diff -up fetchmail-6.3.24/configure.ac.orig fetchmail-6.3.24/configure.ac

--- fetchmail-6.3.24/configure.ac.orig	2012-12-23 16:40:43.000000000 +0100

+++ fetchmail-6.3.24/configure.ac	2017-03-07 12:35:18.961038361 +0100

@@ -803,6 +803,7 @@ fi

 case "$LIBS" in *-lssl*)

 	AC_CHECK_DECLS([SSLv2_client_method],,,[#include <openssl/ssl.h>])

+	AC_CHECK_DECLS([SSLv3_client_method],,,[#include <openssl/ssl.h>])

 	;;

 esac

diff -up fetchmail-6.3.24/fetchmail.c.orig fetchmail-6.3.24/fetchmail.c

--- fetchmail-6.3.24/fetchmail.c.orig	2012-12-14 00:56:41.000000000 +0100

+++ fetchmail-6.3.24/fetchmail.c	2017-03-07 12:35:18.962038368 +0100

@@ -263,6 +263,12 @@ int main(int argc, char **argv)

 #ifdef SSL_ENABLE

 	"+SSL"

 #endif

+#if HAVE_DECL_SSLV2_CLIENT_METHOD + 0 == 0

+ 	"-SSLv2"

+#endif

+#if HAVE_DECL_SSLV3_CLIENT_METHOD + 0 == 0

+ 	"-SSLv3"

+#endif

 #ifdef OPIE_ENABLE

 	"+OPIE"

 #endif /* OPIE_ENABLE */

diff -up fetchmail-6.3.24/fetchmail.h.orig fetchmail-6.3.24/fetchmail.h

--- fetchmail-6.3.24/fetchmail.h.orig	2012-12-14 00:56:41.000000000 +0100

+++ fetchmail-6.3.24/fetchmail.h	2017-03-07 12:35:18.962038368 +0100

@@ -771,9 +771,9 @@ int servport(const char *service);

 int fm_getaddrinfo(const char *node, const char *serv, const struct addrinfo *hints, struct addrinfo **res);

 void fm_freeaddrinfo(struct addrinfo *ai);

-/* prototypes from tls.c */

-int maybe_tls(struct query *ctl);

-int must_tls(struct query *ctl);

+/* prototypes from starttls.c */

+int maybe_starttls(struct query *ctl);

+int must_starttls(struct query *ctl);

 /* prototype from rfc822valid.c */

 int rfc822_valid_msgid(const unsigned char *);

diff -up fetchmail-6.3.24/fetchmail.man.orig fetchmail-6.3.24/fetchmail.man

--- fetchmail-6.3.24/fetchmail.man.orig	2012-12-13 22:50:38.000000000 +0100

+++ fetchmail-6.3.24/fetchmail.man	2017-03-07 12:35:18.968038409 +0100

@@ -412,23 +412,22 @@ from. The folder information is written

 .B \-\-ssl

 (Keyword: ssl)

 .br

-Causes the connection to the mail server to be encrypted

-via SSL.  Connect to the server using the specified base protocol over a

-connection secured by SSL. This option defeats opportunistic starttls

-negotiation. It is highly recommended to use \-\-sslproto 'SSL3'

-\-\-sslcertck to validate the certificates presented by the server and

-defeat the obsolete SSLv2 negotiation. More information is available in

-the \fIREADME.SSL\fP file that ships with fetchmail.

-.IP

-Note that fetchmail may still try to negotiate SSL through starttls even

-if this option is omitted. You can use the \-\-sslproto option to defeat

-this behavior or tell fetchmail to negotiate a particular SSL protocol.

+Causes the connection to the mail server to be encrypted via SSL, by

+negotiating SSL directly after connecting (SSL-wrapped mode).  It is

+highly recommended to use \-\-sslcertck to validate the certificates

+presented by the server.  Please see the description of \-\-sslproto

+below!  More information is available in the \fIREADME.SSL\fP file that

+ships with fetchmail.

+.IP

+Note that even if this option is omitted, fetchmail may still negotiate

+SSL in-band for POP3 or IMAP, through the STLS or STARTTLS feature.  You

+can use the \-\-sslproto option to modify that behavior.

 .IP

 If no port is specified, the connection is attempted to the well known

 port of the SSL version of the base protocol.  This is generally a

 different port than the port used by the base protocol.  For IMAP, this

 is port 143 for the clear protocol and port 993 for the SSL secured

-protocol, for POP3, it is port 110 for the clear text and port 995 for

+protocol; for POP3, it is port 110 for the clear text and port 995 for

 the encrypted variant.

 .IP

 If your system lacks the corresponding entries from /etc/services, see

@@ -470,39 +469,77 @@ cause some complications in daemon mode.

 .IP

 Also see \-\-sslcert above.

