Ubuntu Manpage: s_time - SSL/TLS performance timing program

Provided by: openssl_1.0.1f-1ubuntu2.27_amd64

NAME

       s_time - SSL/TLS performance timing program

SYNOPSIS

       openssl s_time [-connect host:port] [-www page] [-cert filename] [-key filename] [-CApath directory]
       [-CAfile filename] [-reuse] [-new] [-verify depth] [-nbio] [-time seconds] [-ssl2] [-ssl3] [-bugs]
       [-cipher cipherlist]

DESCRIPTION

       The s_client command implements a generic SSL/TLS client which connects to a remote host using SSL/TLS.
       It can request a page from the server and includes the time to transfer the payload data in its timing
       measurements. It measures the number of connections within a given timeframe, the amount of data
       transferred (if any), and calculates the average time spent for one connection.

OPTIONS

-connect host:port
This specifies the host and optional port to connect to.

-www page
This specifies the page to GET from the server. A value of '/' gets the index.htm[l] page. If this
parameter is not specified, then s_time will only perform the handshake to establish SSL connections
but not transfer any payload data.

-cert certname
The certificate to use, if one is requested by the server. The default is not to use a certificate.
The file is in PEM format.

-key keyfile
The private key to use. If not specified then the certificate file will be used. The file is in PEM
format.

-verify depth
The verify depth to use. This specifies the maximum length of the server certificate chain and turns
on server certificate verification. 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.

-CApath directory
The directory to use for server certificate verification. This directory must be in "hash format",
see verify for more information. These are also used when building the client certificate chain.

-CAfile file
A file containing trusted certificates to use during server authentication and to use when attempting
to build the client certificate chain.

-new
performs the timing test using a new session ID for each connection. If neither -new nor -reuse are
specified, they are both on by default and executed in sequence.

-reuse
performs the timing test using the same session ID; this can be used as a test that session caching
is working. If neither -new nor -reuse are specified, they are both on by default and executed in
sequence.

-nbio
turns on non-blocking I/O.

-ssl2, -ssl3
these options disable the use of certain SSL or TLS protocols. By default the initial handshake uses
a method which should be compatible with all servers and permit them to use SSL v3, SSL v2 or TLS as
appropriate. The timing program is not as rich in options to turn protocols on and off as the
s_client(1) program and may not connect to all servers.

Unfortunately there are a lot of ancient and broken servers in use which cannot handle this technique
and will fail to connect. Some servers only work if TLS is turned off with the -ssl3 option; others
will only support SSL v2 and may need the -ssl2 option.

-bugs
there are several known bug in SSL and TLS implementations. Adding this option enables various
workarounds.

-cipher cipherlist
this allows the cipher list sent by the client to be modified. Although the server determines which
cipher suite is used it should take the first supported cipher in the list sent by the client. See
the ciphers(1) command for more information.

-time length
specifies how long (in seconds) s_time should establish connections and optionally transfer payload
data from a server. Server and client performance and the link speed determine how many connections
s_time can establish.

NOTES

s_client can be used to measure the performance of an SSL connection. To connect to an SSL HTTP server
and get the default page the command

openssl s_time -connect servername:443 -www / -CApath yourdir -CAfile yourfile.pem -cipher commoncipher [-ssl3]

would typically be used (https uses port 443). 'commoncipher' is a cipher to which both client and server
can agree, see the ciphers(1) command for details.

If the handshake fails then there are several possible causes, if it is nothing obvious like no client
certificate then the -bugs, -ssl2, -ssl3 options can be tried in case it is a buggy server. In particular
you should play with these options before submitting a bug report to an OpenSSL mailing list.

A frequent problem when attempting to get client certificates working is that a web client complains it
has no certificates or gives an empty list to choose from. This is normally because the server is not
sending the clients certificate authority in its "acceptable CA list" when it requests a certificate. By
using s_client(1) the CA list can be viewed and checked. However some servers only request client
authentication after a specific URL is requested. To obtain the list in this case it is necessary to use
the -prexit option of s_client(1) and send an HTTP request for an appropriate page.

If a certificate is specified on the command line using the -cert option it will not be used unless the
server specifically requests a client certificate. Therefor merely including a client certificate on the
command line is no guarantee that the certificate works.

BUGS