On 2021-01-06 at 14:23 +0100, Dan Malm via mailop wrote: > This might have some implications for anyone running a mail server on > Ubuntu as smtp delivery to recipients with a "legacy" SSL configuration > will break with SSL errors like for example: "SSL > routines:tls_process_ske_dhe:dh key too small" > > Just thought I'd spare others some troubleshooting in case you run in to > this, and see if anyone else have any thoughts on it. :)
Debian use Exim and used to patch it to set the DH side to 2048 and also set the _minimum_ to 2048. With Exim 4.82 (in 2013), the upstream Exim introduced a Transport option tls_dh_min_bits to set the minimum explicit size correctly, and we worked with the Debian folks so that future releases would raise their own standard but force up the minimum acceptable. In 2021, I might consider raising the minimum acceptable. The point though is that we've had MTAs enforcing 2048 before with no noticeable impact, but it's plausible that at the time there were few enough other MTAs running DHE that there simply wasn't the install base to expose issues. -Phil _______________________________________________ mailop mailing list mailop@mailop.org https://list.mailop.org/listinfo/mailop
