DNS App Id Plugin

The DNS App ID plugin identifies traffic passing through your 128T router by applying pattern matching to hostnames contained in DNS requests it processes. You can then configure 128T services for these hostnames, and associate application names to influence routing policy. You can read more about 128T and its application identification concept here.

This plugin relies on the DNS Cache plugin for hostname resolution.

note

The instructions for installing and managing this plugin can be found here.

Configuration

In addition to the configuration snippet from the dns-cache plugin, the below configuration shows an example of dns-app-id configuration:

configure
authority
router lab-router
application-identification
mode module
exit
dns-app-id
enabled true
include-all-builtin-apps false
builtin-apps gmail
builtin-apps windows-update
custom-apps cnn
name cnn
domain-name cnn.com
domain-name *.cnn.com
exit
exit
exit
exit
exit
ElementTypeDescription
enabledbooleanDefault: true. Governs whether the DNS AppID behavior is enabled or not.
include-all-builtin-appsbooleanDefault: false. Enabling this feature automatically includes all builtin apps including new one's the plugin adds due to upgrades.
builtin-appsstringMultiple instance object. This can reference any built-in application patterns contained within the version of the plugin you're running.
custom-appssubelementMultiple instance object. Allows administrators to define custom patterns for matching applications.
custom-apps > namestringThe name of the custom-app. This value will subsequently be configured within a service > application-name to give treatment to that application.
custom-apps > descriptionstringA human-readable description of the custom application.
custom-apps > domain-namestringA wildcard expression (POSIX.2 fnmatch) to match DNS requests that 128T processes.

Built-In Patterns

Version History
ReleaseModification
1.2.0, 2.2.0include-builtin-apps was introduced
1.3.0, 2.3.0, 3.1.0Add YouTube as builtin pattern

The plugin contains built in application patterns for Gmail, Google Drive, YouTube, and Windows Update. The patterns were generated from the following published documents:

ApplicationDocument
Gmaillink
Google Drivelink
Windows Updatelink 1 [link 2](https://docs.microsoft.com/en-us/windows/deployment/update/windows-update-troubleshooting#device-cannot-access-update-fWindows Updateiles)
YouTubelink

By enabling the include-all-builtin-apps configuration, the plugin will automatically include all the available apps. This allows for new apps to be automatically included as new builtin apps are added over time. Alternatively, you can choose specific builtin apps by name, as shown in the snippet above. The values you can configure are gmail, google-drive, youtube and windows-update.

Custom Patterns

Version History
ReleaseModification
1.2.0, 2.2.0Support for adding custom-apps at authority level was introduced
1.3.0, 2.3.0, 3.1.0deprecate patterns in favor of domain-name for custom-apps

The plugin also allows the user to create their own definitions of applications by configuring a set of patterns to be used for matching the application. Each pattern must be a valid regex that will be applied to a FQDN to identify the application. The authority > dns-app-id > custom-apps config can be used to define patterns that apply to all the routers with dns-app-id functionality enabled. Also shown in the configuration snippet is the custom-app cnn that includes a list of patterns to be applied at the router level. The identification is dynamic, so you just need to update the configuration on the conductor to include new apps or patterns for your routers. When custom-apps are configured at the authority and router level, the two lists are combined at runtime for that particular router. For example, if the user configured a custom-app called zoom on the authority and another app called cnn on the router, the router will contain both the applications.

Each custom-app should use the domain-name instead of the deprecated patterns for identifying custom applications. It is POSIX.2 compliant with fnmatch.

Example

This example shows our builtin gmail application's pattern matching configured as a custom-app. You should not use this example in production, but is intended to document how to build out complicated pattern matching for an application.

custom-apps gmail
name gmail
domain-name *.client-channel.google.com
domain-name accounts.google.com
domain-name apis.google.com
domain-name clients.*.google.com
domain-name contacts.google.com
domain-name hangouts.google.com
domain-name *.googleusercontent.com
domain-name mail.google.com
domain-name www.google.com
domain-name *.gstatic.com
domain-name ogs.google.com
domain-name play.google.com
exit

Deprecated Patterns

The latest version is backwards compatabile with the patterns regex functionality for custom-apps however it is much more natural to use domain-name. In future releases, the patterns functionality will be obsoleted and removed.

note

The . character bears special meaning within regular expressions, and matches any single character. Because hostnames contain literal . characters, in order to explicitly reference a dot separator, you must prefix it with two backslash characters. I.e., to have a pattern match the hostname www.128technology.com, you would type it into the PCLI as www.128technology.com. The PCLI will render the double backslash characters as a single backslash when you show the configuration.

important

If you configure invalid regex patterns, you will see the log message invalid pattern for {name}, will never match!. This means the pattern you configured is not a valid regex therefore the pattern matching will fail for the app until the configuration is fixed.

Automatic Service Generation

Version History
ReleaseModification
1.2.0, 2.2.0This capability was introduced
2.3.0, 3.0.0The generate-as-hierarchical-services capability was introduced

The authority > dns-app-id configuration allows the user to automatically generate services for both the builtin and custom applications.

config
authority
dns-app-id
generate-services true
base-service internet
exit
exit
exit
ElementTypeDescription
generate-servicesbooleanDefault: false. Governs whether to automatically generate services for applications.
generate-as-hierarchical-servicesbooleanDefault: false. Whether to auto generate services as hierarchical services.
base-serviceservice-referenceThe generated application service will inherit all the properties such as access-policy, service-policy, etc, from the base service.
custom-appssubelementMultiple instance object. Allows administrators to define custom patterns for matching applications.
custom-apps > namestringThe name of the custom-app. This value will subsequently be configured within a service > application-name to give treatment to that application.
custom-apps > descriptionstringA human-readable description of the custom application.
custom-apps > patternsregexA regular expression pattern for matching to DNS requests that the 128T processes.

