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How to Append the Port to the Host Header in a Health Check

When configuring Real Server health checks, the LoadMaster Web User Interface (WUI) does not allow the port to be included in the host header. There are limitations that prevent the port from being appended to the host name when this is configured from the LoadMaster WUI.

The HTTP/1.1 field does not allow for the port number in versions prior to 7.2.40. You would see an “Invalid Checkhost address” error if the port is entered here. Our objective is to bypass this error. 



A. Modify the Virtual Service (VS). Check the Use HTTP/1.1 box under Real Servers. Leave the HTTP/1.1 Host field blank for now.


B. Using the Application Program Interface (API):

  1. In the WUI, enable the API interface:
    • Certificates & Security > Remote Access > Enable API Interface
  2. Open a new web browser tab and type the URL or IP address of the LoadMaster's admin interface followed by /access/modvs?vs=<VS_ID>&checkhost=<hostname>:8443
    • For example: https://<LM_URL_or_IP_Address>/access/modvs?vs=<VS_ID>&checkhost=<hostname>:8443
  3. Press Enter.
  4. Ensure the XML doc provides a SUCCESS, not a FAIL.

      5. On the VS under Real Servers, check the HTTP/1.1 Host area to confirm the correct Host:port/path combination.

C. Using the LoadMaster Command Line Interface (CLI) 

  1. Access the console of the LoadMaster (not the WUI) as the bal user
  2. Get to the CLI by pressing (2) and ENTER
  3. Use the following commands:
  • vip <VS IP:port#> OR <VS-ID>
  • checkhost <host:port>
  • exit
  • end
  • (q) Exit Configuration

For example: vip

For example: checkhost


      5. On the VS, under Real Servers, check the HTTP/1.1 Host text box to confirm the correct Host:port/path combination.


Finding the VS ID:

Virtual Services > View/Modify > Modify. The VS ID is listed at the top of the screen.

(Id:x) where x = the VS ID.

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