pacct: Collect process accounting logs on Linux

1: pacct() options

Starting with version 3.2, AxoSyslog can collect process accounting logs on Linux systems.Process accounting is the method of recording and summarizing commands executed on Linux, for example, the commands being run, the user who executed the command, CPU time used by the process, exit code, and so on. When process accounting (also called pacct) is enabled on a system, the kernel writes accounting records to the /var/log/account/pacct file (might vary between different Linux distributions).

To use the pacct() driver, the following conditions must be met:

The AxoSyslog application must be compiled with the --enable-pacct option. Execute the syslog-ng -V command to check if your binary supports process accounting.
The pacctformat plugin must be loaded. By default, AxoSyslog automatically loads the available modules.
The scl.conf file must be included in your AxoSyslog configuration:
```
    @include "scl.conf"
```
Process accounting must be running on the host. You can enable it with the accton command.

The pacct() driver parses the fields of the accounting logs and transforms them into name-value pairs. The fields are defined in the manual page of the accounting log file (man acct), AxoSyslog prepends every field with the .pacct. prefix. For example, the ac_uid field that contains the id of the user who started the process will be available under the $.pacct.ac_uid name. These can be used as macros in templates, in filters to select specific messages, and so on.

To use the pacct() driver, use the following syntax.

   @version: 4.9.0
    @include "scl.conf"
    source s_pacct { pacct(); };
    ...
    log { source(s_pacct); destination(...); };

The pacct() driver is actually a reusable configuration snippet configured to handle Linux accounting logs. For details on using or writing such configuration snippets, see Reusing configuration blocks. You can find the source of the pacct configuration snippet on GitHub.

1 - pacct() options

The pacct() driver has the following options:

file()


Type:	filename with path
Default:	/var/log/account/pacct

Description: The file where the process accounting logs are stored — AxoSyslog reads accounting messages from this file.

follow-freq()


Type:	number
Default:	1

Description: Indicates that the source should be checked periodically. This is useful for files which always indicate readability, even though no new lines were appended. If this value is higher than zero, AxoSyslog will not attempt to use poll() on the file, but checks whether the file changed every time the follow-freq() interval (in seconds) has elapsed. Floating-point numbers (for example, 1.5) can be used as well.

hook-commands()

Description: This option makes it possible to execute external programs when the relevant driver is initialized or torn down. The hook-commands() can be used with all source and destination drivers with the exception of the usertty() and internal() drivers.

Note The AxoSyslog application must be able to start and restart the external program, and have the necessary permissions to do so. For example, if your host is running AppArmor or SELinux, you might have to modify your AppArmor or SELinux configuration to enable AxoSyslog to execute external applications.

Using `hook-commands()` when AxoSyslog starts or stops

To execute an external program when AxoSyslog starts or stops, use the following options:

`startup()`

Type:	string
Default:	N/A

Description: Defines the external program that is executed as AxoSyslog starts.

`shutdown()`

Type:	string
Default:	N/A

Description: Defines the external program that is executed as AxoSyslog stops.

Using the hook-commands() when AxoSyslog reloads

To execute an external program when the AxoSyslog configuration is initiated or torn down, for example, on startup/shutdown or during a AxoSyslog reload, use the following options:

`setup()`

Type:	string
Default:	N/A

Description: Defines an external program that is executed when the AxoSyslog configuration is initiated, for example, on startup or during a AxoSyslog reload.

`teardown()`

Type:	string
Default:	N/A

Description: Defines an external program that is executed when the AxoSyslog configuration is stopped or torn down, for example, on shutdown or during a AxoSyslog reload.

Example: Using hook-commands() with a network source

In the following example, the hook-commands() is used with the network() driver and it opens an iptables port automatically as AxoSyslog is started/stopped.

The assumption in this example is that the LOGCHAIN chain is part of a larger ruleset that routes traffic to it. Whenever the AxoSyslog created rule is there, packets can flow, otherwise the port is closed.

source {
    network(transport(udp)
    hook-commands(
          startup("iptables -I LOGCHAIN 1 -p udp --dport 514 -j ACCEPT")
          shutdown("iptables -D LOGCHAIN 1")
        )
     );
};