@node gnutls-serv Invocation

@section Invoking gnutls-serv

@pindex gnutls-serv

@ignore

#  -*- buffer-read-only: t -*- vi: set ro:

#

# DO NOT EDIT THIS FILE   (invoke-gnutls-serv.texi)

#

# It has been AutoGen-ed

# From the definitions    ../src/serv-args.def

# and the template file   agtexi-cmd.tpl

@end ignore

Server program that listens to incoming TLS connections.

This section was generated by @strong{AutoGen},

using the @code{agtexi-cmd} template and the option descriptions for the @code{gnutls-serv} program.

This software is released under the GNU General Public License, version 3 or later.

@anchor{gnutls-serv usage}

@subheading gnutls-serv help/usage (@option{--help})

@cindex gnutls-serv help

This is the automatically generated usage text for gnutls-serv.

The text printed is the same whether selected with the @code{help} option

(@option{--help}) or the @code{more-help} option (@option{--more-help}).  @code{more-help} will print

the usage text by passing it through a pager program.

@code{more-help} is disabled on platforms without a working

@code{fork(2)} function.  The @code{PAGER} environment variable is

used to select the program, defaulting to @file{more}.  Both will exit

with a status code of 0.

@exampleindent 0

@example

gnutls-serv - GnuTLS server

Usage:  gnutls-serv [ -<flag> [<val>] | --<name>[@{=| @}<val>] ]...

   -d, --debug=num            Enable debugging

                                - it must be in the range:

                                  0 to 9999

       --sni-hostname=str     Server's hostname for server name extension

       --sni-hostname-fatal   Send fatal alert on sni-hostname mismatch

       --alpn=str             Specify ALPN protocol to be enabled by the server

                                - may appear multiple times

       --alpn-fatal           Send fatal alert on non-matching ALPN name

       --noticket             Don't accept session tickets

   -g, --generate             Generate Diffie-Hellman parameters

   -q, --quiet                Suppress some messages

       --nodb                 Do not use a resumption database

       --http                 Act as an HTTP server

       --echo                 Act as an Echo server

   -u, --udp                  Use DTLS (datagram TLS) over UDP

       --mtu=num              Set MTU for datagram TLS

                                - it must be in the range:

                                  0 to 17000

       --srtp-profiles=str    Offer SRTP profiles

   -a, --disable-client-cert  Do not request a client certificate

   -r, --require-client-cert  Require a client certificate

       --verify-client-cert   If a client certificate is sent then verify it.

   -b, --heartbeat            Activate heartbeat support

       --x509fmtder           Use DER format for certificates to read from

       --priority=str         Priorities string

       --dhparams=file        DH params file to use

                                - file must pre-exist

       --x509cafile=str       Certificate file or PKCS #11 URL to use

       --x509crlfile=file     CRL file to use

                                - file must pre-exist

       --x509keyfile=str      X.509 key file or PKCS #11 URL to use

                                - may appear multiple times

       --x509certfile=str     X.509 Certificate file or PKCS #11 URL to use

                                - may appear multiple times

       --srppasswd=file       SRP password file to use

                                - file must pre-exist

       --srppasswdconf=file   SRP password configuration file to use

                                - file must pre-exist

       --pskpasswd=file       PSK password file to use

                                - file must pre-exist

       --pskhint=str          PSK identity hint to use

       --ocsp-response=file   The OCSP response to send to client

                                - file must pre-exist

   -p, --port=num             The port to connect to

   -l, --list                 Print a list of the supported algorithms and modes

       --provider=file        Specify the PKCS #11 provider library

                                - file must pre-exist

   -v, --version[=arg]        output version information and exit

   -h, --help                 display extended usage information and exit

   -!, --more-help            extended usage information passed thru pager

Options are specified by doubled hyphens and their name or by a single

hyphen and the flag character.

Server program that listens to incoming TLS connections.

@end example

@exampleindent 4

@anchor{gnutls-serv debug}

@subheading debug option (-d)

This is the ``enable debugging'' option.

This option takes a number argument.

Specifies the debug level.

@anchor{gnutls-serv sni-hostname}

@subheading sni-hostname option

This is the ``server's hostname for server name extension'' option.

This option takes a string argument.

Server name of type host_name that the server will recognise as its own. If the server receives client hello with different name, it will send a warning-level unrecognized_name alert.

@anchor{gnutls-serv alpn}

@subheading alpn option

This is the ``specify alpn protocol to be enabled by the server'' option.

This option takes a string argument.

@noindent

This option has some usage constraints.  It:

@itemize @bullet

@item

may appear an unlimited number of times.

