Login bug on some sites with TLSv1 v5.1.0 /Build 3861)

I get the following connect error with the newest (just updated) version

[09:04:32] [L] Connected to site
[09:04:32] [L] 220 FTP server ready.
[09:04:32] [L] AUTH SSL
[09:04:32] [L] 234 AUTH SSL successful
[09:04:32] [L] SSL error:14082174:SSL routines:ssl3_check_cert_and_algorithm:dh key too small
[09:04:32] [L] Failed TLSv1 negotiation, disconnected
[09:04:32] [L] Connection failed (Connection closed by client)

this hinders me from connecting to the site.

any ideas ?

Regards,
Emil

This was a security fix introduced in the latest OpenSSL update to prevent LogJam attack via a weak dh key
more information can be found at https://weakdh.org/

Most likely the server needs to re-generate a new X.509 certificate for SSL encryption with a stronger key, 1024 and up.

Alternatively you could downgrade OpenSSL to an older insecure version to gain access to the FTP server but security will be very weak and not recommended.

Yes, you are right, I luckily found an older build of flashfxp and installed that ,until I can get around to upgrading the site in question. It would have been nice if I could have downloaded older builds from your site, say top 5 recent builds ?

Regards,
Emil

You don't need an older build of FlashFXP, just an older build of the OpenSSL DLLs

http://archive.flashfxp.com/archives/openssl/

Unzip the desired version into your FlashFXP program folder replacing the existing DLLs

The link above also includes older builds of FlashFXP as well.

I should point out it would probably be best to install the portable edition of FlashFXP into a special folder and only downgrade openssl on that copy so you can connect to the site that requires weak security.

This way you're limiting the weak security to that single instance of FlashFXP when connecting to a specific site and still maintaining maximum security on the rest of the sites you connect to when using your normal installation.

Originally Posted by emile42

Yes, you are right, I luckily found an older build of flashfxp and installed that ,until I can get around to upgrading the site in question. It would have been nice if I could have downloaded older builds from your site, say top 5 recent builds ?

Regards,
Emil

You should really update your SSL configuration right away instead of switching to an insecure version of OpenSSL.
What's the point of having encryption if it's not secure. Might as well just completely turn it off.