How to test deflate/gzip compression on a HTTPS (HTTP over SSL) Apache server

To test a server for deflate/gzip compression, it needs to be notified that you, as a client (browser) accept compressed encoding.

This is done, by adding an "Accept-Encoding: compress, gzip" in the header of the request.

Testing an https Apache server for deflate/gzip compression, initiating a connection using openssl client

Code:

$ openssl s_client -connect  192.168.1.1:443 
...Some output about ssl certificate and ssl protocol and cipher used....
GET / HTTP/1.1
Host: test.server.ro
Accept-Encoding: compress, gzip -->press RETURN
-->press RETURN again


HTTP/1.1 200 OK
Date: Tue, 03 Aug 2010 07:17:45 GMT
Server: Apache
X-Powered-By: PHP/5.2.9
Set-Cookie: SQMSESSID=8e7a8619ba2821ea61c4f24f7dbc2467; path=/
Expires: Thu, 19 Nov 1981 08:52:00 GMT
Cache-Control: no-store, no-cache, must-revalidate, post-check=0, pre-check=0
Pragma: no-cache
Set-Cookie: SQMSESSID=8e7a8619ba2821ea61c4f24f7dbc2467; path=/; secure; HttpOnly

Vary: Accept-Encoding
Content-Encoding: gzip
Content-Length: 1022
Content-Type: text/html; charset=iso-8859-1
?Vmo?6??_q?04if?Z?v?%h?a?.X=C?DIL(R%)'????#?7%???d?w??=|???ٟ??.?????\??????0
                                                                            ??????;8   F?4??[?$a8?H&?A\?Z?7??d??R??f   ?*U?Ȕ?LڄH?e????PB?;?????H?????1K?>4??{CT?      ??V?f?m?
Th,??7????@A?ac<-Z?9^?|i??rj??\8???J            ?s*?0?cYn??/??Y?!\???8?b?i?XT?--?????f??;[??p8XP
E?C??r?P#%???J?????֪?Y?ٹf??
                          *Z?H/??c??
                                    8??q???V????銘

The line that shows us that the HTTPS Apache server is sending compressed information (besides the output obviously) is:

Code:

Content-Encoding: gzip

As I stated, it is very important to inform the server that you accept compressed content, otherwise the server will send plain text. To advertise this, just add Accept-Encoding: compress, gzip in the request's header.

To test without advertising that compressed content is accepted, the https server will just send the same page in plain text:

Code:

$ openssl s_client -connect  192.168.1.1:443 
...Some output about ssl certificate and ssl protocol and cipher used....
GET / HTTP/1.1
Host: test.server.ro -->press RETURN
-->press RETURN again

HTTP/1.1 200 OK
Date: Tue, 03 Aug 2010 07:24:01 GMT
Server: Apache
X-Powered-By: PHP/5.2.9
Set-Cookie: SQMSESSID=5a31331a117256cbbfd26e4180287ccc; path=/
Expires: Thu, 19 Nov 1981 08:52:00 GMT
Cache-Control: no-store, no-cache, must-revalidate, post-check=0, pre-check=0
Pragma: no-cache
Set-Cookie: SQMSESSID=5a31331a117256cbbfd26e4180287ccc; path=/; secure; HttpOnly
Vary: Accept-Encoding
Content-Length: 2369
Content-Type: text/html; charset=iso-8859-1

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