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:  </p>

Your IP address is: 18.216.208.243

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.

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 18.216.208.243

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

SSI source	displays
<p> Your IP address is: <!--#echo var="REMOTE_ADDR" --> </p>	Your IP address is: 18.216.208.243

variable	meaning	value
SERVER_NAME	Server name	humphryscomputing.com
SERVER_ADDR	Server IP	78.128.60.189
REMOTE_ADDR	Client IP	18.216.208.243
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)