pfSense Load Balancing: Part Three (Web Server Failover)

In parts one and two of this series, I demonstrated how to configure a gateway group for the WAN gateway. In this article, I will cover setting up a cluster for web server failover using pfSense load balancing.

Web Server Failover, Step One: Add the Monitor

Web Server Failover

Setting up the monitor for our web server failover.

First, navigate to Services -> Load Balancer and click on the “Monitors” tab. Here you will see several predefined entries: ICMP (Internet Control Message Protocol), TCP, HTTPS, and SMTP (Simple Mail Transfer Protocol). Click the “plus” button to add a new entry. At “Name“, specify a name, and at “Description“, enter an appropriate description. At “Type“, set the type to HTTP, and set the “Host” to the IP address of the primary web server. Leave “Path” unchanged, and at “HTTP Code“, leave the code as “200 OK”. Press the “Save” button to save changes and on the next screen, press “Apply changes” if necessary.

Web Server Failover, Step Two: Add the Web Server Pool

Web Server Failover

Setting up a simple pool with a primary and backup web server.

Next, click on the “Pools” tab. Click the “plus” button to add a new pool. At “Name“, specify an appropriate name, and at “Mode“, set the mode to “Manual Failover“. At “Description“, add an appropriate description. Since this is a web server failover pool, at “Port” enter 80. You can leave “Retry” blank, or optionally set the number of retries. Under “Add Item to Pool“, set “Monitor” to whatever you named the monitor as in the previous step (in my case “WebsiteFailover“). At “Server IP Address“, add the IP address of the primary web server and click the “Add to pool” button. Then add the IP address of the backup web server and click the “Add to pool” button. The backup server will show up in the “Pool Disabled” text box. Then press the “Save” button to save the changes and press the “Apply changes” button if necessary on the next page.


Web Server Failover, Step Three: Add the Virtual Server

Next, click the “Virtual Servers” tab and click the “plus” button to add a new virtual server. At “Name“, specify an appropriate name and at “Description“, add a description. At “IP address“, set the appropriate address (most likely this will be the WAN IP, so I typed 192.168.3.1 here). At “Port“, type 80, since this is for web server failover. “At Virtual Server Port“, select the web server pool created in the previous step. Leave “Fail Back Pool” unchanged (none) and leave “Relay Protocol” unchanged (tcp). Press the “Submit” button to submit changes and “Apply changes” on the next page if necessary.

Web Server Failover, Step Four: Add the Firewall Rule

Web Server Failover

Adding a firewall rule to allow traffic to pass through to the web servers.

Finally, we must create a firewall rule for the newly-created virtual server. It would be handy to create a an alias for both the primary and backup web server, so first navigate to Firewall -> Aliases. At “Name” enter a name (I chose “VirtualApache”), and at “Description“, enter a description. Leave “Type” unchanged, and at “Hosts“, enter the IP addresses of both the primary and backup web servers (in my example, 192.168.3.20 and 192.168.3.21). Then press the “Save” button to save, and “Apply changes” if necessary.

Navigate to Firewall -> Rules and click the plus button to create a new firewall rule. As “Action“, select “pass” in the drop-down box. At “Interface“, select “WAN” or whatever is being used as the WAN gateway. At “Protocol“, leave the protocol as “TCP”. At “Source“, leave the “Type” as “any” and click on the “Advanced” button to show the source port range. Select “any” in the drop-down box and type 80 in the top edit box (alternatively, you could select “HTTP” in the drop-down box). At “Destination“, select “Single host or alias” as the “Type“, and at “Address” type the alias you defined above (in my case, VirtualApache). You do not need to specify a “Destination port range” and you should probably leave “Log packets that are handled by the rule” unchecked. At “Description“, enter an appropriate description and click the “Save” button. If necessary, click “Apply changes” on the next page. If you want to pass HTTP Secure (HTTPS) traffic, then you will need to create an additional rule. If so, then follow the steps outlined above, but for the source port range, type 443 or select “HTTPS” in the drop-down box.

Conclusion

Now that configuration is complete, pfSense is set up to automatically redirect traffic from the primary web server to the backup web server in the event of a failure. The pool defines the location of the web servers and the failover mode. The virtual server defines the IP addresses used in the NAT and firewall rules to listen for HTTP traffic, which the virtual server redirects to the pool. The monitor will check on the status of the primary web server by periodically making a web request. If it gets back a “200 OK” code, then the pool will send traffic to the primary server; otherwise, it will send traffic to the backup.

Other Articles in This Series:

pfSense Load Balancing: Part Three (Web Server Failover)

pfSense Load Balancing: Part Two

External Links:

Inbound Load Balancing at doc.pfsense.org”>

pfSense Load Balance Fail-Over Setup

Load Balance and Cluster Failover Webserver (includes how to set up and install pfSense)

How to Use pfSense to Load Balance Your Web Servers

 

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