[AusNOG] Optusnet TLS mail - DH key size too small

Mark Stewart mark at nabc.com.au
Mon Nov 15 15:05:48 EST 2021

Good morning / afternoon!

Is there a mail admin for Optus on the list? I'm having an issue communicating to the extmail.optusnet.com.au servers via STARTTLS.

I'm getting an error of "routines:tls_process_ske_dhe:dh key too small" when attempting to connect.

SSL handshake seems happy but due to the DH being too small, it rejects the connection. See: https://weakdh.org/


Mark Stewart

PO Box 486, WANNEROO WA 6946
m: 0438 005 415
e: mark at nabc.com.au<mailto:mark at nabc.com.au>
w: www.nabc.com.au<http://www.nabc.com.au>

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