SSI environment variables demo

SSI can be used to echo environment variables that exists on the server.

SSI source	displays
<p> Your IP address is: <!--#echo var="REMOTE_ADDR" --> </p>	Your IP address is: 3.15.14.33

The text is substituted at this point, before the HTML is sent to the client.
View Source to see that the IP was inserted before the HTML went to the client.

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More examples

Below are various examples.
You cannot see the SSI source but you can guess it.

View Source to see that the variables were inserted before the HTML went to the client.

variable	meaning	value
SERVER_NAME	Server name	humphryscomputing.com
SERVER_ADDR	Server IP	78.128.60.189
REMOTE_ADDR	Client IP	3.15.14.33
REMOTE_HOST	Client name	(none)
HTTP_X_FORWARDED_FOR	Client original IP	(none)
LAST_MODIFIED	This page last modified (SSI knows this. JS only knows this if the server tells it in the HTTP header.)	Sunday, 03-Apr-2022 15:47:19 IST
HTTP_REFERER	Referring page	(none)
HTTP_USER_AGENT	User agent string	Mozilla/5.0 AppleWebKit/537.36 (KHTML, like Gecko; compatible; ClaudeBot/1.0; +claudebot@anthropic.com)

• Server-side environment variables
• php.net has a list of these