 .TP

-.B \-\-sslproto <name>

+.B \-\-sslproto <value>

 (Keyword: sslproto)

 .br

-Forces an SSL/TLS protocol. Possible values are \fB''\fP,

-\&'\fBSSL2\fP' (not supported on all systems),

-\&'\fBSSL23\fP', (use of these two values is discouraged

-and should only be used as a last resort) \&'\fBSSL3\fP', and

-\&'\fBTLS1\fP'.  The default behaviour if this option is unset is: for

-connections without \-\-ssl, use \&'\fBTLS1\fP' so that fetchmail will

-opportunistically try STARTTLS negotiation with TLS1. You can configure

-this option explicitly if the default handshake (TLS1 if \-\-ssl is not

-used) does not work for your server.

-.IP

-Use this option with '\fBTLS1\fP' value to enforce a STARTTLS

-connection. In this mode, it is highly recommended to also use

-\-\-sslcertck (see below).  Note that this will then cause fetchmail

-v6.3.19 to force STARTTLS negotiation even if it is not advertised by

-the server.

-.IP

-To defeat opportunistic TLSv1 negotiation when the server advertises

-STARTTLS or STLS, and use a cleartext connection use \fB''\fP.  This

-option, even if the argument is the empty string, will also suppress the

-diagnostic 'SERVER: opportunistic upgrade to TLS.' message in verbose

-mode. The default is to try appropriate protocols depending on context.

+This option has a dual use, out of historic fetchmail behaviour. It

+controls both the SSL/TLS protocol version and, if \-\-ssl is not

+specified, the STARTTLS behaviour (upgrading the protocol to an SSL or

+TLS connection in-band). Some other options may however make TLS

+mandatory.

+.PP

+Only if this option and \-\-ssl are both missing for a poll, there will

+be opportunistic TLS for POP3 and IMAP, where fetchmail will attempt to

+upgrade to TLSv1 or newer.

+.PP

+Recognized values for \-\-sslproto are given below. You should normally

+chose one of the auto-negotiating options, i. e. '\fBauto\fP' or one of

+the options ending in a plus (\fB+\fP) character. Note that depending

+on OpenSSL library version and configuration, some options cause

+run-time errors because the requested SSL or TLS versions are not

+supported by the particular installed OpenSSL library.

+.RS

+.IP "\fB''\fP, the empty string"

+Disable STARTTLS. If \-\-ssl is given for the same server, log an error

+and pretend that '\fBauto\fP' had been used instead.

+.IP '\fBauto\fP'

+(default). Require TLS. Auto-negotiate TLSv1 or newer, disable SSLv3 downgrade.

+(previous releases of fetchmail have auto-negotiated all protocols that

+their OpenSSL library supported, including the broken SSLv3).

+.IP "\&'\fBSSL23\fP'

+see '\fBauto\fP'.

+.IP \&'\fBSSL2\fP'

+Require SSLv2 exactly. SSLv2 is broken, not supported on all systems, avoid it

+if possible. This will make fetchmail negotiate SSLv2 only, and is the

+only way to have fetchmail permit SSLv2.

+.IP \&'\fBSSL3\fP'

+Require SSLv3 exactly. SSLv3 is broken, not supported on all systems, avoid it

+if possible. This will make fetchmail negotiate SSLv3 only, and is the

+only way besides '\fBSSL3+\fP' to have fetchmail permit SSLv3.

+.IP \&'\fBSSL3+\fP'

+same as '\fBauto\fP', but permit SSLv3 as well. This is the only way

+besides '\fBSSL3\fP' to have fetchmail permit SSLv3.

+.IP \&'\fBTLS1\fP'

+Require TLSv1. This does not negotiate TLSv1.1 or newer, and is

+discouraged. Replace by TLS1+ unless the latter chokes your server.

+.IP \&'\fBTLS1+\fP'

+See '\fBauto\fP'.

+.IP \&'\fBTLS1.1\fP'

+Require TLS v1.1 exactly.

+.IP \&'\fBTLS1.1+\fP'

+Require TLS. Auto-negotiate TLSv1.1 or newer.

+.IP \&'\fBTLS1.2\fP'

+Require TLS v1.2 exactly.

+.IP '\fBTLS1.2+\fP'

+Require TLS. Auto-negotiate TLSv1.2 or newer.

+.IP "Unrecognized parameters"

+are treated the same as '\fBauto\fP'.

+.RE

+.IP

+NOTE: you should hardly ever need to use anything other than '' (to

+force an unencrypted connection) or 'auto' (to enforce TLS).

 .TP

 .B \-\-sslcertck

 (Keyword: sslcertck)

 .br

-Causes fetchmail to strictly check the server certificate against a set of

-local trusted certificates (see the \fBsslcertfile\fP and \fBsslcertpath\fP

-options). If the server certificate cannot be obtained or is not signed by one

-of the trusted ones (directly or indirectly), the SSL connection will fail,

-regardless of the \fBsslfingerprint\fP option.

