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¶
Because this program does not have all the options of the
s_client(1)
program to turn protocols on and off, you may not be able to measure the
performance of all protocols with all servers.
The
-verify option should really exit if the server verification fails.
SEE ALSO¶
s_client(1),
s_server(1),
ciphers(1)