On 2012-06-21 Eric Cooper <e...@cmu.edu> wrote: > Package: exim4 > Followup-For: Bug #676563
> This problem still exists for me in version 4.80-3. > I'm using smtp.srv.cs.cmu.edu as smarthost, and I get this error: > 2012-06-20 18:40:40 1ShRfu-0001AA-8c TLS error on connection to > smtp.srv.cs.cmu.edu [128.2.217.15] (gnutls_handshake): The Diffie-Hellman > prime sent by the server is not acceptable (not long enough). > 2012-06-20 18:40:40 1ShRfu-0001AA-8c TLS session failure: delivering > unencrypted to smtp.srv.cs.cmu.edu [128.2.217.15] (not in hosts_require_tls) > I downgraded to 4.77-1 and my configuration works again. > I tried setting tls_dh_min_bits to several lower values, but it didn't > help. (Perhaps I was doing it wrong.) Hello, With the default setting, I also see the error: (SID)root@argenau:/# exim4 -bP transport remote_smtp_smarthost | grep tls_dh_min tls_dh_min_bits = 1024 (SID)root@argenau:/# echo foo | exim -f '<>' -d+all inva...@example.com [...] 28546 SMTP>> STARTTLS 28546 waiting for data on socket 28546 read response data: size=30 28546 SMTP<< 220 2.0.0 Ready to start TLS 28546 initialising GnuTLS as a client on fd 7 28546 GnuTLS global init required. 28546 initialising GnuTLS client session 28546 Expanding various TLS configuration options for session credentials. 28546 TLS: no client certificate specified; okay 28546 TLS: tls_verify_certificates not set or empty, ignoring 28546 GnuTLS using default session cipher/priority "NORMAL" 28546 Setting D-H prime minimum acceptable bits to 1024 28546 TLS: server certificate verification not required 28546 LOG: MAIN 28546 TLS error on connection to smtp.srv.cs.cmu.edu [128.2.217.15] (gnutls_handshake): The Diffie-Hellman prime sent by the server is not acceptable (not long enough). However downgrading the security works for me: (SID)root@argenau:/# echo TLS_DH_MIN_BITS = 512 >> /etc/exim4/exim4.conf.localmacros (SID)root@argenau:/# /etc/init.d/exim4 restart [...] (SID)root@argenau:/# exim4 -bP transport remote_smtp_smarthost | grep tls_dh_min tls_dh_min_bits = 512 (SID)root@argenau:/# echo foo | exim -f '<>' -d+all inva...@example.com [...] 28546 SMTP>> STARTTLS 28546 waiting for data on socket 28546 read response data: size=30 28546 SMTP<< 220 2.0.0 Ready to start TLS 28546 initialising GnuTLS as a client on fd 7 28546 GnuTLS global init required. 28546 initialising GnuTLS client session 28546 Expanding various TLS configuration options for session credentials. 28546 TLS: no client certificate specified; okay 28546 TLS: tls_verify_certificates not set or empty, ignoring 28546 GnuTLS using default session cipher/priority "NORMAL" 28546 Setting D-H prime minimum acceptable bits to 512 28546 TLS: server certificate verification not required 28546 gnutls_handshake was successful 28546 cipher: TLS1.0:DHE_RSA_AES_128_CBC_SHA1:128 How did you try to downgrade the tls_dh_min_bits setting and to which value? > Also, is there a debugging > option that would allow me to determine the prime size that the CMU > server is using? You can use gnutls-cli as debugging tool: ametzler@argenau:~$ gnutls-cli -s smtp.srv.cs.cmu.edu -p 25 [...] 220 smtp03.srv.cs.cmu.edu ESMTP Sendmail 8.13.6/8.13.6; Thu, 21 Jun 2012 13:09:17 -0400 (EDT) ehlo foo 250-smtp03.srv.cs.cmu.edu Hello 91-115-38-95.adsl.highway.telekom.at [91.115.38.95], pleased to meet you 250-ENHANCEDSTATUSCODES [...] STARTTLS 220 2.0.0 Ready to start TLS [Press <Ctrl>-D now] *** Starting TLS handshake [...] - Ephemeral Diffie-Hellman parameters - Using prime: 512 bits - Secret key: 511 bits - Peer's public key: 512 bits - Version: TLS1.0 - Key Exchange: DHE-RSA - Cipher: AES-128-CBC - MAC: SHA1 - Compression: NULL [...] cu andreas -- `What a good friend you are to him, Dr. Maturin. His other friends are so grateful to you.' `I sew his ears on from time to time, sure' -- To UNSUBSCRIBE, email to debian-bugs-dist-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org
