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Barracuda CloudGen Firewall

How to Set Up a Reverse Proxy

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In Reverse Proxy mode, the proxy directs incoming requests from other servers to the client without providing the origin details. To set up a reverse proxy using the Barracuda NextGen Firewall F-Series, configure the listening port and reverse proxy settings.

Before You Begin

Verify that you activated the HTTP Proxy service in reverse proxy mode. For instructions, see How to Set Up and Configure the HTTP Proxy.

Configure the Listening Port

In the settings for the HTTP Proxy, use TCP listening port 80.

  1. Go to CONFIGURATION > Configuration Tree > Box > Virtual Servers > your virtual server > Assigned Services > HTTP Proxy > HTTP Proxy Settings.
  2. In the left menu, select IP Configuration.
  3. Click Lock.
  4. In the TCP Listening Port field, enter 80. Verify that you have port 80 available for your reverse proxy.
  5. When you change the listening port, you must also change the port used in host firewall rule OP-SRV-PX. By default, the rule uses TCP 3128. If you want to use HTTP, change TCP 3128 to HTTP. If you want to use HTTP and HTTPS, change TCP 3128 to HTTP+S. For more information on configuring Host Firewall rules, see Host Firewall.
  6. Click Send Changes and Activate.

Configure Reverse Proxy Settings

To configure the reverse proxy settings:

  1. Go to CONFIGURATION > Configuration Tree > Box > Virtual Servers > your virtual server > Assigned Services > HTTP Proxy > HTTP Proxy Settings.
  2. In the left menu, select Reverse Proxy Settings.
  3. Click Lock
  4. Specify your Reverse Proxy Settings. For more information on these settings, see the following Reverse Proxy Settings section.
  5. Click Send Changes and Activate.

Reverse Proxy Settings

The following table provides more detailed descriptions of the Reverse Proxy Settings:

SettingDescription
Backend Web SiteEnter the IP address of the internal webserver behind the reverse proxy.  If there is no host header, enter your primary domain (for example, mydomain.com).
ACL Mode

Select the ACL mode:

  • Default – Access to the backend website is allowed automatically.
  • Advanced Access is allowed according to the configured access policy configured in the HTTP Proxy Settings > Access Control section. 
Use SSL

Select yes from the Use SSL list to provide HTTPS and HTTP support for the reverse proxy. Import your certificate and key by clicking Ex/Import for SSL Certificate and SSL Private Key.

Switch to Advanced View and click on SSL Settings in the left menu to configure SSL cipher settings. When set to Disallow Weak Ciphers (default), the following cipher string is used:

!aNULL:ALL:!EXPORT:!LOW:!MEDIUM:!RC2:!3DES:!DSS:!SEED:!RC4:!PSK:@STRENGTH

SSL Listening portThe SSL listening port (default: 443).
SSL CertificateWhen using SSL, import a certificate for securing the connection. This should be the certificate of the backend website.
SSL Private Key Type

Select the type of private key that belongs to the certificate.

  • When selecting RSA, import the private RSA key.
  • When selecting ECDSA, import the private ECDSA key.
SSL/TLS Version for BackendSelect the SSL or TLS version to be used for the backend. To let the proxy determine the version, select Auto.
Custom Cipher String for BackendEnter a custom colon-separated string of ciphers. This setting is only valid for reverse proxy mode.
Front-End HTTPS HeaderSet to On to enable the front-end HTTPS header. Set to Auto to add this header if the forwarded request is using HTTPS. The front-end HTTPS header is required when using the reverse proxy for SSL offloading in front of Microsoft OWA.
MS Authentication ForwardingMicrosoft connection-oriented authentication forwarding (NTLM, Negotiate, and Kerberos)
Backend IP AddressesIn this table, add the IP addresses of your backend servers. You must add the IP address of at least one backend server.
Round Robin

Unless you want to use domain or URL-based mapping, you can enable round robin load balancing between multiple backend servers by selecting yes from the Round Robin list.

Load balancing is not available if traffic shaping is enabled on the device to which the web server is attached. For more information, see Traffic Shaping.

Pass Login to BackendSet to Yes if you want the proxy to pass on all authentication headers to the backend servers.
Additional Backend DomainsIn this table, you can add additional domains for domain-based virtual hosts.
Domain to Backend Mapping

Note that the Name field of entries in this table must not exceed 21 characters.

If you have not installed Barracuda NextGen Firewall F-Series hotfix 521, the ACL-based reverse mapping table is provided. In this table, you can add ACLs for the backend server that should be used.

To map either a domain or a specific URL to a backend server, click +, enter a descriptive name for the map (for example, DOMA04), and click OK

  • In the Backend Mappings configuration window, map either a domain or a specific URL to a backend server.
  • From the Mapping Type list, select Domain for domain to backend mapping. If you are using url-regex to backend mapping, select Url-Regex.
  • From the Domain list, select a domain that is specified in the Additional Backend Domains table. If you are using url-regex to back-end mapping, enter the regular expression to match a URL against (for example, http://example.com/foo/.*).
  • From the Backend list, select the back-end server that should handle the requests that match the above configuration. This list includes the backend servers that you entered in the Backend IP Addresses table.

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