@end itemize

Specify the (textual) ALPN protocol for the server to use.

@anchor{gnutls-serv require-client-cert}

@subheading require-client-cert option (-r)

This is the ``require a client certificate'' option.

This option before 3.6.0 used to imply --verify-client-cert.

Since 3.6.0 it will no longer verify the certificate by default.

@anchor{gnutls-serv verify-client-cert}

@subheading verify-client-cert option

This is the ``if a client certificate is sent then verify it.'' option.

Do not require, but if a client certificate is sent then verify it and close the connection if invalid.

@anchor{gnutls-serv heartbeat}

@subheading heartbeat option (-b)

This is the ``activate heartbeat support'' option.

Regularly ping client via heartbeat extension messages

@anchor{gnutls-serv priority}

@subheading priority option

This is the ``priorities string'' option.

This option takes a string argument.

TLS algorithms and protocols to enable. You can

use predefined sets of ciphersuites such as PERFORMANCE,

NORMAL, SECURE128, SECURE256. The default is NORMAL.

Check  the  GnuTLS  manual  on  section  ``Priority strings'' for more

information on allowed keywords

@anchor{gnutls-serv x509keyfile}

@subheading x509keyfile option

This is the ``x.509 key file or pkcs #11 url to use'' option.

This option takes a string argument.

@noindent

This option has some usage constraints.  It:

@itemize @bullet

@item

may appear an unlimited number of times.

@end itemize

Specify the private key file or URI to use; it must correspond to

the certificate specified in --x509certfile. Multiple keys and certificates

can be specified with this option and in that case each occurrence of keyfile

must be followed by the corresponding x509certfile or vice-versa.

@anchor{gnutls-serv x509certfile}

@subheading x509certfile option

This is the ``x.509 certificate file or pkcs #11 url to use'' option.

This option takes a string argument.

@noindent

This option has some usage constraints.  It:

@itemize @bullet

@item

may appear an unlimited number of times.

@end itemize

Specify the certificate file or URI to use; it must correspond to

the key specified in --x509keyfile. Multiple keys and certificates

can be specified with this option and in that case each occurrence of keyfile

must be followed by the corresponding x509certfile or vice-versa.

@anchor{gnutls-serv x509dsakeyfile}

@subheading x509dsakeyfile option

This is an alias for the @code{x509keyfile} option,

@pxref{gnutls-serv x509keyfile, the x509keyfile option documentation}.

@anchor{gnutls-serv x509dsacertfile}

@subheading x509dsacertfile option

This is an alias for the @code{x509certfile} option,

@pxref{gnutls-serv x509certfile, the x509certfile option documentation}.

@anchor{gnutls-serv x509ecckeyfile}

@subheading x509ecckeyfile option

This is an alias for the @code{x509keyfile} option,

@pxref{gnutls-serv x509keyfile, the x509keyfile option documentation}.

@anchor{gnutls-serv x509ecccertfile}

@subheading x509ecccertfile option

This is an alias for the @code{x509certfile} option,

@pxref{gnutls-serv x509certfile, the x509certfile option documentation}.

@anchor{gnutls-serv ocsp-response}

@subheading ocsp-response option

This is the ``the ocsp response to send to client'' option.

This option takes a file argument.

If the client requested an OCSP response, return data from this file to the client.

@anchor{gnutls-serv list}

@subheading list option (-l)

This is the ``print a list of the supported algorithms and modes'' option.

Print a list of the supported algorithms and modes. If a priority string is given then only the enabled ciphersuites are shown.

@anchor{gnutls-serv provider}

@subheading provider option

This is the ``specify the pkcs #11 provider library'' option.

This option takes a file argument.

This will override the default options in /etc/gnutls/pkcs11.conf

@anchor{gnutls-serv exit status}

@subheading gnutls-serv exit status

One of the following exit values will be returned:

@table @samp

@item 0 (EXIT_SUCCESS)

Successful program execution.

@item 1 (EXIT_FAILURE)

The operation failed or the command syntax was not valid.

@end table

@anchor{gnutls-serv See Also}

@subheading gnutls-serv See Also

gnutls-cli-debug(1), gnutls-cli(1)

@anchor{gnutls-serv Examples}

@subheading gnutls-serv Examples

Running your own TLS server based on GnuTLS can be useful when

debugging clients and/or GnuTLS itself.  This section describes how to

use @code{gnutls-serv} as a simple HTTPS server.

The most basic server can be started as:

@example

gnutls-serv --http --priority "NORMAL:+ANON-ECDH:+ANON-DH"

@end example

It will only support anonymous ciphersuites, which many TLS clients

refuse to use.

