Re: [exim] Cutthrough TLS bug

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Author: Mike Cardwell
Date:  
To: exim-users
Subject: Re: [exim] Cutthrough TLS bug
* on the Wed, Oct 30, 2013 at 12:23:47PM +0000, Mike Cardwell wrote:

> In my remote_smtp transport I have:
>
> hosts_require_tls = <; fc00:beef:beef:601:9530:2068:3df9:5cb7
>
> I just added this to the top of my rcpt ACL:
>
> warn control = cutthrough_delivery
>
> Now I'm getting this in my mainlog whenever a message is delivered:
>
> 2013-10-30 12:16:18 a TLS session is required for hype.glue.grepular.com [fc00:beef:beef:601:9530:2068:3df9:5cb7], but an attempt to start TLS failed
>
> The message *is* delivered using a TLS secured connection though:
>
> 2013-10-30 12:16:20 1VbUh8-0006Mc-Po => mike.cardwell@??? P=<mike@???> R=relay_remote T=remote_smtp S=758 H=hype.glue.grepular.com [fc00:beef:beef:601:9530:2068:3df9:5cb7]:25 X=TLSv1.2:DHE-RSA-AES256-GCM-SHA384:256 CV=no DN="/description=TN8sb87Rblzkc66S/C=GB/CN=glue.grepular.com/emailAddress=postmaster@???" C="250 OK id=1VbUhz-0008Cg-3H"


To add to this, I see no errors in the mainlog of the destination server
(glue), and a tcpdump shows that this is what happens during the
cut-through delivery attempt:

<= 220-glue.grepular.com ESMTP Exim 5.99 Wed, 30 Oct 2013 12:28:38 +0000
<= 220 BOOSH
=> EHLO flan.grepular.com
<= 250-SIZE 52428800
<= 250-8BITMIME
<= 250-ETRN
<= 250-PIPELINING
<= 250-STARTTLS
<= 250-PRDR
<= 250 HELP
=> QUIT
<= 221 glue.grepular.com closing connection

It connects, sends an EHLO, sends a QUIT, and then disconnects.

Here's my exim -bV:

Exim version 4.82_RC5 #2 built 27-Oct-2013 19:43:24
Copyright (c) University of Cambridge, 1995 - 2013
(c) The Exim Maintainers and contributors in ACKNOWLEDGMENTS file, 2007 - 2013
Berkeley DB: Berkeley DB 5.1.29: (October 25, 2011)
Support for: crypteq iconv() IPv6 PAM Perl Expand_dlfunc OpenSSL move_frozen_messages Content_Scanning DKIM Old_Demime Experimental_SPF Experimental_DCC Experimental_DMARC Experimental_OCSP Experimental_PRDR Experimental_TPDA Experimental_Redis
Lookups (built-in): lsearch wildlsearch nwildlsearch iplsearch cdb dbm dbmjz dbmnz dnsdb dsearch ldap ldapdn ldapm mysql nis nis0 passwd pgsql sqlite
Authenticators: cram_md5 cyrus_sasl dovecot plaintext spa
Routers: accept dnslookup ipliteral iplookup manualroute queryprogram redirect
Transports: appendfile/maildir/mailstore/mbx autoreply lmtp pipe smtp
Fixed never_users: 0
Size of off_t: 8
Configuration file is /etc/exim4/exim4.conf

-- 
Mike Cardwell  https://grepular.com/     http://cardwellit.com/
OpenPGP Key    35BC AF1D 3AA2 1F84 3DC3  B0CF 70A5 F512 0018 461F
XMPP OTR Key   8924 B06A 7917 AAF3 DBB1  BF1B 295C 3C78 3EF1 46B4