+Causes fetchmail to require that SSL/TLS be used and disconnect if it

+can not successfully negotiate SSL or TLS, or if it cannot successfully

+verify and validate the certificate and follow it to a trust anchor (or

+trusted root certificate). The trust anchors are given as a set of local

+trusted certificates (see the \fBsslcertfile\fP and \fBsslcertpath\fP

+options). If the server certificate cannot be obtained or is not signed

+by one of the trusted ones (directly or indirectly), fetchmail will

+disconnect, regardless of the \fBsslfingerprint\fP option.

 .IP

 Note that CRL (certificate revocation lists) are only supported in

 OpenSSL 0.9.7 and newer! Your system clock should also be reasonably

@@ -1202,31 +1239,33 @@ capability response. Specify a user opti

 username and the part to the right as the NTLM domain.

 .SS Secure Socket Layers (SSL) and Transport Layer Security (TLS)

+.PP All retrieval protocols can use SSL or TLS wrapping for the

+transport. Additionally, POP3 and IMAP retrival can also negotiate

+SSL/TLS by means of STARTTLS (or STLS).

 .PP

 Note that fetchmail currently uses the OpenSSL library, which is

 severely underdocumented, so failures may occur just because the

 programmers are not aware of OpenSSL's requirement of the day.

 For instance, since v6.3.16, fetchmail calls

 OpenSSL_add_all_algorithms(), which is necessary to support certificates

-with SHA256 on OpenSSL 0.9.8 -- this information is deeply hidden in the

-documentation and not at all obvious.  Please do not hesitate to report

-subtle SSL failures.

-.PP

-You can access SSL encrypted services by specifying the \-\-ssl option.

-You can also do this using the "ssl" user option in the .fetchmailrc

-file. With SSL encryption enabled, queries are initiated over a

-connection after negotiating an SSL session, and the connection fails if

-SSL cannot be negotiated.  Some services, such as POP3 and IMAP, have

+using SHA256 on OpenSSL 0.9.8 -- this information is deeply hidden in

+the documentation and not at all obvious.  Please do not hesitate to

+report subtle SSL failures.

+.PP

+You can access SSL encrypted services by specifying the options starting

+with \-\-ssl, such as \-\-ssl, \-\-sslproto, \-\-sslcertck, and others.

+You can also do this using the corresponding user options in the .fetchmailrc

+file.  Some services, such as POP3 and IMAP, have

 different well known ports defined for the SSL encrypted services.  The

 encrypted ports will be selected automatically when SSL is enabled and

-no explicit port is specified. The \-\-sslproto 'SSL3' option should be

-used to select the SSLv3 protocol (default if unset: v2 or v3).  Also,

-the \-\-sslcertck command line or sslcertck run control file option

-should be used to force strict certificate checking - see below.

+no explicit port is specified.   Also, the \-\-sslcertck command line or

+sslcertck run control file option should be used to force strict

+certificate checking - see below.

 .PP

 If SSL is not configured, fetchmail will usually opportunistically try to use

-STARTTLS. STARTTLS can be enforced by using \-\-sslproto "TLS1". TLS

-connections use the same port as the unencrypted version of the

+STARTTLS. STARTTLS can be enforced by using \-\-sslproto\~auto and

+defeated by using \-\-sslproto\~''.

+TLS connections use the same port as the unencrypted version of the

 protocol and negotiate TLS via special command. The \-\-sslcertck

 command line or sslcertck run control file option should be used to

 force strict certificate checking - see below.

diff -up fetchmail-6.3.24/imap.c.orig fetchmail-6.3.24/imap.c

--- fetchmail-6.3.24/imap.c.orig	2012-12-13 22:12:26.000000000 +0100

+++ fetchmail-6.3.24/imap.c	2017-03-07 12:35:18.962038368 +0100

@@ -405,6 +405,8 @@ static int imap_getauth(int sock, struct

 /* apply for connection authorization */

 {

     int ok = 0;

+    char *commonname;

+

     (void)greeting;

     /*

@@ -429,25 +431,21 @@ static int imap_getauth(int sock, struct

         return(PS_SUCCESS);

     }

-#ifdef SSL_ENABLE

-    if (maybe_tls(ctl)) {

-	char *commonname;

-

-	commonname = ctl->server.pollname;

-	if (ctl->server.via)

-	    commonname = ctl->server.via;

-	if (ctl->sslcommonname)

-	    commonname = ctl->sslcommonname;

+    commonname = ctl->server.pollname;

+    if (ctl->server.via)

+       commonname = ctl->server.via;

+    if (ctl->sslcommonname)

+       commonname = ctl->sslcommonname;

-	if (strstr(capabilities, "STARTTLS")

-		|| must_tls(ctl)) /* if TLS is mandatory, ignore capabilities */

+#ifdef SSL_ENABLE

+    if (maybe_starttls(ctl)) {

+       if ((strstr(capabilities, "STARTTLS") && maybe_starttls(ctl))

+               || must_starttls(ctl)) /* if TLS is mandatory, ignore capabilities */