Refer to the Appendix for an example of the config generation.

Manually associating with a Service

When auto-generation is not an option, the user can configure the appropriate application services explicitly. Because the DNS AppID uses the same mechanism as a standard 128T AppID module, you'll reference the application using the application-name field within a service configuration. In the application-name field, use the custom-apps > name field as your key as shown here:

admin@labsystem1.fiedler# show config running authority service cnn
config
authority
service CNN-service
name CNN-service
description "CNN and associated hostnames"
scope private
application-name cnn
access-policy trusted
source trusted
permission allow
exit
service-policy data-best-effort
share-service-routes false
exit
exit
exit

Troubleshooting

Verify the services of the 128T-dns-app-id plugin:

  • systemctl status 128T-dns-app-id

Watch the journal for logging:

  • journalctl -u 128T-dns-app-id -f

You can modify the systemd service unit manually to update the log-level of the application from INFO to DEBUG. The systemd service unit is located at /usr/lib/systemd/system/128T-dns-app-id.service.

You can use show device-interface dns-cache to see all available hostnames and IP addresses found by this plugin.

========================================
tnode:dns-cache
========================================
Type: host
Forwarding: true
Mode: host
MAC Address: 76:23:37:ed:5c:ae
Admin Status: up
Operational Status: up
Redundancy Status: non-redundant
Speed: 1000
Duplex: full
in-octets: 3618779
in-unicast-pkts: 57795
in-errors: 0
out-octets: 2641623
out-unicast-pkts: 57722
out-errors: 0
records:
gmail:
172.217.165.141/32

Similarly you can use show application names.

admin@dc.router# show application names
Sat 2020-03-28 03:28:43 UTC
================== =============== ================ ===================== =====================
Application Name Session Count Ip Tuple Count Date Discovered Last Updated
================== =============== ================ ===================== =====================
gmail 0 15 2020-06-20 03:28:40 2020-06-20 03:28:40
google-drive 0 9 2020-06-20 03:28:40 2020-06-20 03:28:40
windows-update 0 1 2020-06-20 03:28:40 2020-06-20 03:28:40

Appendix

Consider the following example configuration

config
authority
dns-app-id
generate-services true
base-service internet
exit
router router1
name router1
dns-app-id
include-all-builtin-apps true
exit
exit
service internet
name internet
application-name icmp-probe
access-policy _internal_
source _internal_
exit
access-policy dns-cache-plugin
source dns-cache-plugin
exit
exit
exit
exit

The above configuration will use the internet service as a basis for auto generating services for all built in applications such as google-drive, gmail, etc. Here's what the generated configuration will look like.

config
authority
service gmail_internet
name gmail_internet
applies-to router
type router
router-name router1
exit
application-name icmp-probe
application-name gmail
access-policy _internal_
source _internal_
exit
access-policy dns-cache-plugin
source dns-cache-plugin
exit
exit
service google-drive_internet
name google-drive_internet
applies-to router
type router
router-name router1
exit
application-name icmp-probe
application-name google-drive
access-policy _internal_
source _internal_
exit
access-policy dns-cache-plugin
source dns-cache-plugin
exit
exit
service windows-update_internet
name windows-update_internet
applies-to router
type router
router-name router1
exit
application-name icmp-probe
application-name windows-update
access-policy _internal_
source _internal_
exit
access-policy dns-cache-plugin
source dns-cache-plugin
exit
exit
exit
exit

Release Notes

Release 2.3.1, 3.1.1

Issues Fixed

  • PLUGIN-1099 Fixed an incorrect pattern for matching YouTube application

Release 1.3.0, 2.3.0, 3.1.0

New Features and Improvements

  • PLUGIN-1077 Deprecate patterns in favor of domain-name for custom-apps
  • PLUGIN-1078 Add YouTube to builtins
  • PLUGIN-890 Add support to auto generate services as hierarchical services

Release 3.0.0

Issues Fixed

  • PLUGIN-768 Support the DNS App ID plugin in 128T versions 5.1.0 and greater.
  • PLUGIN-611 Added support for plugin state. Plugin state information can be accessed on the PCLI using show plugins state [router <router>] [node <node>] [{detail | summmary}] 128T-dns-app-id

Release 2.2.1

Issues Fixed

  • PLUGIN-993 Automatic generation of services not working after upgrade

    Resolution Fix the config generation script to read the data from the file on disk instead of standard input.

Release 1.2.0, 2.2.0

New Features and Improvements

  • PLUGIN-877 Add support for automatic builtin app inclusion, authority wide custom-apps, and automatic service generation.

    • A new toggle for automatically including all builtin applications to keep up-to-date with new apps being added via plugin upgrades.
    • Created a new dns-app-id plugin at the authority level to provide means for adding custom-apps that apply to all routers in the config with dns-app-id enabled.
    • Provide an option to automatically generate services for the configured applications.

Release 1.1.0, 2.1.0

Issues Fixed

  • PLUGIN-809 DNS app-id plugin installation fails due to dependency conflict.

    Resolution The 128T-dns-app-id-router RPM has been updated to accept all versions of 128T-dns-cache-router RPM.

Release 1.0.2, 2.0.2

Issues Fixed

  • PLUGIN-402 Ensure 128T monitors new file changes and applications restarts with 128T.
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