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User Tags

LogZilla's Rewrite Rules Feature also allows the extraction and "tagging" of any arbitrary data extracted from events.

For more examples please be sure to check our GitHub Page which also contains any recently added rules submitted by the community but not implemented in the software yet.

Extracting Insight From Arbitrary Data

User Tags allow extraction and transformation of any arbitrary data from incoming events in order to obtain insight from various metrics such as:

  • Device types
  • Users
  • Locations
  • GeoIP
  • Authentication Failures
  • Audit Log Tracking
  • Malware Types/Sources/Destinations

These are only a few of the thousands of possibilities of what users are able to extract as tags from LogZilla's rule parser.

"User Tags" makes it possible to extract and track any information which may provide insight into day-to-day NetOps, SecOps, DevOps, etc. functions.

For example, given a list of incoming events such as:

%AUTHPRIV-3-SYSTEM_MSG: pam_aaa:Authentication failed for user bob from
Log-in failed for user 'agents' from 'ssh'

It is easy to extract and track the name of the users as well as the source address of that user:

  • Create a new rule such as 100-failed-login-tracking.yaml
  • Add the pattern match and user tag of your choice
  • Set the rule to mark this event as actionable in the system (note that statuses may also be set as non-actionable).
      comment: "Auth Fail User Tracking"
        field: "message"
        op: "=~"
        value: "for (?:user)? '?([^\\s']+)'? from '?([^\\s']+)'?"
        authfail_users: "$1"
        authfail_source: "$2"
        status: "actionable"
  • Add your new rule using logzilla rules add 100-failed-login-tracking.yaml
  • Add a new TopN widget to any dashboard (such as Top Hosts) and edit that widget to select the newly created user tag field:

User Tags Field Selector

UT Field Select

  • Your TopN chart will now display the top 5 Client Usernames.

Top Auth Fail Usernames chart

Failed User Auth

Match/Update Based on Previously Created Tags

It is also possible to set a custom tag, then use that tag in the same rule or even other rules files. If a tag-based match/update is used, that tag should be created first of course. If created in another rule file, be sure that the rule file containing the new tag comes first alphabetically. For example:

001-rule.yaml - create the tag based on a message match:

        - "Extract denied List Name, Protocol and Port Numbers from Cisco Access List logs"
        - "Sample Log: Oct 4 22:33:40.985 UTC: %SEC-6-IPACCESSLOGP: list PUBLIC_INGRESS denied tcp ->, 1 packet"
        field: "message"
        op: "=~"
        value: "list (\\S+) denied (\\S+) \\d+\\.\\d+\\.\\d+\\.\\d+\\((\\d+)\\).+?\\d+\\.\\d+\\.\\d+\\.\\d+\\((\\d+)\\)"
        cisco_acl_deny_acl_name: "$1"
        cisco_acl_deny_src_proto: "$2"
        cisco_acl_deny_src_port: "$3"
        cisco_acl_deny_dst_port: "$4"

002-rule.yaml - use the tag created in 001-rule.yaml to map port numbers to names:

  first_match_only: true
      comment: "Match on previously created Cisco ACL tags and convert the port numbers extracted stored in that same tag to a name for ports 22, 23, 80 and 443"
        field: "cisco_acl_deny_dst_port"
        value: "22"
        cisco_acl_deny_dst_port: "ssh"
        field: "cisco_acl_deny_dst_port"
        value: "23"
        cisco_acl_deny_dst_port: "telnet"
        field: "cisco_acl_deny_dst_port"
        value: "80"
        cisco_acl_deny_dst_port: "http"
        field: "cisco_acl_deny_dst_port"
        value: "443"
        cisco_acl_deny_dst_port: "https"

Example 2

In the example below, a previous rule file (or even a rule in the same file which appears before this rule) has created the su_sessions user tag. The example below assumes this has already been done.

