.0") || isInNet(resolved_ip, "172.16.0.0", "255.240.0.0") || isInNet(resolved_ip, "192.168.0.0", "255.255.0.0") || isInNet(resolved_ip, "127.0.0.0", "255.255.255.0"))
      —Bypasses Explicit Proxy for any IP addresses that are in the private or loopback IP address range. 
    if (url.substring(0,4) == "ftp:") 
return "DIRECT";
    Bypasses Explicit Proxy for FTP sessions.
    if (shExpMatch(host, "*.okta.com") || shExpMatch(host, "*.oktacdn.com")) 
return "DIRECT";
    Bypasses Explicit Proxy for the SAML IdP. Be sure to add all FQDNs used by the IdP.
    If you use Okta as the IdP used for SAML authentication, enter
    *.okta.com
     and
    *.oktacdn.com
    . 
    if (shExpMatch(host, "*.acs.prismaaccess.com")) 
return "DIRECT";
    Bypasses Explicit Proxy for the Prisma Access Authentication Cache Service (ACS).
    Instead of using a wildcard, you can add the specific
    ACS FQDN
     for your deployment. Find this FQDN under
    Panorama
    Cloud Services
    Status
    Network Details
    Mobile Users—Explicit Proxy
    ACS FQDN
    .
    return "PROXY foo.proxy.prismaaccess.com:8080"
    Bypasses Explicit Proxy for the Explicit Proxy URL.
    You must have at least one Explicit Proxy URL in the
    return "PROXY foo.proxy.prismaaccess.com:8080";
     statement for traffic ingressing to Prisma Access. Either use a configured domain used when you push your changes, or use a valid IPv4 address or DIRECT keyword such as
    PROXY paloaltonetworks-245139.proxy.prismaaccess.com:8080
     or
    PROXY 1.2.3.4:8080
    .

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