Clarify request of client certificates. This is a FAQ.

[openssl.git] / FAQ

diff --git a/FAQ b/FAQ
index a45c545bf6d731d41f70f88fe60e0527e438698a..019c016bebcacdf6d3c36b37fb86117042d08a1d 100644 (file)
--- a/FAQ
+++ b/FAQ
@@ -25,6 +25,7 @@ OpenSSL  -  Frequently Asked Questions
 * Why can't I make an SSL connection using a DSA certificate?
 * How can I remove the passphrase on a private key?
 * Why can't I use OpenSSL certificates with SSL client authentication?
 * Why can't I make an SSL connection using a DSA certificate?
 * How can I remove the passphrase on a private key?
 * Why can't I use OpenSSL certificates with SSL client authentication?

+* Why does my browser give a warning about a mismatched hostname?

 
 [BUILD] Questions about building and testing OpenSSL
 
 
 [BUILD] Questions about building and testing OpenSSL
 


@@ -46,6 +47,7 @@ OpenSSL  -  Frequently Asked Questions
 * Why do I get errors about unknown algorithms?
 * Why can't the OpenSSH configure script detect OpenSSL?
 * Can I use OpenSSL's SSL library with non-blocking I/O?
 * Why do I get errors about unknown algorithms?
 * Why can't the OpenSSH configure script detect OpenSSL?
 * Can I use OpenSSL's SSL library with non-blocking I/O?

+* Why doesn't my server application receive a client certificate?

 
 ===============================================================================
 
 
 ===============================================================================
 


@@ -54,7 +56,7 @@ OpenSSL  -  Frequently Asked Questions
 * Which is the current version of OpenSSL?
 
 The current version is available from <URL: http://www.openssl.org>.
 * Which is the current version of OpenSSL?
 
 The current version is available from <URL: http://www.openssl.org>.

-OpenSSL 0.9.6 was released on September 24th, 2000.
+OpenSSL 0.9.6a was released on April 5th, 2001.

 
 In addition to the current stable release, you can also access daily
 snapshots of the OpenSSL development version at <URL:
 
 In addition to the current stable release, you can also access daily
 snapshots of the OpenSSL development version at <URL:


@@ -115,17 +117,8 @@ A number of Linux and *BSD distributions include OpenSSL.
 
 * Why aren't tools like 'autoconf' and 'libtool' used?
 
 
 * Why aren't tools like 'autoconf' and 'libtool' used?
 

-autoconf is a nice tool, but is unfortunately very Unix-centric.
-Although one can come up with solution to have ports keep in track,
-there's also some work needed for that, and can be quite painful at
-times.  If there was a 'autoconf'-like tool that generated perl
-scripts or something similarly general, it would probably be used
-in OpenSSL much earlier.
-
-libtool has repeatadly been reported by some members of the OpenSSL
-development and others to be a pain to use.  So far, those in the
-development team who have said anything about this have expressed
-a wish to avoid libtool for that reason.
+autoconf will probably be used in future OpenSSL versions. If it was
+less Unix-centric, it might have been used much earlier.

 
 
 [LEGAL] =======================================================================
 
 
 [LEGAL] =======================================================================


@@ -177,18 +170,22 @@ application you are using.  It is likely that it never worked
 correctly.  OpenSSL 0.9.5 and later make the error visible by refusing
 to perform potentially insecure encryption.
 
 correctly.  OpenSSL 0.9.5 and later make the error visible by refusing
 to perform potentially insecure encryption.
 

-On systems without /dev/urandom, it is a good idea to use the Entropy
-Gathering Demon; see the RAND_egd() manpage for details.
+On systems without /dev/urandom and /dev/random, it is a good idea to
+use the Entropy Gathering Demon (EGD); see the RAND_egd() manpage for
+details.  Starting with version 0.9.7, OpenSSL will automatically look
+for an EGD socket at /var/run/egd-pool, /dev/egd-pool, /etc/egd-pool and
+/etc/entropy.

 
 Most components of the openssl command line tool try to use the
 file $HOME/.rnd (or $RANDFILE, if this environment variable is set)
 for seeding the PRNG.  If this file does not exist or is too short,
 the "PRNG not seeded" error message may occur.
 
 Most components of the openssl command line tool try to use the
 file $HOME/.rnd (or $RANDFILE, if this environment variable is set)
 for seeding the PRNG.  If this file does not exist or is too short,
 the "PRNG not seeded" error message may occur.

-
-[Note to OpenSSL 0.9.5 users: The command "openssl rsa" in version
-0.9.5 does not do this and will fail on systems without /dev/urandom
-when trying to password-encrypt an RSA key!  This is a bug in the
-library; try a later version instead.]
+Pointing $RANDFILE to an Entropy Gathering Daemon socket does not work.
+Use the "-rand" option of the OpenSSL command line tools instead.
+The $RANDFILE environment variable and $HOME/.rnd are only used by the
+OpenSSL command line tools. Applications using the OpenSSL library
+provide their own configuration options to specify the entropy source,
+please check out the documentation coming the with application.

