MFC: Add a quick (?) note for users who may be having sendmail interoperability issues

     due to the recent (FreeBSD-SA-15:10.openssl) OpenSSL change to reject 512 bit
     DH parameters.  Affects 11-CURRENT and 10-STABLE.

1 files changed, 24 insertions, 0 deletions

diff --git a/UPDATING b/UPDATING
index f76d504..e311ea8 100644
--- a/UPDATING
+++ b/UPDATING
@@ -16,6 +16,30 @@ from older versions of FreeBSD, try WITHOUT_CLANG to bootstrap to the tip of
 stable/10, and then rebuild without this option. The bootstrap process from
 older version of current is a bit fragile.
 
+20150614:
+	The import of openssl to address the FreeBSD-SA-15:10.openssl
+	security advisory includes a change which rejects handshakes
+	with DH parameters below 768 bits.  sendmail releases prior
+	to 8.15.2 (not yet released), defaulted to a 512 bit
+	DH parameter setting for client connections.  To work around
+	this interoperability, sendmail can be configured to use a
+	2048 bit DH parameter by:
+
+	1. Edit /etc/mail/`hostname`.mc 
+	2. If a setting for confDH_PARAMETERS does not exist or
+	   exists and is set to a string beginning with '5',
+	   replace it with '2'.
+	3. If a setting for confDH_PARAMETERS exists and is set to
+	   a file path, create a new file with:
+		openssl dhparam -out /path/to/file 2048
+	4. Rebuild the .cf file:
+		cd /etc/mail/; make; make install
+	5. Restart sendmail:
+		cd /etc/mail/; make restart
+
+	A sendmail patch is coming, at which time this file will be
+	updated.
+
 20150601:
 	chmod, chflags, chown and chgrp now affect symlinks in -R mode as
 	defined in symlink(7); previously symlinks were silently ignored.