The next step is to add support for X.509.  First we generate a CA:

@example

$ certtool --generate-privkey > x509-ca-key.pem

$ echo 'cn = GnuTLS test CA' > ca.tmpl

$ echo 'ca' >> ca.tmpl

$ echo 'cert_signing_key' >> ca.tmpl

$ certtool --generate-self-signed --load-privkey x509-ca-key.pem \

  --template ca.tmpl --outfile x509-ca.pem

@end example

Then generate a server certificate.  Remember to change the dns_name

value to the name of your server host, or skip that command to avoid

the field.

@example

$ certtool --generate-privkey > x509-server-key.pem

$ echo 'organization = GnuTLS test server' > server.tmpl

$ echo 'cn = test.gnutls.org' >> server.tmpl

$ echo 'tls_www_server' >> server.tmpl

$ echo 'encryption_key' >> server.tmpl

$ echo 'signing_key' >> server.tmpl

$ echo 'dns_name = test.gnutls.org' >> server.tmpl

$ certtool --generate-certificate --load-privkey x509-server-key.pem \

  --load-ca-certificate x509-ca.pem --load-ca-privkey x509-ca-key.pem \

  --template server.tmpl --outfile x509-server.pem

@end example

For use in the client, you may want to generate a client certificate

as well.

@example

$ certtool --generate-privkey > x509-client-key.pem

$ echo 'cn = GnuTLS test client' > client.tmpl

$ echo 'tls_www_client' >> client.tmpl

$ echo 'encryption_key' >> client.tmpl

$ echo 'signing_key' >> client.tmpl

$ certtool --generate-certificate --load-privkey x509-client-key.pem \

  --load-ca-certificate x509-ca.pem --load-ca-privkey x509-ca-key.pem \

  --template client.tmpl --outfile x509-client.pem

@end example

To be able to import the client key/certificate into some

applications, you will need to convert them into a PKCS#12 structure.

This also encrypts the security sensitive key with a password.

@example

$ certtool --to-p12 --load-ca-certificate x509-ca.pem \

  --load-privkey x509-client-key.pem --load-certificate x509-client.pem \

  --outder --outfile x509-client.p12

@end example

For icing, we'll create a proxy certificate for the client too.

@example

$ certtool --generate-privkey > x509-proxy-key.pem

$ echo 'cn = GnuTLS test client proxy' > proxy.tmpl

$ certtool --generate-proxy --load-privkey x509-proxy-key.pem \

  --load-ca-certificate x509-client.pem --load-ca-privkey x509-client-key.pem \

  --load-certificate x509-client.pem --template proxy.tmpl \

  --outfile x509-proxy.pem

@end example

Then start the server again:

@example

$ gnutls-serv --http \

            --x509cafile x509-ca.pem \

            --x509keyfile x509-server-key.pem \

            --x509certfile x509-server.pem

@end example

Try connecting to the server using your web browser.  Note that the

server listens to port 5556 by default.

While you are at it, to allow connections using ECDSA, you can also

create a ECDSA key and certificate for the server.  These credentials

will be used in the final example below.

@example

$ certtool --generate-privkey --ecdsa > x509-server-key-ecc.pem

$ certtool --generate-certificate --load-privkey x509-server-key-ecc.pem \

  --load-ca-certificate x509-ca.pem --load-ca-privkey x509-ca-key.pem \

  --template server.tmpl --outfile x509-server-ecc.pem

@end example

The next step is to add support for SRP authentication. This requires

an SRP password file created with @code{srptool}.

To start the server with SRP support:

@example

gnutls-serv --http --priority NORMAL:+SRP-RSA:+SRP \

            --srppasswdconf srp-tpasswd.conf \

            --srppasswd srp-passwd.txt

@end example

Let's also start a server with support for PSK. This would require

a password file created with @code{psktool}.

@example

gnutls-serv --http --priority NORMAL:+ECDHE-PSK:+PSK \

            --pskpasswd psk-passwd.txt

@end example

Finally, we start the server with all the earlier parameters and you

get this command:

@example

gnutls-serv --http --priority NORMAL:+PSK:+SRP \

            --x509cafile x509-ca.pem \

            --x509keyfile x509-server-key.pem \

            --x509certfile x509-server.pem \

            --x509keyfile x509-server-key-ecc.pem \

            --x509certfile x509-server-ecc.pem \

            --srppasswdconf srp-tpasswd.conf \

            --srppasswd srp-passwd.txt \

            --pskpasswd psk-passwd.txt

@end example