 	{

-	    /* Use "tls1" rather than ctl->sslproto because tls1 is the only

-	     * protocol that will work with STARTTLS.  Don't need to worry

-	     * whether TLS is mandatory or opportunistic unless SSLOpen() fails

-	     * (see below). */

+	    /* Don't need to worry whether TLS is mandatory or

+	     * opportunistic unless SSLOpen() fails (see below). */

 	    if (gen_transact(sock, "STARTTLS") == PS_SUCCESS

-		    && (set_timeout(mytimeout), SSLOpen(sock, ctl->sslcert, ctl->sslkey, "tls1", ctl->sslcertck,

+		    && (set_timeout(mytimeout), SSLOpen(sock, ctl->sslcert, ctl->sslkey, ctl->sslproto, ctl->sslcertck,

 			ctl->sslcertfile, ctl->sslcertpath, ctl->sslfingerprint, commonname,

 			ctl->server.pollname, &ctl->remotename)) != -1)

 	    {

@@ -470,7 +468,7 @@ static int imap_getauth(int sock, struct

 		{

 		    report(stdout, GT_("%s: upgrade to TLS succeeded.\n"), commonname);

 		}

-	    } else if (must_tls(ctl)) {

+	    } else if (must_starttls(ctl)) {

 		/* Config required TLS but we couldn't guarantee it, so we must

 		 * stop. */

 		set_timeout(0);

@@ -492,6 +490,10 @@ static int imap_getauth(int sock, struct

 		/* Usable.  Proceed with authenticating insecurely. */

 	    }

 	}

+    } else {

+	if (strstr(capabilities, "STARTTLS") && outlevel >= O_VERBOSE) {

+	    report(stdout, GT_("%s: WARNING: server offered STARTTLS but sslproto '' given.\n"), commonname);

+	}

     }

 #endif /* SSL_ENABLE */

diff -up fetchmail-6.3.24/Makefile.am.orig fetchmail-6.3.24/Makefile.am

--- fetchmail-6.3.24/Makefile.am.orig	2012-12-23 16:40:57.000000000 +0100

+++ fetchmail-6.3.24/Makefile.am	2017-03-07 12:35:18.962038368 +0100

@@ -31,7 +31,7 @@ libfm_a_SOURCES=	xmalloc.c base64.c rfc8

 			servport.c ntlm.h smbbyteorder.h smbdes.h smbmd4.h \

 			smbencrypt.h smbdes.c smbencrypt.c smbmd4.c smbutil.c \

 			libesmtp/gethostbyname.h libesmtp/gethostbyname.c \

-			smbtypes.h fm_getaddrinfo.c tls.c rfc822valid.c \

+			smbtypes.h fm_getaddrinfo.c starttls.c rfc822valid.c \

 			xmalloc.h sdump.h sdump.c x509_name_match.c \

 			fm_strl.h md5c.c

 if NTLM_ENABLE

diff -up fetchmail-6.3.24/Makefile.in.orig fetchmail-6.3.24/Makefile.in

--- fetchmail-6.3.24/Makefile.in.orig	2012-12-23 17:29:56.000000000 +0100

+++ fetchmail-6.3.24/Makefile.in	2017-03-07 12:35:18.963038375 +0100

@@ -97,14 +97,14 @@ am__libfm_a_SOURCES_DIST = xmalloc.c bas

 	rfc2047e.c servport.c ntlm.h smbbyteorder.h smbdes.h smbmd4.h \

 	smbencrypt.h smbdes.c smbencrypt.c smbmd4.c smbutil.c \

 	libesmtp/gethostbyname.h libesmtp/gethostbyname.c smbtypes.h \

-	fm_getaddrinfo.c tls.c rfc822valid.c xmalloc.h sdump.h sdump.c \

+	fm_getaddrinfo.c starttls.c rfc822valid.c xmalloc.h sdump.h sdump.c \

 	x509_name_match.c fm_strl.h md5c.c ntlmsubr.c

 @NTLM_ENABLE_TRUE@am__objects_1 = ntlmsubr.$(OBJEXT)

 am_libfm_a_OBJECTS = xmalloc.$(OBJEXT) base64.$(OBJEXT) \

 	rfc822.$(OBJEXT) report.$(OBJEXT) rfc2047e.$(OBJEXT) \

 	servport.$(OBJEXT) smbdes.$(OBJEXT) smbencrypt.$(OBJEXT) \

 	smbmd4.$(OBJEXT) smbutil.$(OBJEXT) gethostbyname.$(OBJEXT) \

-	fm_getaddrinfo.$(OBJEXT) tls.$(OBJEXT) rfc822valid.$(OBJEXT) \

+	fm_getaddrinfo.$(OBJEXT) starttls.$(OBJEXT) rfc822valid.$(OBJEXT) \

 	sdump.$(OBJEXT) x509_name_match.$(OBJEXT) md5c.$(OBJEXT) \

 	$(am__objects_1)

 libfm_a_OBJECTS = $(am_libfm_a_OBJECTS)

