167 lines
5.6 KiB
Text
167 lines
5.6 KiB
Text
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=pod
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=head1 NAME
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s_time - SSL/TLS performance timing program
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=head1 SYNOPSIS
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B<openssl> B<s_time>
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[B<-connect host:port>]
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[B<-www page>]
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[B<-cert filename>]
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[B<-key filename>]
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[B<-CApath directory>]
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[B<-CAfile filename>]
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[B<-reuse>]
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[B<-new>]
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[B<-verify depth>]
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[B<-nbio>]
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[B<-time seconds>]
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[B<-ssl2>]
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[B<-ssl3>]
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[B<-bugs>]
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[B<-cipher cipherlist>]
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=head1 DESCRIPTION
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The B<s_client> command implements a generic SSL/TLS client which connects to a
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remote host using SSL/TLS. It can request a page from the server and includes
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the time to transfer the payload data in its timing measurements. It measures
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the number of connections within a given timeframe, the amount of data
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transferred (if any), and calculates the average time spent for one connection.
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=head1 OPTIONS
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=over 4
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=item B<-connect host:port>
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This specifies the host and optional port to connect to.
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=item B<-www page>
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This specifies the page to GET from the server. A value of '/' gets the
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index.htm[l] page. If this parameter is not specified, then B<s_time> will only
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perform the handshake to establish SSL connections but not transfer any
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payload data.
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=item B<-cert certname>
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The certificate to use, if one is requested by the server. The default is
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not to use a certificate. The file is in PEM format.
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=item B<-key keyfile>
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The private key to use. If not specified then the certificate file will
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be used. The file is in PEM format.
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=item B<-verify depth>
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The verify depth to use. This specifies the maximum length of the
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server certificate chain and turns on server certificate verification.
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Currently the verify operation continues after errors so all the problems
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with a certificate chain can be seen. As a side effect the connection
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will never fail due to a server certificate verify failure.
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=item B<-CApath directory>
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The directory to use for server certificate verification. This directory
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must be in "hash format", see B<verify> for more information. These are
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also used when building the client certificate chain.
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=item B<-CAfile file>
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A file containing trusted certificates to use during server authentication
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and to use when attempting to build the client certificate chain.
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=item B<-new>
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performs the timing test using a new session ID for each connection.
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If neither B<-new> nor B<-reuse> are specified, they are both on by default
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and executed in sequence.
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=item B<-reuse>
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performs the timing test using the same session ID; this can be used as a test
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that session caching is working. If neither B<-new> nor B<-reuse> are
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specified, they are both on by default and executed in sequence.
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=item B<-nbio>
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turns on non-blocking I/O.
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=item B<-ssl2>, B<-ssl3>
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these options disable the use of certain SSL or TLS protocols. By default
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the initial handshake uses a method which should be compatible with all
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servers and permit them to use SSL v3, SSL v2 or TLS as appropriate.
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The timing program is not as rich in options to turn protocols on and off as
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the L<s_client(1)|s_client(1)> program and may not connect to all servers.
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Unfortunately there are a lot of ancient and broken servers in use which
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cannot handle this technique and will fail to connect. Some servers only
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work if TLS is turned off with the B<-ssl3> option; others
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will only support SSL v2 and may need the B<-ssl2> option.
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=item B<-bugs>
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there are several known bug in SSL and TLS implementations. Adding this
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option enables various workarounds.
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=item B<-cipher cipherlist>
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this allows the cipher list sent by the client to be modified. Although
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the server determines which cipher suite is used it should take the first
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supported cipher in the list sent by the client.
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See the L<ciphers(1)|ciphers(1)> command for more information.
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=back
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=head1 NOTES
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B<s_client> can be used to measure the performance of an SSL connection.
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To connect to an SSL HTTP server and get the default page the command
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openssl s_time -connect servername:443 -www / -CApath yourdir -CAfile yourfile.pem -cipher commoncipher [-ssl3]
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would typically be used (https uses port 443). 'commoncipher' is a cipher to
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which both client and server can agree, see the L<cipher(1)|cipher(1)> command
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for details.
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If the handshake fails then there are several possible causes, if it is
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nothing obvious like no client certificate then the B<-bugs>, B<-ssl2>,
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B<-ssl3> options can be tried
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in case it is a buggy server. In particular you should play with these
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options B<before> submitting a bug report to an OpenSSL mailing list.
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A frequent problem when attempting to get client certificates working
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is that a web client complains it has no certificates or gives an empty
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list to choose from. This is normally because the server is not sending
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the clients certificate authority in its "acceptable CA list" when it
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requests a certificate. By using L<s_client(1)|s_client(1)> the CA list can be
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viewed and checked. However some servers only request client authentication
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after a specific URL is requested. To obtain the list in this case it
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is necessary to use the B<-prexit> option of L<s_client(1)|s_client(1)> and
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send an HTTP request for an appropriate page.
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If a certificate is specified on the command line using the B<-cert>
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option it will not be used unless the server specifically requests
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a client certificate. Therefor merely including a client certificate
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on the command line is no guarantee that the certificate works.
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=head1 BUGS
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Because this program does not have all the options of the
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L<s_client(1)|s_client(1)> program to turn protocols on and off, you may not be
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able to measure the performance of all protocols with all servers.
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The B<-verify> option should really exit if the server verification
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fails.
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=head1 SEE ALSO
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L<s_client(1)|s_client(1)>, L<s_server(1)|s_server(1)>, L<ciphers(1)|ciphers(1)>
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=cut
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