gnutls-serv — GnuTLS server
gnutls-serv [ −flag [value] ...] [ −−opt−name [[=|]value] ...]
−d
number,
−−debug=numberEnable debugging.. This option takes an integer number as its argument. The value of number is constrained to being:
in the range 0 through 9999
Specifies the debug level.
−−noticketDon't accept session tickets.
−g,
−−generateGenerate Diffie-Hellman and RSA-export parameters.
−q,
−−quietSuppress some messages.
−−nodbDo not use a resumption database.
−−httpAct as an HTTP server.
−−echoAct as an Echo server.
−u,
−−udpUse DTLS (datagram TLS) over UDP.
−−mtu=numberSet MTU for datagram TLS. This option takes an integer number as its argument. The value of number is constrained to being:
in the range 0 through 17000
−a,
−−disable−client−certDo not request a client certificate.
−r,
−−require−client−certRequire a client certificate.
−−x509fmtderUse DER format for certificates to read from.
−−priority=stringPriorities string.
TLS algorithms and protocols to enable. You can use predefined sets of ciphersuites such as PERFORMANCE, NORMAL, SECURE128, SECURE256. Check the GnuTLS manual on section “Priority strings” for more information on allowed keywords
−−dhparams=fileDH params file to use.
−−x509cafile=stringCertificate file or PKCS #11 URL to use.
−−x509crlfile=fileCRL file to use.
−−pgpkeyfile=filePGP Key file to use.
−−pgpkeyring=filePGP Key ring file to use.
−−pgpcertfile=filePGP Public Key (certificate) file to use.
−−x509keyfile=stringX.509 key file or PKCS #11 URL to use.
−−x509certfile=stringX.509 Certificate file or PKCS #11 URL to use.
−−x509dsakeyfile=stringAlternative X.509 key file or PKCS #11 URL to use.
−−x509dsacertfile=stringAlternative X.509 Certificate file or PKCS #11 URL to use.
−−x509ecckeyfile=stringAlternative X.509 key file or PKCS #11 URL to use.
−−x509ecccertfile=stringAlternative X.509 Certificate file or PKCS #11 URL to use.
−−pgpsubkey=stringPGP subkey to use (hex or auto).
−−srppasswd=fileSRP password file to use.
−−srppasswdconf=fileSRP password configuration file to use.
−−pskpasswd=filePSK password file to use.
−−pskhint=stringPSK identity hint to use.
−p
number,
−−port=numberThe port to connect to. This option takes an integer number as its argument.
−l,
−−listPrint a list of the supported algorithms and modes.
Print a list of the supported algorithms and modes. If a priority string is given then only the enabled ciphersuites are shown.
−h,
−−helpDisplay usage information and exit.
−!,
−−more−helpPass the extended usage information through a pager.
−v
[{v|c|n}],
−−version[={v|c|n}]Output version of program and exit. The default mode is `v', a simple version. The `c' mode will print copyright information and `n' will print the full copyright notice.
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
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 DSA, you can also create a DSA key and certificate for the server. These credentials will be used in the final example below.
$ certtool −−generate−privkey −−dsa > x509−server−key−dsa.pem $ certtool −−generate−certificate −−load−privkey x509−server−key−dsa.pem −−load−ca−certificate x509−ca.pem −−load−ca−privkey x509−ca−key.pem −−template server.tmpl −−outfile x509−server−dsa.pem
The next step is to create OpenPGP credentials for the server.
gpg −−gen−key
Make a note of the OpenPGP key identifier of the newly
generated key, here it was 5D1D14D8. You will need to export the key
for GnuTLS to be able to use it.
gpg −a −−export 5D1D14D8 > openpgp−server.txt gpg −−export 5D1D14D8 > openpgp−server.bin gpg −−export−secret−keys 5D1D14D8 > openpgp−server−key.bin gpg −a −−export−secret−keys 5D1D14D8 > openpgp−server−key.txt
Let's start the server with support for OpenPGP credentials:
gnutls−serv −−http −−pgpkeyfile openpgp−server−key.txt −−pgpcertfile openpgp−server.txt
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 −−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 −−pskpasswd psk−passwd.txt
Finally, we start the server with all the earlier parameters and you get this command:
gnutls−serv −−http −−x509cafile x509−ca.pem −−x509keyfile x509−server−key.pem −−x509certfile x509−server.pem −−x509dsakeyfile x509−server−key−dsa.pem −−x509dsacertfile x509−server−dsa.pem −−pgpkeyfile openpgp−server−key.txt −−pgpcertfile openpgp−server.txt −−srppasswdconf srp−tpasswd.conf −−srppasswd srp−passwd.txt −−pskpasswd psk−passwd.txt
One of the following exit values will be returned:
0
(EXIT_SUCCESS)Successful program execution.
1
(EXIT_FAILURE)The operation failed or the command syntax was not valid.