Re: SSL Compression - doesn't work?

[Krystian Bigaj <krystian.bigaj@xxxxxxxxx>]

I've build OpenSSL with zlib (perl Configure VC-WIN32 no-asm zlib-dynamic --prefix=...) and now compression works correctly.

After executing:

SELECT lpad('', 1024*1024, 'A')

there is only about 13kB of TCP transfer instead of ~1MB.

Thanks again!

However I'm still curious why windows build doesn't have this enabled by default. Is it a potential compatibility issues, or just an oversight?

I would like to see a note in docs about that issue. I've read that docs about sslcompression before, also I knew that PG on Windows is build with zlib support (for pg_dump/pg_restore), and because of this I wrongly assumed that OpenSSL is build with zlib too. Additionally that "Encryption=SSL encrypted" and "SSL Compression=yes" in pgAdmin made me think that it's a bug in PG.

Best regards,
Krystian Bigaj

On 8 May 2014 17:28, Terence Ferraro <terencejferraro@xxxxxxxxx> wrote:

You mentioned you are using the Windows version; unless something has changed recently in their build process, the included openssl library is not linked against zlib and therefore compression is not possible unless you recompile the Windows version yourself.

Terence J. Ferraro

On Thu, May 8, 2014 at 9:36 AM, Adrian Klaver <adrian.klaver@xxxxxxxxxxx> wrote:

On 05/08/2014 01:22 AM, Krystian Bigaj wrote:

Hi,

I'm wondering how, and if SSL compression works correctly.

Here is how I tested it:
- PostgreSQL 9.3.4 x86 on Windows 7 x64
- .crt/.key files by openssl, and placed in database cluster folder
- postgres.exe ran with: --ssl="on" --ssl_cert_file="test.crt"
--ssl_key_file="test.key"
- connection made by pgadmin with SSL=prefer, SSL Compression=True
- when connected I see in properties: Encryptions=SSL encrypted, SSL
Compression=yes
- I've dumped TCP transfer and I can tell that data is encrypted

Now when I run query like:
SELECT lpad('', 1024*1024, 'A')

then I see that there is a TCP transfer of 1,01MB (so 1MB of string
data, and some pg header/data).

If I turn off SSL Compression data transfer between postgres and pgadmin
is still 1,01MB (but in properties I see SSL Compression=no)

It looks like SSL compression doesn't work, or am I missing something?

http://www.postgresql.org/docs/9.3/static/libpq-connect.html

sslcompression

    If set to 1 (default), data sent over SSL connections will be compressed (this requires OpenSSL version 0.9.8 or later). If set to 0, compression will be disabled (this requires OpenSSL 1.0.0 or later). This parameter is ignored if a connection without SSL is made, or if the version of OpenSSL used does not support it.

So what version of OpenSSL are you using?

Best regards,
Krystian Bigaj

--
Adrian Klaver
adrian.klaver@xxxxxxxxxxx


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