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Server program that listens to incoming TLS connections.
The text printed is the same whether selected with the help option
(--help) or the more-help option (--more-help). more-help will print
the usage text by passing it through a pager program.
more-help is disabled on platforms without a working
fork(2) function. The PAGER environment variable is
used to select the program, defaulting to more. Both will exit
with a status code of 0.
gnutls-serv - GnuTLS server
Usage: gnutls-serv [ -<flag> [<val>] | --<name>[{=| }<val>] ]...
None:
-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
--alpn-fatal Send fatal alert on non-matching ALPN name
--noticket Don't accept session tickets
--earlydata Accept early data
--maxearlydata=num The maximum early data size to accept
- it must be in the range:
1 to 2147483648
--nocookie Don't require cookie on DTLS sessions
-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
--crlf Do not replace CRLF by LF in Echo server mode
-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
- prohibits the option 'require-client-cert'
-r, --require-client-cert Require a client certificate
--verify-client-cert If a client certificate is sent then verify it
--compress-cert=str Compress certificate
-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
--x509certfile=str X.509 Certificate file or PKCS #11 URL to use
--rawpkkeyfile=str Private key file (PKCS #8 or PKCS #12) or PKCS #11 URL to use
--rawpkfile=str Raw public-key file to use
- requires the option 'rawpkkeyfile'
--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=str The OCSP response to send to client
--ignore-ocsp-response-errors Ignore any errors when setting the OCSP response
-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
--keymatexport=str Label used for exporting keying material
--keymatexportsize=num Size of the exported keying material
--recordsize=num The maximum record size to advertise
- it must be in the range:
0 to 16384
--httpdata=file The data used as HTTP response
- file must pre-exist
--timeout=num The timeout period for server
--attime=str Perform validation at the timestamp instead of the system time
Version, usage and configuration options:
-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.
Please send bug reports to: <bugs@gnutls.org>
This is the “enable debugging” option. This option takes a ArgumentType.NUMBER argument. Specifies the debug level.
This is the “server’s hostname for server name extension” option. This option takes a ArgumentType.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.
This is the “specify alpn protocol to be enabled by the server” option. This option takes a ArgumentType.STRING argument. Specify the (textual) ALPN protocol for the server to use.
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.
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.
This is the “compress certificate” option. This option takes a ArgumentType.STRING argument. This option sets a supported compression method for certificate compression.
This is the “activate heartbeat support” option. Regularly ping client via heartbeat extension messages
This is the “priorities string” option. This option takes a ArgumentType.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
This is the “x.509 key file or pkcs #11 url to use” option. This option takes a ArgumentType.STRING argument. 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.
This is the “x.509 certificate file or pkcs #11 url to use” option. This option takes a ArgumentType.STRING argument. 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.
This is an alias for the x509keyfile option,
see the x509keyfile option documentation.
This is an alias for the x509certfile option,
see the x509certfile option documentation.
This is an alias for the x509keyfile option,
see the x509keyfile option documentation.
This is an alias for the x509certfile option,
see the x509certfile option documentation.
This is the “private key file (pkcs #8 or pkcs #12) or pkcs #11 url to use” option. This option takes a ArgumentType.STRING argument. Specify the private key file or URI to use; it must correspond to the raw public-key specified in –rawpkfile. Multiple key pairs can be specified with this option and in that case each occurrence of keyfile must be followed by the corresponding rawpkfile or vice-versa.
In order to instruct the application to negotiate raw public keys one must enable the respective certificate types via the priority strings (i.e. CTYPE-CLI-* and CTYPE-SRV-* flags).
Check the GnuTLS manual on section “Priority strings” for more information on how to set certificate types.
This is the “raw public-key file to use” option. This option takes a ArgumentType.STRING argument.
This option has some usage constraints. It:
Specify the raw public-key file to use; it must correspond to the private key specified in –rawpkkeyfile. Multiple key pairs can be specified with this option and in that case each occurrence of keyfile must be followed by the corresponding rawpkfile or vice-versa.
In order to instruct the application to negotiate raw public keys one must enable the respective certificate types via the priority strings (i.e. CTYPE-CLI-* and CTYPE-SRV-* flags).
Check the GnuTLS manual on section “Priority strings” for more information on how to set certificate types.
This is the “the ocsp response to send to client” option. This option takes a ArgumentType.STRING argument. If the client requested an OCSP response, return data from this file to the client.
This is the “ignore any errors when setting the ocsp response” option. That option instructs gnutls to not attempt to match the provided OCSP responses with the certificates.
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.
This is the “specify the pkcs #11 provider library” option. This option takes a ArgumentType.FILE argument. This will override the default options in /etc/gnutls/pkcs11.conf
This is the “perform validation at the timestamp instead of the system time” option. This option takes a ArgumentType.STRING argument timestamp. timestamp is an instance in time encoded as Unix time or in a human readable timestring such as "29 Feb 2004", "2004-02-29". Full documentation available at <https://www.gnu.org/software/coreutils/manual/html_node/Date-input-formats.html> or locally via info ’(coreutils) date invocation’.
This is the “output version information and exit” option. This option takes a ArgumentType.KEYWORD argument. 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.
This is the “display extended usage information and exit” option. Display usage information and exit.
This is the “extended usage information passed thru pager” option. Pass the extended usage information through a pager.
One of the following exit values will be returned:
Successful program execution.
The operation failed or the command syntax was not valid.
gnutls-cli-debug(1), gnutls-cli(1)
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
Next: gnutls-cli-debug Invocation, Previous: gnutls-cli Invocation, Up: Other included programs [Contents][Index]