@@ -483,7 +483,7 @@ libfm_a_SOURCES = xmalloc.c base64.c rfc

 	servport.c ntlm.h smbbyteorder.h smbdes.h smbmd4.h \

 	smbencrypt.h smbdes.c smbencrypt.c smbmd4.c smbutil.c \

 	libesmtp/gethostbyname.h libesmtp/gethostbyname.c smbtypes.h \

-	fm_getaddrinfo.c tls.c rfc822valid.c xmalloc.h sdump.h sdump.c \

+	fm_getaddrinfo.c starttls.c rfc822valid.c xmalloc.h sdump.h sdump.c \

 	x509_name_match.c fm_strl.h md5c.c $(am__append_1)

 libfm_a_LIBADD = $(EXTRAOBJ)

 libfm_a_DEPENDENCIES = $(EXTRAOBJ)

diff -up fetchmail-6.3.24/NEWS.orig fetchmail-6.3.24/NEWS

--- fetchmail-6.3.24/NEWS.orig	2017-03-07 12:35:18.958038341 +0100

+++ fetchmail-6.3.24/NEWS	2017-03-07 12:35:18.968038409 +0100

@@ -56,6 +56,29 @@ removed from a 6.4.0 or newer release.)

 --------------------------------------------------------------------------------

+## SECURITY FIXES THAT AFFECT BEHAVIOUR AND MAY WANT RECONFIGURATION

+* Fetchmail no longer attempts to negotiate SSLv3 by default,

+  even with --sslproto ssl23. Fetchmail can now use SSLv3, or TLSv1.1 or a newer

+  TLS version, with STLS/STARTTLS (it would previously force TLSv1.0).  If the

+  OpenSSL version used at build and run-time supports these versions, -sslproto

+  ssl3 can be used to enable this specific version.  Doing so is discouraged

+  because these protocols are broken.

+

+  Along the lines suggested - as patch - by Kurt Roeckx, Debian Bug #768843.

+

+  While this change is supposed to be compatible with common configurations,

+  users are advised to change all explicit --sslproto ssl2, --sslproto

+  ssl3, --sslproto tls1 to --sslproto auto, so that they can enable TLSv1.1 and

+  TLSv1.2 on systems with OpenSSL 1.0.1 or newer.

+

+  The --sslproto option now understands the values auto, tls1+, tls1.1+,

+  tls1.2+ (case insensitively).

+

+## CHANGES

+* Fetchmail now supports --sslproto auto and --sslproto tls1+ (same as ssl23).

+* --sslproto tls1.1+ and tls1.2+ are now supported for auto-negotiation with a

+  minimum specified TLS protocol version.

+

 fetchmail-6.3.24 (released 2012-12-23, 26108 LoC):

 # NOTE THAT THE RELEASE OF FUTURE FETCHMAIL 6.3.X VERSIONS IS UNCLEAR.

diff -up fetchmail-6.3.24/pop3.c.orig fetchmail-6.3.24/pop3.c

--- fetchmail-6.3.24/pop3.c.orig	2012-12-13 22:50:38.000000000 +0100

+++ fetchmail-6.3.24/pop3.c	2017-03-07 12:35:18.963038375 +0100

@@ -281,6 +281,7 @@ static int pop3_getauth(int sock, struct

 #endif /* OPIE_ENABLE */

 #ifdef SSL_ENABLE

     flag connection_may_have_tls_errors = FALSE;

+    char *commonname;

 #endif /* SSL_ENABLE */

     done_capa = FALSE;

@@ -393,7 +394,7 @@ static int pop3_getauth(int sock, struct

 		(ctl->server.authenticate == A_KERBEROS_V5) ||

 		(ctl->server.authenticate == A_OTP) ||

 		(ctl->server.authenticate == A_CRAM_MD5) ||

-		maybe_tls(ctl))

+		maybe_starttls(ctl))

 	{

 	    if ((ok = capa_probe(sock)) != PS_SUCCESS)

 		/* we are in STAGE_GETAUTH => failure is PS_AUTHFAIL! */

@@ -406,12 +407,12 @@ static int pop3_getauth(int sock, struct

 		    (ok == PS_SOCKET && !ctl->wehaveauthed))

 		{

 #ifdef SSL_ENABLE

-		    if (must_tls(ctl)) {

+		    if (must_starttls(ctl)) {

 			/* fail with mandatory STLS without repoll */

 			report(stderr, GT_("TLS is mandatory for this session, but server refused CAPA command.\n"));

 			report(stderr, GT_("The CAPA command is however necessary for TLS.\n"));

 			return ok;

-		    } else if (maybe_tls(ctl)) {

+		    } else if (maybe_starttls(ctl)) {

 			/* defeat opportunistic STLS */

 			xfree(ctl->sslproto);

 			ctl->sslproto = xstrdup("");

