Dynamic Connections

Integrate Keeper Connection Manager with external data sources using Encrypted JSON Authentication

Overview

Keeper Connection Manager can be configured to integrate with any custom software or 3rd party application using encrypted JSON files that simultaneously authenticate a user and grant them access to remote connections.

Installation

The Dynamic Connections feature requires installation of the Encrypted JSON Authentication module for Keeper Connection Manager. To activate this feature, update the JSON_* parameters in the Docker Compose file in the keeper/guacamole image.

JSON_SECRET_KEY

JSON_TRUSTED_NETWORKS

Activating these parameters loads an authentication extension for Keeper Connection Manager which authenticates users using JSON that have been signed using HMAC/SHA-256 and encrypted with AES-128 CBC. As this JSON contains all information describing the user being authenticated (including any connections they have access to), this extension can provide a simple means of integrating Keeper Connection Manager with external applications.

The JSON_SECRET_KEY must be 128 bits, specified as a 32-digit hexadecimal value, such as:

4c0b569e4c96df157eee1b65dd0e4d41

This key can be essentially anything as long as it is unpredictable. An easy way of generating such a key is to echo a passphrase through the "md5sum" utility. This is the technique OpenSSL itself uses to generate 128-bit keys from passphrases. For example:

$ echo -n "ThisIsATest" | md5sum
4c0b569e4c96df157eee1b65dd0e4d41  -

If encrypted JSON will only ever be received from a known set of machines or private subnets, you may wish to further restrict acceptance of received JSON to only those trusted machines using the JSON_TRUSTED_NETWORKS property. This field is a comma-separated list of trusted IP addresses and/or CIDR subnets. For example:

127.0.0.0/8, 10.0.0.0/8

JSON format

The general format of the JSON (prior to being encrypted, signed, and sent to Keeper Connection Manager), is as follows:

{

    "username" : "arbitraryUsername",
    "expires" : TIMESTAMP,
    "connections" : {
        "Connection Name" : {
            "protocol" : "PROTOCOL",
            "parameters" : {
                "name1" : "value1",
                "name2" : "value2",
                ...
            }
        },

        ...

    }

}

...where TIMESTAMP is a standard UNIX epoch timestamp with millisecond resolution (the number of milliseconds since midnight of January 1, 1970 UTC) and PROTOCOL is the internal name of any of Guacamole's supported protocols, such as vnc, rdp, or ssh.

The JSON will cease to be accepted as valid after the server time passes the timestamp. If no timestamp is specified, the data will not expire. This can be desirable, but should only be done after careful consideration. In most cases, it is critical that a timestamp is specified, limiting the use of the encrypted JSON to some reasonable time interval and preventing replay attacks.

The top-level JSON object which must be submitted to Keeper Connection Manager has the following properties:

Property name	Type	Description
username	string	The unique username of the user authenticated by the JSON. If the user is anonymous, this should be the empty string ("").
expires	number	The absolute time after which the JSON should no longer be accepted, even if the signature is valid, as a standard UNIX epoch timestamp with millisecond resolution (the number of milliseconds since midnight of January 1, 1970 UTC).
connections	object	The set of connections which should be exposed to the user by their corresponding, unique names. If no connections will be exposed to the user, this can simply be an empty object ({}).

Each connection defined within each submitted JSON object has the following properties:

Property name	Type	Description
protocol	string	The internal name of a supported protocol, such as vnc, rdp, ssh, etc.
parameters	object	An object representing the connection parameter name/value pairs to apply to the connection, as documented in the Guacamole manual.

Generating encrypted JSON

To authenticate a user with the above JSON format, the JSON must be both signed and encrypted using the same 128-bit secret key specified with the JSON_SECRET_KEY value in the Docker compose file.

1. Generate JSON in the format described above

2. Sign the JSON using the secret key (the same 128-bit key stored with the JSON_SECRET_KEY property) with HMAC/SHA-256. Prepend the binary result of the signing process to the plaintext JSON that was signed.

3. Encrypt the result of (2) above using AES in CBC mode, with the initial vector (IV) set to all zero bytes.

4. Encode the encrypted result using base64.

5. POST the encrypted result to the /api/tokens REST endpoint as the value of an HTTP parameter named data (or include it in the URL of any Keeper Connection Manager page as a query parameter named data).

For example, if Keeper is running on kcm.example.com and BASE64_RESULT is the result of the above process, the equivalent run of the "curl" utility would be:

$ curl --data-urlencode "data=BASE64_RESULT" https://kcm.example.com/api/tokens

Be sure to URL-encode the base64-encoded result prior to POSTing it to /api/tokens or including it in the URL. Base64 can contain both "+" and "=" characters, which have special meaning within URLs.

If the data is invalid in any way, if the signature does not match, if decryption or signature verification fails, or if the submitted data has expired, the REST service will return an invalid credentials error and fail without user-visible explanation. Details describing the error that occurred will be in the KCM logs.