Configure TLS

To enable Transport Layer Security (TLS) between the server and client you need to setup both the server and the client with appropriate certificates and configuration. The following instructions walk you through the setup process.


Server TLS Setup

On the server create 2 directories for working with the certificates and copy the script to the buildcerts directory that was just created:

mydir> mkdir $HOME/buildcerts
mydir> mkdir $HOME/certs
mydir> cp /usr/share/yumapro/util/ $HOME/buildcerts

Change the directory to the buildcerts directory, run the key generation script and check the files were created:

mydir> cd buildcerts
buildcerts> ./

buildcerts> ls -l

-rw-rw-r-- 1 andy andy  956 Mar 16 15:05 ca.crt
-rw-rw-r-- 1 andy andy  883 Mar 16 15:05 ca.csr
-rw-rw-r-- 1 andy andy 1708 Mar 16 15:05 ca.key
-rw-rw-r-- 1 andy andy   17 Mar 16 15:05
-rw-rw-r-- 1 andy andy  969 Mar 16 15:05 client.crt
-rw-rw-r-- 1 andy andy  891 Mar 16 15:05 client.csr
-rw-rw-r-- 1 andy andy 1708 Mar 16 15:05 client.key
-rwxrwxr-x 1 andy andy 1513 Feb 23 16:29
-rw-rw-r-- 1 andy andy  969 Mar 16 15:05 server.crt
-rw-rw-r-- 1 andy andy  891 Mar 16 15:05 server.csr
-rw-rw-r-- 1 andy andy 1704 Mar 16 15:05 server.key

Generating Certificates with a SAN

A Subject Alternative Name (SAN) can be configured into a TLS X.509 certificate if the OpenSSL version supports X509v3. Customize the parameters within the script as needed. There are 2 example scripts for generating keys.

  • : x509 certificates that rely on legacy Common Name field

  • : x509 certificates that use SANs instead

The script will generate keys and certs for the “restconf” site. You can use the keys created by this script to setup TLS for your restconf site as described in Setup TLS Certificates for the RESTCONF Site

The script will generate x509 certificates that use SANs. You can use the keys created by this script to setup TLS for your gNMI application.

Copy the certificates to their proper places:

buildcerts> sudo cp ca.crt /usr/local/share/ca-certificates/
buildcerts> cp server.crt ../certs/
buildcerts> cp server.key ../certs/
buildcerts> sudo update-ca-certificates
buildcerts> ls /etc/ssl/certs -l | grep ca.crt
lrwxrwxrwx 1 root root     39 Mar 16 15:52 ca.pem -> /usr/local/share/ca-certificates/ca.crt

The script update-ca-certificates uses the ca-certificates package. If you do not have this package on your system, then use the following steps, instead of the section above This could be the case if you are building a minimal footprint system.

This will create the required certificate links:

buildcerts> mkdir temp
buildcerts> sudo ln -s /usr/local/share/ca-certificates/ca.crt temp/ca.pem
buildcerts> sudo c_rehash temp
 Doing temp
buildcerts> sudo mv temp/* /etc/ssl/certs
buildcerts> ls -l /etc/ssl/certs | grep ca.pem
 lrwxrwxrwx 1 root root      6 Mar 16 08:00 56c899cd.0 -> ca.pem
 lrwxrwxrwx 1 root root      6 Mar 16 08:00 b2457b50.0 -> ca.pem
 lrwxrwxrwx 1 root root     39 Mar 16 08:00 ca.pem -> /usr/local/share/ca-certificates/ca.crt

Generate the Client Fingerprint:

certs> cd $HOME/buildcerts
buildcerts> openssl x509 -noout -fingerprint -sha1 -inform pem -in client.crt

SHA1         Fingerprint=4B:A7:05:1E:12:F7:BC:FF:2D:9E:48:66:0A:8B:CC:D7:A5:65:E5:97

Check the Client Subject Alternate Name:

If the script is used then the SAN field should be set in the client.crt file. Use the following command to check it. For example, if the email address '' was configured:

buildcerts> openssl x509 -noout -ext subjectAltName -in client.crt
X509v3 Subject Alternative Name:
   email:[email protected]

Create the --cert-usermap Parameter


The yumaworks-cert-usermap.yang module can now be used to configure Certificate to User Identity Mappings defined in RFC 7589. Refer to NETCONF Over TLS for additional details on using this module.

The --cert-usermap parameter is supported by netconfd-pro to map a user-name to a client fingerprint.

The parameter has the form:


For example if user=andy creates the SHA1 Fingerprint then the cert-usermap parameter line should be:

cert-usermap andy@4B:A7:05:1E:12:F7:BC:FF:2D:9E:48:66:0A:8B:CC:D7:A5:65:E5:97


Even though the CLI parameter will accept as few as 6 pairs of digits, the full fingerprint value should be used.

Add the --cert-usermap Parameter to the Server Configuration File

The default server configuration file is /etc/yumapro/netconfd-pro.conf. It can be different on some platforms, It can also be changed with the --config CLI parameter.

netconfd-pro {

    with-netconf-tls true
    netconf-tls-certificate ~/certs/server.crt
    netconf-tls-key ~/certs/server.key

    # use the parameter you created in the previous step, not this string
    cert-usermap andy@4B:A7:05:1E:12:F7:BC:FF:2D:9E:48:66:0A:8B:CC:D7:A5:65:E5:97

Client TLS Setup

Generate Keys

On the client create 2 directories for working with the certificates:


mydir> mkdir $HOME/buildcerts

mydir>mkdir $HOME/certs

Copy Keys to Server

On the server copy the files you created to the client machine using sftp:


mydir> cd $HOME/buildcerts
sftp> cd buildcerts
sftp> put *
sftp> bye

Now copy the certificates on the client to their proper places:


mydir> cd $HOME/buildcerts
buildcerts> sudo cp ca.crt /usr/local/share/ca-certificates
buildcerts> cp client.crt $HOME/certs/
buildcerts> cp client.key $HOME/certs/

Go to the /etc/ssl/certs directory, run updates and check the results:


buildcerts> cd /etc/ssl/certs
certs> sudo update-ca-certificates

certs> ls -l | grep ca.crt

lrwxrwxrwx 1 root root     39 Mar 16 16:25 ca.pem -> /usr/local/share/ca-certificates/ca.crt

Add yangcli-pro CLI Parameters for TLS

The parameters needed to use TLS must be added to the yangcli-pro.conf file.

If you have an existing yangcli-pro.conf then add the two parameter lines to the existing file. If you do not have an existing yangcli-pro.conf file then one needs to be created. The default is /etc/yumapro/yangcli-pro.conf but this can be changed with the --config CLI parameter.

yangcli-pro {

    ssl-certificate ~/certs/client.crt
    ssl-key ~/certs/client.key

Test the TLS Connection

Use the yangcli-pro Connect procedure to test the TLS connection and run the server as you would normally.

If the client TLS keys are configured so no password is required, then the "no-password" parameter can be used in the "connect" command:

Example connect command (for user 'andy' connecting to

> connect user=andy server= no-password transport=tls