What is Tachyon Agent Historic Data Capture?

The Tachyon Agent, while running, continuously captures details of certain events as they happen, in a similar way to Windows Task Manager or Perfmon.  During startup, the Agent is able to detect some events that occurred when it was not running. Data is regularly written into a local, compressed and encrypted persistent store, called an inventory.  The inventory is accessible to the Agent language as SQL tables. The Agent periodically aggregates data in order to minimise the amount of storage required, so that each capture source has a live, hourly, daily and monthly table. The whole process is designed to minimise impact on device performance, storage and security.

Configuration options for each capture source are described in the public documentation reference for Tachyon Agent configuration properties. The defaults are the same for each capture source, but aggregation and retention settings can be set individually for each table.

The Agent has two key mechanisms of knowing when an event occurs that is of interest - event-based and polling-based

• Event-based relies on a source external to the Agent (normally the operating system) providing a notification to indicate that something has happened
• Polling-based is where the Agent will periodically check a source of data and work out what has changed by looking at differences in the data returned. Polling intervals means some brief events that occur between polls can be missed.

On Windows, the Agent is able to use Event Tracing for Windows (ETW). However, the Agent can be configured to use polling instead of ETW for individual capture sources. 

The table below lists currently supported capture sources, on which OS they are supported, and which capture method is used by default.  See Agent Historic Data Capture regarding Windows XP, Vista and Windows Server 2003.

How do I retrieve the data from the Tachyon Agent devices?

Live and aggregated historic data is available in inventory tables.

/* Sum the number of connections made per process today */
SELECT    SUM(ConnectionCount) AS Connections
,         ProcessName
FROM      $TCP_Daily
WHERE     TS = DATETRUNC(STRFTIME("%s", "now"), "day")
GROUP BY  ProcessName;

Note the below example uses LIKE because the inventory tables are not created with COLLATE NOCASE, and need to be queried in a case-sensitive fashion. If ProcessName = "chrome.exe" is used then it will not match "Chrome.exe" or "chrome.EXE".

SELECT * FROM $Process_Live WHERE ProcessName LIKE "chrome.exe"

How is the data managed?

The Tachyon Agent automatically aggregates and grooms data in each inventory table, according to aggregation intervals and data retention settings which are configurable in the Agent configuration file.  

• Default aggregation cycle interval is every 60 seconds, therefore it may take up to a minute before an event appears in an aggregated table
• Default retention for live tables is 5000 entries provided at least 3 aggregation cycles have occurred (older entries are deleted to make room for new entries)
• Default retention for hourly tables is a rolling 24 hours.
• Default retention for daily tables is a rolling 31 days.
• Default retention for monthly tables is a rolling 12 months.

Each aggregated table is built from the live table, and does not have a dependency on other aggregated tables. For example, Monthly is fed by Live, not fed by Daily. This allows retention settings to be configured independently for each table.

Data is stored in a local, compressed and encrypted persistent store, which persists during an Agent upgrade, uninstall and re-installation, unless specifically deleted.

If the Agent is unable to write to storage (out of disk space or other file-system problems), it will fail but continue monitoring in the hope this situation will improve later.

Historic data capture inventory schema

The following table shows the fields which exist only in the Live and Aggregated (Hourly, Daily, Monthly) tables.

Timestamps

The timestamp column (TS) in each table is stored in Unix Epoch format. Defined as the number of seconds that have elapsed since 00:00:00 Coordinated Universal Time (UTC), Thursday, 1 January 1970

To convert to a readable text format use the datetime SQL operation.

select Fqdn, datetime(TS, "unixepoch") as TS_ from $DNS_Hourly where Fqdn like "%facebook%";

Timestamps are truncated in the aggregated tables.

• Hourly - time is truncated to each hour - so an event that occurred at 2017-01-27 18:03:54 would be included in the summary for 2017-01-27 18:00:00
• Daily - time is truncated to midnight on each day - so an event that occurred at 2017-01-27 18:03:54 would be included in the summary for 2017-01-27 00:00:00
• Monthly - time is truncated to midnight on the first day of each month - so an event that occurred at 2017-01-27 18:03:54 would be included in the summary for 2017-01-01 00:00:00

DNS resolutions

When using polling, the local DNS cache is queried for all unique FQDNs. This includes an initial scan of cache entries created before the Agent starts, which are stored with the same timestamp. New entries that appear in the cache are deemed to correspond to new resolutions and stored with the timestamp of when the polling occurred.

When using ETW, the Agent attempts to capture DNS queries at the point that they are made. The query is captured, not the result of that query. That is, the Agent will capture a request to resolve an FQDN which may ultimately not be resolvable.  The DNS cache is not scanned.

Process executions

On Windows, the Agent runs as LOCAL SYSTEM, therefore details of almost every process will be available; however some processes may not be accessible because of permissions.

The Agent captures process starts; it does not track how long the process has been running, or how much CPU-time (or user/kernel/active time) the process has used.

Each time the Tachyon Agent starts it does an initial scan of processes before it starts capturing, and will use that time to record when these processes started.

Software installations

Each time the Tachyon Agent starts it does an initial scan of install software before it starts capturing. Since the Agent has no way of knowing when this install/uninstall happened, it will mark the event as having occurred "now".

On Windows, software installations are read from the registry key HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall and HKLM\SOFTWARE\Wow6432Node\Microsoft\Windows\CurrentVersion\Uninstall

Per-user installations are not yet supported.

Linux does not distinguish between O/S packages (even the kernel) and application packages; they are all software.

Outbound TCP connections

The Agent captures TCP connections, not UDP connections - as UDP is inherently connectionless (each packet sent is effectively a new connection).

Each time the Tachyon Agent starts it does an initial scan of connections before it starts capturing. A limitation of the Windows API is means that all established TCP connections, whether inbound or outbound, are captured; there is no way to distinguish between the two. This means that it is possible for the Agent to double-capture a connection if that connection was established before the Agent stops monitoring, and still exists when the Agent starts monitoring again, for example between Agent restarts. Unlike other capture sources, there is no persistent storage setting to prevent double-counting.

The Agent captures initial "connect" requests, not just successful connection establishment. This means that an attempt to perform a connection will be captured, even if that connection does not complete, for example, because of a timeout, or the server-side does not permit the connection.

Process stabilizations

On Windows, the Agent runs as LOCAL SYSTEM, therefore details of almost every process will be available; however some processes may not be accessible because of permissions. The Agent captures only information that can be accessed by LOCAL SYSTEM -  as such it does not check the UI responsiveness of a process.

By default, process stabilization monitoring is not active. To monitor processes, they must be specified in the Agent configuration file:

• Add Module.Inventory.ProcessStabilization.MonitoredProcesses=<string> to the Agent configuration file.
• This is a list of comma separated values, and the case is not significant. For example, winword.exe and WINWORD.EXE are treated the same.
• The list of monitored processes does not currently have a limit, however adding a large list of processes to monitor can cause performance degradation and the process stabilization time will become less accurate.

A process' resource usage is tracked, and it will be considered stable once it's resource utilisation has stopped fluctuating. The margin in which a process is considered stable can be modified in the Agent configuration file. This is not reccommended.

• This margin is controlled by the fuzziness Agent configuration setting.
• Add Module.Inventory.ProcessStabilization.Fuzziness=<integer> to the agent configuration file. It cannot be lower than 1, and cannot exceed 66. The default is 5.

A process that exits before it is considered stable will not be recorded. Currently, such processes will be discarded. A warning line is logged when this occurs.

Aggregation is grouped by the UserName and ExecutableName fields.