dh key too small

[Kcchouette]

When creating a new certificate, we use the script `linux/generate_certs.sh`
It uses this command:
 $ openssl dhparam -outform PEM -out dhparam.pem 1024
which mean "use a Diffie-Hellman key of 1024 bits"

Sadly, Logjam Attack occurs on DH key <=1024 bits.
In the way to "fix" that, debian software can't connect anymore on ADCS hub that have a DH key <=1024 bits.

See https://weakdh.org/ for more security info, but tldr:
 > If you run a server… [...] you should disable support for export cipher suites and use a 2048-bit Diffie-Hellman group.

You can so fix the issue by modifying
 $ openssl dhparam -outform PEM -out dhparam.pem 1024
to
 $ openssl dhparam -outform PEM -out dhparam.pem 2048

Cheers

[maksis (maksis)]

Related: https://github.com/airdcpp-web/airdcpp-webclient/issues/333

[Kcchouette (kcchouette)]

Do not forget to update your website this part: http://adchpp.sourceforge.net/user_guide/basic_guide.html#_setting_up_ports

 $ openssl dhparam -outform PEM -out dhparam.pem 1024
to
 $ openssl dhparam -outform PEM -out dhparam.pem 2048

[eMTee (realprogger)]

Fixed in ADCH++ 3.0.0