 
 For Solaris 2.6, Tim Nibbe <tnibbe@sprint.net> and others have suggested
 installing the SUNski package from Sun patch 105710-01 (Sparc) which
 
 For Solaris 2.6, Tim Nibbe <tnibbe@sprint.net> and others have suggested
 installing the SUNski package from Sun patch 105710-01 (Sparc) which


@@ -277,7 +274,7 @@ print out the servers list of acceptable CAs using the OpenSSL s_client tool:
 
 openssl s_client -connect www.some.host:443 -prexit
 
 
 openssl s_client -connect www.some.host:443 -prexit
 

-if your server only requests certificates on certain URLs then you may need
+If your server only requests certificates on certain URLs then you may need

 to manually issue an HTTP GET command to get the list when s_client connects:
 
 GET /some/page/needing/a/certificate.html
 to manually issue an HTTP GET command to get the list when s_client connects:
 
 GET /some/page/needing/a/certificate.html


@@ -325,12 +322,13 @@ tests, get GNU bc from ftp://ftp.gnu.org or from your OS distributor.
 
 * Why does the OpenSSL test fail with "bc: 1 no implemented"?
 
 
 * Why does the OpenSSL test fail with "bc: 1 no implemented"?
 

-On some SCO installations or versions, bc has a bug that gets triggered when
-you run the test suite (using "make test").  The message returned is "bc:
-1 not implemented".  The best way to deal with this is to find another
-implementation of bc and compile/install it.  For example, GNU bc (see
-http://www.gnu.org/software/software.html for download instructions) can
-be safely used.
+On some SCO installations or versions, bc has a bug that gets triggered
+when you run the test suite (using "make test").  The message returned is
+"bc: 1 not implemented".
+
+The best way to deal with this is to find another implementation of bc
+and compile/install it.  GNU bc (see http://www.gnu.org/software/software.html
+for download instructions) can be safely used, for example.

 
 
 * Why does the OpenSSL compilation fail on Alpha True64 Unix?
 
 
 * Why does the OpenSSL compilation fail on Alpha True64 Unix?


@@ -497,44 +495,16 @@ OpenSSL_add_all_algorithms(). See the manual page for more information.
 
 * Why can't the OpenSSH configure script detect OpenSSL?
 
 
 * Why can't the OpenSSH configure script detect OpenSSL?
 

-There is a problem with OpenSSH 1.2.2p1, in that the configure script
-can't find the installed OpenSSL libraries.  The problem is actually
-a small glitch that is easily solved with the following patch to be
-applied to the OpenSSH distribution:
-
------ snip:start -----
---- openssh-1.2.2p1/configure.in.orig  Thu Mar 23 18:56:58 2000
-+++ openssh-1.2.2p1/configure.in       Thu Mar 23 18:55:05 2000
-@@ -152,10 +152,10 @@
- AC_MSG_CHECKING([for OpenSSL/SSLeay directory])
- for ssldir in "" $tryssldir /usr /usr/local/openssl /usr/lib/openssl /usr/local/ssl /usr/lib/ssl /usr/local /usr/pkg /opt /opt/openssl ; do
-       if test ! -z "$ssldir" ; then
--              LIBS="$saved_LIBS -L$ssldir"
-+              LIBS="$saved_LIBS -L$ssldir/lib"
-               CFLAGS="$CFLAGS -I$ssldir/include"
-               if test "x$need_dash_r" = "x1" ; then
--                      LIBS="$LIBS -R$ssldir"
-+                      LIBS="$LIBS -R$ssldir/lib"
-               fi
-       fi
-       LIBS="$LIBS -lcrypto"
---- openssh-1.2.2p1/configure.orig     Thu Mar 23 18:55:02 2000
-+++ openssh-1.2.2p1/configure  Thu Mar 23 18:57:08 2000
-@@ -1890,10 +1890,10 @@
- echo "configure:1891: checking for OpenSSL/SSLeay directory" >&5
- for ssldir in "" $tryssldir /usr /usr/local/openssl /usr/lib/openssl /usr/local/ssl /usr/lib/ssl /usr/local /usr/pkg /opt /opt/openssl ; do
-       if test ! -z "$ssldir" ; then
--              LIBS="$saved_LIBS -L$ssldir"
-+              LIBS="$saved_LIBS -L$ssldir/lib"
-               CFLAGS="$CFLAGS -I$ssldir/include"
-               if test "x$need_dash_r" = "x1" ; then
--                      LIBS="$LIBS -R$ssldir"
-+                      LIBS="$LIBS -R$ssldir/lib"
-               fi
-       fi
-       LIBS="$LIBS -lcrypto"
------ snip:end -----
+Several reasons for problems with the automatic detection exist.
+OpenSSH requires at least version 0.9.5a of the OpenSSL libraries.
+Sometimes the distribution has installed an older version in the system
+locations that is detected instead of a new one installed. The OpenSSL
+library might have been compiled for another CPU or another mode (32/64 bits).
+Permissions might be wrong.

 
 

+The general answer is to check the config.log file generated when running
+the OpenSSH configure script. It should contain the detailed information
+on why the OpenSSL library was not detected or considered incompatible.

 
 * Can I use OpenSSL's SSL library with non-blocking I/O?
 
 
 * Can I use OpenSSL's SSL library with non-blocking I/O?
 


@@ -550,5 +520,12 @@ requiring a bi-directional message exchange; both SSL_read() and
 SSL_write() will try to continue any pending handshake.
 
 
 SSL_write() will try to continue any pending handshake.
 
 

+* Why doesn't my server application receive a client certificate?
+
+Due to the TLS protocol definition, a client will only send a certificate,
+if explicitely asked by the server. Use the SSL_VERIFY_PEER flag of the
+SSL_CTX_set_verify() function to enable the use of client certificates.
+
+

 ===============================================================================
 
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