Running your own TLS server based on GnuTLS can be useful when
debugging clients and/or GnuTLS itself. This section describes
how to use gnutls-serv as a simple HTTPS server.
The most basic server can be started as:
gnutls-serv --http --priority "NORMAL:+ANON-ECDH:+ANON-DH"
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:
$ 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
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.
$ 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
For use in the client, you may want to generate a client
certificate as well.
$ 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
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.
$ 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
For icing, we'll create a proxy certificate for the client too.
$ 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
Then start the server again:
$ gnutls-serv --http --x509cafile x509-ca.pem --x509keyfile x509-server-key.pem --x509certfile x509-server.pem
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.
$ 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
The next step is to add support for SRP authentication. This
requires an SRP password file created with srptool. To start the
server with SRP support:
gnutls-serv --http --priority NORMAL:+SRP-RSA:+SRP --srppasswdconf srp-tpasswd.conf --srppasswd srp-passwd.txt
Let's also start a server with support for PSK. This would
require a password file created with psktool.
gnutls-serv --http --priority NORMAL:+ECDHE-PSK:+PSK --pskpasswd psk-passwd.txt
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.
gnutls-serv --http --priority NORMAL:+CTYPE-CLI-RAWPK:+CTYPE-SRV-RAWPK --rawpkfile srv.rawpk.pem --rawpkkeyfile srv.key.pem
Finally, we start the server with all the earlier parameters and
you get this command:
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
