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

If you want a server with support for raw public-keys we can also add these
credentials. Note however that there is no identity information linked to these
keys as is the case with regular x509 certificates. Authentication must be done
via different means. Also we need to explicitly enable raw public-key certificates
via the priority strings.

@example
gnutls-serv --http --priority NORMAL:+CTYPE-CLI-RAWPK:+CTYPE-SRV-RAWPK \
            --rawpkfile srv.rawpk.pem \
            --rawpkkeyfile srv.key.pem
@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:+CTYPE-CLI-RAWPK:+CTYPE-SRV-RAWPK \
            --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 \
            --rawpkfile srv.rawpk.pem \
            --rawpkkeyfile srv.key.pem
@end example