Diffstat (limited to 'doc/apps/s_client.pod')
1 files changed, 13 insertions, 3 deletions
diff --git a/doc/apps/s_client.pod b/doc/apps/s_client.pod
index 4ebf7b585474..3215b2e8c96f 100644
@@ -10,6 +10,7 @@ s_client - SSL/TLS client program
@@ -90,6 +91,11 @@ Currently the verify operation continues after errors so all the problems
with a certificate chain can be seen. As a side effect the connection
will never fail due to a server certificate verify failure.
+Return verification errors instead of continuing. This will typically
+abort the handshake with a fatal error.
=item B<-CApath directory>
The directory to use for server certificate verification. This directory
@@ -286,6 +292,13 @@ Since the SSLv23 client hello cannot include compression methods or extensions
these will only be supported if its use is disabled, for example by using the
+The B<s_client> utility is a test tool and is designed to continue the
+handshake after any certificate verification errors. As a result it will
+accept any certificate chain (trusted or not) sent by the peer. None test
+applications should B<not> do this as it makes them vulnerable to a MITM
+attack. This behaviour can be changed by with the B<-verify_return_error>
+option: any verify errors are then returned aborting the handshake.
Because this program has a lot of options and also because some of
@@ -293,9 +306,6 @@ the techniques used are rather old, the C source of s_client is rather
hard to read and not a model of how things should be done. A typical
SSL client program would be much simpler.
-The B<-verify> option should really exit if the server verification
The B<-prexit> option is a bit of a hack. We should really report
information whenever a session is renegotiated.