@@ -431,24 +432,19 @@ static int pop3_getauth(int sock, struct

 	}

 #ifdef SSL_ENABLE

-	if (maybe_tls(ctl)) {

-	    char *commonname;

+	commonname = ctl->server.pollname;

+	if (ctl->server.via)

+	    commonname = ctl->server.via;

+	if (ctl->sslcommonname)

+	   commonname = ctl->sslcommonname;

-	    commonname = ctl->server.pollname;

-	    if (ctl->server.via)

-		commonname = ctl->server.via;

-	    if (ctl->sslcommonname)

-		commonname = ctl->sslcommonname;

-

-	   if (has_stls

-		   || must_tls(ctl)) /* if TLS is mandatory, ignore capabilities */

+	if (maybe_starttls(ctl)) {

+	   if (has_stls || must_starttls(ctl)) /* if TLS is mandatory, ignore capabilities */

 	   {

-	       /* Use "tls1" rather than ctl->sslproto because tls1 is the only

-		* protocol that will work with STARTTLS.  Don't need to worry

-		* whether TLS is mandatory or opportunistic unless SSLOpen() fails

-		* (see below). */

+	       /* Don't need to worry whether TLS is mandatory or

+	        * opportunistic unless SSLOpen() fails (see below). */

 	       if (gen_transact(sock, "STLS") == PS_SUCCESS

-		       && (set_timeout(mytimeout), SSLOpen(sock, ctl->sslcert, ctl->sslkey, "tls1", ctl->sslcertck,

+		       && (set_timeout(mytimeout), SSLOpen(sock, ctl->sslcert, ctl->sslkey, ctl->sslproto, ctl->sslcertck,

 			   ctl->sslcertfile, ctl->sslcertpath, ctl->sslfingerprint, commonname,

 			   ctl->server.pollname, &ctl->remotename)) != -1)

 	       {

@@ -475,7 +471,7 @@ static int pop3_getauth(int sock, struct

 		   {

 		       report(stdout, GT_("%s: upgrade to TLS succeeded.\n"), commonname);

 		   }

-	       } else if (must_tls(ctl)) {

+	       } else if (must_starttls(ctl)) {

 		   /* Config required TLS but we couldn't guarantee it, so we must

 		    * stop. */

 		   set_timeout(0);

@@ -495,7 +491,11 @@ static int pop3_getauth(int sock, struct

 		   }

 	       }

 	   }

-	} /* maybe_tls() */

+	} else { /* maybe_starttls() */

+	    if (has_stls && outlevel >= O_VERBOSE) {

+	        report(stdout, GT_("%s: WARNING: server offered STLS, but sslproto '' given.\n"), commonname);

+	    }

+	} /* maybe_starttls() */

 #endif /* SSL_ENABLE */

 	/*

diff -up fetchmail-6.3.24/README.SSL.orig fetchmail-6.3.24/README.SSL

--- fetchmail-6.3.24/README.SSL.orig	2011-08-16 13:24:53.000000000 +0200

+++ fetchmail-6.3.24/README.SSL	2017-03-07 12:35:18.963038375 +0100

@@ -11,36 +11,48 @@ specific to fetchmail.

 In case of troubles, mail the README.SSL-SERVER file to your ISP and 

 have them check their server configuration against it.

-Unfortunately, fetchmail confuses SSL/TLS protocol levels with whether 

-a service needs to use in-band negotiation (STLS/STARTTLS for POP3/IMAP4) or is 

-totally SSL-wrapped on a separate port.  For compatibility reasons, this cannot 

-be fixed in a bugfix release.

+Unfortunately, fetchmail confuses SSL/TLS protocol levels with whether a

+service needs to use in-band negotiation (STLS/STARTTLS for POP3/IMAP4)

+or is totally SSL-wrapped on a separate port.  For compatibility

+reasons, this cannot be fixed in a bugfix or minor release.

 	-- Matthias Andree, 2009-05-09

+Also, fetchmail 6.4.0 and newer releases (this is also true for this release,

+as the changes were backported from upstream - noted by Red Hat) changed

+some of the semantics as the result of a bug-fix, and will auto-negotiate

+TLSv1 or newer only. If your server does not support this, you may have

+to specify --sslproto ssl3.  This is in order to prefer the newer TLS

+protocols, because SSLv2 and v3 are broken.

+

+       -- Matthias Andree, 2015-01-16

+

 Quickstart

 ----------

+Use an up-to-date release of OpenSSL 1.0.1 or newer, so as to get

+TLSv1.2 support.

