6. Managing ASGARD on the command line

6.1. Performance Tuning

6.1.1. Overview

The ASGARD agent polls the ASGARD server frequently for new tasks to execute. The default polling interval is 20 seconds in environments with up to 500 endpoints. In larger environments the polling interval increases dynamically up to 10 minutes for a configuration with 25.000 endpoints connected to a single ASGARD.

Additionally, ASGARD is configured to serve a maximum of 100 concurrent asset connections and 25 concurrent asset streams. Asset connections are short polls from the agent such as answering the question “do you have a new task for me?”. Asset streams are intense polls such as downloading THOR to the agent or uploading scan results back to ASGARD.

Requests that exceed the limits will receive an answer from ASGARD to repeat the request after N seconds, where N is calculated based on the current (over)load.

This factory preset behavior insures your ASGARD stays stable and responsive even if your ASGARD’s system resources are limited. Furthermore, you most likely will not overload your network or firewalls with high numbers of requests or downloads.

In order to modify ASGARDs performance settings edit /etc/nextron/asgard2/asgard.conf and restart the ASGARD service.

The default values are:

Value Description
LoadConnMax=100 Max. concurrent „Busy Connections”
LoadStreamMax=25 Max. concurrent „Busy Streams”
PingRateMin=10 Polling Rate with 0 connected Assets (seconds)
PingRateMax=600 Polling Rate with 25000 connected Assets (seconds)
PingRateFast=5 Polling Rate for Assets in Fast Ping Mode (seconds)

These values should work fine for most scenarios – regardless of the size of the installation. However, you may want to decrease PingRateMax in order to achieve a better responsiveness of your ASGARD infrastructure.

6.1.2. Overloading ASGARD

While temporary stream overloads are quite normal, connection overloads should not happen. If they do, either adjust your PingRateMax, your LoadConnMax or both.

ASGARD will indicate an overload with the “Connection Overload line” and the “Stream Overload line” within the graphs in the overview section (see picture below). If an ASGARD is in an overload situation it will postpone connections and streams but will not lose or drop tasks or be harmed in any way. ASGARD will recover to normal load automatically.


Asset Connections and Asset Streams

Stream overloads can happen temporarily (e.g. if you schedule a grouped scan or grouped task with an unlimited rate). The picture below shows such a normal overload situation that was caused by starting a grouped scan with an unlimited rate. This is the expected behavior. ASGARD will manage the load automatically and postpone streams until the load has returned to normal.


Asset Streams in an overload situation

The “Busy Streams” line indicates the number of streams currently active. As you might have guessed, the picture above was taken on an ASGARD in default configuration where the number of concurrent streams is set to the default value of 25.

6.2. Managing Logs

ASGARD will store all logs under /var/lib/nextron/asgard2/log

All logs will be rotated monthly for up to 14 months and zipped after one month.

Please copy the oldest log packages to another directory or to a dedicated log server in case you require longer retention periods. Do not modify the built-in rotation settings as this might interfere with ASGARD updates!

6.3. Creating Custom Agent Installer

ASGARD supports creation of custom installers. Custom installers can be configured in a way that agents show up with a preset label or with a preset proxy configuration.

In order to create your custom ASGARD agent, save the current agents stored in /var/lib/nextron/asgard2/installer/ to a directory of your choosing and run sudo asgard2-repacker with one or more of the following flags:

-labels string

Add initial labels to clients comma separated list, e.g. [label1,label2,label3]

-proxies string

Proxies to be used by agents comma separated list, e.g. [proxy1.nextron:3128,proxy2.nextron:3128]

Example: In order to create an installer for servers that initially show up in ASGARD with the label SQL-Servers use:

# sudo asgard2-repacker -label SQL-Servers

Your newly generated agents will show up in /var/lib/nextron/asgard2/installer and will immediately be available for download from the login page. You can store multiple custom agents under /var/lib/nextron/asgard2/installer/. In this case all agents will be available for download from ASGARDs login page.

You can obfuscate the default asgard2-agent name with a custom one. The chosen name will generate new agents which can be deployed to the endpoints. These agents will create a service with the chosen name and will have no reference to ASGARD.

-name string

E.g. sudo asgard2-repacker -name javax

This command will create a new agent for all operating systems. This is specially designed for cases where an agent obfuscation is required.

An installed agent with the name “javax” would look like this:

systemctl status javax
Loaded: loaded (/etc/systemd/system/javax.service; enabled; vendor preset: enabled)
Active: active (running) since Thu 2020-xx-xx 16:47:22 CET; 5s ago
Main PID: 20048 (javax-service)
   Tasks: 7 (limit: 4915)
Memory: 4.7M
CGroup: /system.slice/javax.service
        20048 /usr/sbin/javax-serviceMar 26 16:47:22 asgard2-dev systemd[1]: Started javax.service.

6.4. Backup and Restore

6.4.1. Backup

The command asgard-backup can be used to generate a backup of all configurations, assets, tags, user accounts, tasks etc. except:

  • Log files (ASGARD, THOR)
  • Playbook results (collected evidence)
  • Quarantined samples (Bifrost)
$ asgard2-backup
Writing backup to '/var/lib/nextron/asgard2/backups/20200427-1553.tar'
tar: Removing leading '/' from member names
tar: Removing leading '/' from hard link targets
Removing old backups (keeping the 5 most recent files)...

6.4.2. Restore

You can use the asgard-restore command to restore a backup.

$ asgard2-restore``
Usage: /usr/sbin/asgard2-restore <BACKUPFILE>
$ asgard2-restore`` ``/var/lib/nextron/asgard2/backups/20200427-1553.tar
Stopping services... Removed /etc/systemd/system/multi-user.target.wants/asgard2.service.
1+0 records in
1+0 records out
24 bytes copied, 3.2337e-05 s, 742 kB/s
Starting services... Created symlink /etc/systemd/system/multi-user.target.wants/asgard2.service → lib/systemd/system/asgard2.service. done.