From f82596346bd5fbf5f4e3ace44f73569b8016552c Mon Sep 17 00:00:00 2001 From: "Dr. Stephen Henson" Date: Mon, 7 Apr 2014 13:02:10 +0100 Subject: [PATCH] Document -verify_return_error option. (cherry picked from commit 4e6c12f3088d3ee5747ec9e16d03fc671b8f40be) --- doc/apps/s_client.pod | 16 +++++++++++++--- 1 file changed, 13 insertions(+), 3 deletions(-) diff --git a/doc/apps/s_client.pod b/doc/apps/s_client.pod index 4ebf7b5854..3215b2e8c9 100644 --- a/doc/apps/s_client.pod +++ b/doc/apps/s_client.pod @@ -10,6 +10,7 @@ s_client - SSL/TLS client program B B [B<-connect host:port>] [B<-verify depth>] +[B<-verify_return_error>] [B<-cert filename>] [B<-certform DER|PEM>] [B<-key filename>] @@ -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. +=item B<-verify_return_error> + +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 B<-no_sslv2> option. +The B 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 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. + =head1 BUGS 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 -fails. - The B<-prexit> option is a bit of a hack. We should really report information whenever a session is renegotiated. -- 2.25.1