+

 For use of SSL or TLS with in-band negotiation on the regular service's port, 

 i. e. with STLS or STARTTLS, use these command line options

-    --sslproto tls1 --sslcertck

+    --sslproto auto --sslcertck

 or these options in the rcfile (after the respective "user"... options)

-      sslproto tls1   sslcertck

+      sslproto auto   sslcertck

 For use of SSL or TLS on a separate port, if the whole TCP connection is 

-SSL-encrypted from the very beginning, use these command line options (in the 

-rcfile, omit all leading "--"):

+SSL-encrypted from the very beginning (SSL- or TLS-wrapped), use these

+command line options (in the rcfile, omit all leading "--"):

-    --ssl --sslproto ssl3 --sslcertck

+    --ssl --sslproto auto --sslcertck

 or these options in the rcfile (after the respective "user"... options)

-      ssl   sslproto ssl3   sslcertck

+      ssl   sslproto auto   sslcertck

 Background and use (long version :-))

diff -up fetchmail-6.3.24/socket.c.orig fetchmail-6.3.24/socket.c

--- fetchmail-6.3.24/socket.c.orig	2012-12-13 23:32:29.000000000 +0100

+++ fetchmail-6.3.24/socket.c	2017-03-07 12:41:24.558502332 +0100

@@ -844,6 +844,9 @@ int SSLOpen(int sock, char *mycert, char

 {

         struct stat randstat;

         int i;

+	/* disable SSLv2 and SSLv3 by default. SSLv2 can be enabled with '--sslproto ssl2'.

+	   SSLv3 can be enabled with '--sslproto ssl3' or '--sslproto ssl3+' */

+        int avoid_ssl_versions = SSL_OP_NO_SSLv2 | SSL_OP_NO_SSLv3;

 	long sslopts = SSL_OP_ALL;

 	SSL_load_error_strings();

@@ -873,28 +876,68 @@ int SSLOpen(int sock, char *mycert, char

 	/* Make sure a connection referring to an older context is not left */

 	_ssl_context[sock] = NULL;

-	if(myproto) {

-		if(!strcasecmp("ssl2",myproto)) {

+        if(myproto) {

+                if(!strcasecmp("ssl2",myproto)) {

 #if HAVE_DECL_SSLV2_CLIENT_METHOD + 0 > 0

-			_ctx[sock] = SSL_CTX_new(SSLv2_client_method());

+                        _ctx[sock] = SSL_CTX_new(SSLv2_client_method());

 #else

-			report(stderr, GT_("Your operating system does not support SSLv2.\n"));

-			return -1;

+                        report(stderr, GT_("Your OpenSSL version does not support SSLv2.\n"));

+                        return -1;

 #endif

-		} else if(!strcasecmp("ssl3",myproto)) {

-			_ctx[sock] = SSL_CTX_new(SSLv3_client_method());

-		} else if(!strcasecmp("tls1",myproto)) {

-			_ctx[sock] = SSL_CTX_new(TLSv1_client_method());

-		} else if (!strcasecmp("ssl23",myproto)) {

-			myproto = NULL;

-		} else {

-			fprintf(stderr,GT_("Invalid SSL protocol '%s' specified, using default (SSLv23).\n"), myproto);

-			myproto = NULL;

-		}

-	}

-	if(!myproto) {

-		_ctx[sock] = SSL_CTX_new(SSLv23_client_method());

-	}

+                        avoid_ssl_versions &= ~SSL_OP_NO_SSLv2;

+                } else if(!strcasecmp("ssl3",myproto)) {

+#if HAVE_DECL_SSLV3_CLIENT_METHOD + 0 > 0

+                        _ctx[sock] = SSL_CTX_new(SSLv3_client_method());

+#else

+                        report(stderr, GT_("Your OpenSSL version does not support SSLv3.\n"));

+                        return -1;

+#endif

+                        avoid_ssl_versions &= ~SSL_OP_NO_SSLv3;

+                } else if(!strcasecmp("ssl3+",myproto)) {

+                        avoid_ssl_versions &= ~SSL_OP_NO_SSLv3;

+                        myproto = NULL;

+                } else if(!strcasecmp("tls1",myproto)) {

+                        _ctx[sock] = SSL_CTX_new(TLSv1_client_method());

+                } else if(!strcasecmp("tls1+",myproto)) {

+                        myproto = NULL;

+#if defined(TLS1_1_VERSION) && TLS_MAX_VERSION >= TLS1_1_VERSION

+                } else if(!strcasecmp("tls1.1",myproto)) {

+                        _ctx[sock] = SSL_CTX_new(TLSv1_1_client_method());

+                } else if(!strcasecmp("tls1.1+",myproto)) {

+                        myproto = NULL;

+                        avoid_ssl_versions |= SSL_OP_NO_TLSv1;

+#else

+                } else if(!strcasecmp("tls1.1",myproto) || !strcasecmp("tls1.1+", myproto)) {

+                        report(stderr, GT_("Your OpenSSL version does not support TLS v1.1.\n"));

+                        return -1;

+#endif

+#if defined(TLS1_2_VERSION) && TLS_MAX_VERSION >= TLS1_2_VERSION

+                } else if(!strcasecmp("tls1.2",myproto)) {

+                        _ctx[sock] = SSL_CTX_new(TLSv1_2_client_method());