The rule below tells the system to match on su_sessions and set the program to su, but only if the matched value does not equal an empty string (blank messages).

      comment: "Track su sessions"
        field: "su_sessions"
        op: "ne"
        value: ""
        program: "su"


A helper script located on our GitHub is available to be used to create rules automatically using a tab separated file as input. You can download the script here

Input fields

The .tsv (tab-separated-values) file must contain at least 6 columns

Columns 1-4

Columns 1-4 must be:

addtag  matchString matchField  matchOp
For example

1    host    eq
Column 1

Indicates whether or not (0 or 1) a user tag should also be created for this entry

Column 2

The string you want to match on, for example: or foo bar baz

Column 3

The field to match on in LogZilla, such as host, program, message, etc.

Column 4

Defines the match Operator to use. Options are:

Operator Match Type Description
eq String or Integer Matches entire incoming message against the string/integer specified in the match condition
ne String or Integer Does not match anything in the incoming message match field.
gt Integer Only Given integer is greater than the incoming integer value
lt Integer Only Given integer is less than the incoming integer value
ge Integer Only Given integer is greater than or equal to the incoming integer value
le Integer Only Given integer is less than or equal to the incoming integer value
=~ RegEx Match based on RegEx pattern
!~ RegEx Does not match based on RegEx pattern
=* RegEx RegEx appears anywhere in the incoming message

Columns 5 and greater

All columns after column 4 are key-value pairs to be added. For example, given the following entire row in a file:

1    host    eq  deviceID    rtp-core-sw DeviceDescription   RTP Core Layer2 DeviceImportance    High    DeviceLocation  Raleigh DeviceContact   [email protected]
Columns 5-14 will be separated into key="value" pairs, like so:

Key = DeviceImportance, value = High
Key = DeviceDescription, value = RTP Core Layer2
Key = DeviceLocation, value = Raleigh
Key = deviceID, value = rtp-core-sw
Key = DeviceContact, value = [email protected]
Please make sure you have a value for every key. i.e., don't have something like:

1    host    eq  deviceID    rtp-core-sw DeviceDescription   RTP Core Layer2 DeviceImportance    High    DeviceLocation  Raleigh DeviceContact
(missing [email protected] at the end)

This would produce errors when the perl script runs, e.g.:

Odd number of elements in hash assignment at ./makemeta line 60, <$fh> line 4.
Use of uninitialized value $kvs{"DeviceContact"} in string comparison (cmp) at ./makemeta line 78, <$fh> line 4.
Use of uninitialized value $kvs{"DeviceContact"} in string comparison (cmp) at ./makemeta line 78, <$fh> line 4.
Use of uninitialized value $kvs{"DeviceContact"} in string comparison (cmp) at ./makemeta line 78, <$fh> line 4.
Use of uninitialized value $kvs{"DeviceContact"} in string eq at ./makemeta line 80, <$fh> line 4.


    -debug [-d] <1 or 2>
    -format [-f] (json or yaml - default: yaml)
    -infile [-i] (Input filename, e.g.: test.tsv)
    Sample test.tsv file:
    1 <TAB> host-a <TAB> host <TAB> eq <TAB> deviceID <TAB> lax-srv-01 <TAB> DeviceDescription <TAB> LA Server 1

User Tags

If column 1 on your .tsv contains a 1, user tags will also be created for every key/value pair. As such, you will now see these fields available in your widgets. For example, the following rule:

 - match:
      - field: host
        op: eq
        value: host-a
      metadata_importance: High
      metadata_roles: Core
      metadata_locations: Los Angeles
      message: $MESSAGE DeviceDescription="LA Server 1" DeviceLocation="Los Angeles" DeviceImportance="Low" deviceID="lax-srv-01" DeviceContact="[email protected]"
  - match:
      - field: message
        op: =~
        value: down
      message: $MESSAGE DeviceImportance="Med" DeviceDescription="NYC Router" DeviceLocation="New York" deviceID="nyc-rtr-01" DeviceContact="[email protected]"

Will produce fields available similar to the screenshot below:

Screenshot: Available Fields



  • Tag names are free-form allowing any alphabetic characters. Once a message matches the pattern, the tag is automatically created in the API, then made available in the UI. If a tag is created but does not show up in the UI, it may simply mean there have been no matches on it yet. (note: users may want to try a browser refresh to ensure a non-cached page is loaded).

