[Dovecot] compressed IMAP traffic

Leonardo Rodrigues leolistas at solutti.com.br
Mon Sep 28 22:09:31 EEST 2009


Timo Sirainen escreveu:
>
> And DEFLATE gives the exact same error? LZO isn't supported by OpenSSL.
>
>   
    yes ... error from DEFLATE and LZO are exactly the same on 
gnutls-cli output and maillog on the CentOS 5.3 box.

> Well, not the same server but looks like this one works too:
>
> gnutls-cli --priority NORMAL:+COMP-DEFLATE -p 993 secure.emailsrvr.com
>
> And just for fun I tried imap.gmail.com, that didn't support
> compression.
>   

    i had tried imap.gmail.com too :)

    interesting findings ..... from CentOS 5.3, i cant get any 
compression method to work:

[root at correio dovecot]# gnutls-cli --insecure -p 993 -p 993 
secure.emailsrvr.com --comp LZO DEFLATE NULL 
[ ......]
- Version: TLS 1.0
- Key Exchange: DHE RSA
- Cipher: AES 256 CBC
- MAC: SHA
- Compression: NULL

    but from a Fedora 8 box:

[root at correio ~]# gnutls-cli --insecure -p 993 -p 993 
secure.emailsrvr.com --comp LZO DEFLATE NULL
[ ......]
- Version: TLS 1.0
- Key Exchange: DHE RSA
- Cipher: AES 256 CBC
- MAC: SHA
- Compression: DEFLATE


    and Fedora 8 OpenSSL is even older than CentOS 5.3 one:

CentOS 5.3:
[root at correio dovecot]# rpm -qi openssl
Name        : openssl                      Relocations: (not relocatable)
Version     : 0.9.8e                            Vendor: CentOS
Release     : 12.el5                        Build Date: Fri 04 Sep 2009 
09:33:56 AM BRT

Fedora 8:
[root at correio ~]# rpm -qi openssl
Name        : openssl                      Relocations: (not relocatable)
Version     : 0.9.8b                            Vendor: Fedora Project
Release     : 17.fc8                        Build Date: Mon 15 Oct 2007 
07:56:22 PM BRST

    probably there's some build option on CentOS that is disabling 
compression. If 0.9.8b on Fedora8 built in October/2007 can do it, so 
0.9.8e on CentOS 5.3 built on September/2009 should be able to do it too 
....... oh boy, i really hate those weirds compilation options from 
Redhat  .... :\

-- 


	Atenciosamente / Sincerily,
	Leonardo Rodrigues
	Solutti Tecnologia
	http://www.solutti.com.br

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