+                } else if(!strcasecmp("tls1.2+",myproto)) {

+                        myproto = NULL;

+                        avoid_ssl_versions |= SSL_OP_NO_TLSv1;

+                        avoid_ssl_versions |= SSL_OP_NO_TLSv1_1;

+#else

+                } else if(!strcasecmp("tls1.2",myproto) || !strcasecmp("tls1.2+", myproto)) {

+                        report(stderr, GT_("Your OpenSSL version does not support TLS v1.2.\n"));

+                        return -1;

+#endif

+                } else if (!strcasecmp("ssl23",myproto) || 0 == strcasecmp("auto",myproto)) {

+                        myproto = NULL;

+                } else {

+                        report(stderr,GT_("Invalid SSL protocol '%s' specified, using default autoselect (SSL23).\n"), myproto);

+                        myproto = NULL;

+                }

+        }

+        // do not combine into an else { } as myproto may be nulled

+        // above!

+        if(!myproto) {

+                // SSLv23 is a misnomer and will in fact use the best

+                // available protocol, subject to SSL_OP_NO*

+                // constraints.

+                _ctx[sock] = SSL_CTX_new(SSLv23_client_method());

+        }

 	if(_ctx[sock] == NULL) {

 		ERR_print_errors_fp(stderr);

 		return(-1);

@@ -906,7 +949,7 @@ int SSLOpen(int sock, char *mycert, char

 		sslopts &= ~ SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS;

 	}

-	SSL_CTX_set_options(_ctx[sock], sslopts);

+	SSL_CTX_set_options(_ctx[sock], sslopts | avoid_ssl_versions);

 	if (certck) {

 		SSL_CTX_set_verify(_ctx[sock], SSL_VERIFY_PEER, SSL_ck_verify_callback);

@@ -985,6 +1028,24 @@ int SSLOpen(int sock, char *mycert, char

 		return(-1);

 	}

+	if (outlevel >= O_VERBOSE) {

+	    SSL_CIPHER const *sc;

+	    int bitsmax, bitsused;

+

+	    const char *ver;

+

+	    ver = SSL_get_version(_ssl_context[sock]);

+

+	    sc = SSL_get_current_cipher(_ssl_context[sock]);

+	    if (!sc) {

+		report (stderr, GT_("Cannot obtain current SSL/TLS cipher - no session established?\n"));

+	    } else {

+		bitsused = SSL_CIPHER_get_bits(sc, &bitsmax);

+		report(stdout, GT_("SSL/TLS: using protocol %s, cipher %s, %d/%d secret/processed bits\n"),

+		    ver, SSL_CIPHER_get_name(sc), bitsused, bitsmax);

+		}

+	}

+

 	/* Paranoia: was the callback not called as we expected? */

 	if (!_depth0ck) {

 		report(stderr, GT_("Certificate/fingerprint verification was somehow skipped!\n"));

diff -up fetchmail-6.3.24/starttls.c.orig fetchmail-6.3.24/starttls.c

--- fetchmail-6.3.24/starttls.c.orig	2017-03-07 12:35:18.964038382 +0100

+++ fetchmail-6.3.24/starttls.c	2017-03-07 12:35:18.964038382 +0100

@@ -0,0 +1,37 @@

+/** \file tls.c - collect common TLS functionality

+ * \author Matthias Andree

+ * \date 2006

+ */

+

+#include "fetchmail.h"

+

+#include <string.h>

+

+#ifdef HAVE_STRINGS_H

+#include <strings.h>

+#endif

+

+/** return true if user allowed opportunistic STARTTLS/STLS */

+int maybe_starttls(struct query *ctl) {

+#ifdef SSL_ENABLE

+         /* opportunistic  or forced TLS */

+    return (!ctl->sslproto || strlen(ctl->sslproto))

+	&& !ctl->use_ssl;

+#else

+    (void)ctl;

+    return 0;

+#endif

+}

+

+/** return true if user requires STARTTLS/STLS, note though that this

+ * code must always use a logical AND with maybe_tls(). */

+int must_starttls(struct query *ctl) {

+#ifdef SSL_ENABLE

+    return maybe_starttls(ctl)

+	&& (ctl->sslfingerprint || ctl->sslcertck

+		|| (ctl->sslproto && !strcasecmp(ctl->sslproto, "tls1")));

+#else

+    (void)ctl;

+    return 0;

+#endif

+}

diff -up fetchmail-6.3.24/tls.c.orig fetchmail-6.3.24/tls.c

--- fetchmail-6.3.24/tls.c.orig	2012-12-13 22:12:27.000000000 +0100

+++ fetchmail-6.3.24/tls.c	2017-03-07 12:35:18.964038382 +0100

@@ -1,35 +0,0 @@

-/** \file tls.c - collect common TLS functionality 

- * \author Matthias Andree

- * \date 2006

- */

-

-#include "fetchmail.h"