  • Any _'s in the tag name will be converted to a space character when displayed in the UI.

  • Tagging highly variable data may result in degradation or even failure of metrics tracking (not log storage/search) based on the capability of your system. This is due to cardinality limitations in InfluxDB. The following article outlines this limitation in more detail.

NOTE: certain user tag names are reserved for LogZilla internal use, and cannot be used as user tags; in these cases you will need to choose an alternative (a simple option would be to prefix the field name with ut_). The reserved names are: * first_occurrence * last_occurrence * counter * message * host * program * cisco_mnemonic * severity * facility * status * type

CAUTION: Care should be taken to keep the number of tags below 1m entries per tag.

Tag Performance

As with any large amount of data stream manipulation, performance degradation can happen depending on many variables such as CPU, Memory, Disc I/O, and, of course, the way the rules are presented to the parsing engine.

Ensuring Good Rule Performance

When writing large rulesets, it may be useful to use a precheck match to match on a string before matching on a large regular expression pattern. The precheck in this context is not a special type, rather, it is the same syntax as a match type, but uses eq (string) instead of =~ (regex). This also ensures that "generic" regex patterns don't match on a message it was not intended for.

The example below shows how to use an eq match (string match) for the incoming event. Then, if the string matches, a more complex regex (=~) match may be used.

Sample "pre-match"
- comment:
  - 'Vendor: HP Aruba'
  - 'Type: Hardware'
  - 'Category: 802.1x'
  - 'Description: This log event informs the number of auth timeouts for the last
    known time for 802.1x authentication method.'
  - 'Sample Log: <NUMBER_OF> auth-timeouts for the last <TIME> sec.'
  - field: message
    op: eq
    value: auth-timeouts for the last
  - field: message
    op: =~
    value: \S+ auth-timeouts \S+ \S+ \S+ \S+ sec .*
    program: HP_Switch
    category: 802.1x
    type: hardware
    vendor: HP

Bad Regex

It's important to make sure that the regex used is the most efficient. This will go a long way when using thousands of rules. In the example above, a prematch should not even be used (but was for demonstrative purposes only). A much better method for the example above would have been to not use a prematch and simply use a better regex pattern such as \\S+ auth-timeouts for the last \\S+ sec.

Be sure to use a tool such as RegEx101 to make sure the patterns work and that they perform well.


A command-line tool logzilla rules may be used to perform various functions including:

  • list - List rewrite rules
  • reload - Reload rewrite rules
  • add - Add rewrite rule
  • remove - Remove rewrite rule
  • export - Save rule to file
  • enable - Enable rewrite rule
  • disable - Disable rewrite rule
  • errors - Show rules having errors, with counts
  • performance - Test rules single thread performance
  • test - Check rule for validity and correct operation

To add your rule, simply type logzilla rules add myfile.yaml

Tag Naming

For rules provided by LogZilla (and as a recommendation), user tag names will fall into one of two categories. The first category is the most common data fields found in event log messages. For these fields the user tags and meanings are:

User Tag Example Meaning
SrcIP source IPv4 address
SrcIPv6 2001:0db8:85a3:0000:0000:8a2e:0370:7334 source IPv6 address
DstIP destination IPv4 address
DstIPv6 2001:0db8:85a3:0000:0000:8a2e:0370:7334 destination IPv6 address
SrcPort dynamic source port (instead of numeric this will be provided as a descriptive abbreviation, or dynamic if usage unspecified)
DstPort https destination port (instead of numeric this will be provided as a descriptive abbreviation, or dynamic if usage unspecified)
Proto TCP communications protocol (typically TCP, UDP, or ICMP)
MAC 00:00:5e:00:53:af MAC address
IfIn enp8s0 interface in
IfOut enp8s0 interface out

The second category of user tag names is for all other tags besides the above list. This will obviously constitute a large variety of tag names. These tag names are set to be the same as the vendor field names, so that those familiar with the vendor event log messages will be able to find that same data as LogZilla user tags with the same names. Some random examples of such tags might be:

Vendor Field and User Tag Meaning
act action taken
cat category
cnt count
dhost destination host
dvchost device host