---
name: "fail2ban-regex"
section: "1"
platform: "linux"
package: "fail2ban"
version: "1.1.1-1"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/fail2ban-regex"
---

# fail2ban-regex(1)

test Fail2ban "failregex" option

## NAME

fail2ban-regex - test Fail2ban "failregex" option

## SYNOPSIS

**fail2ban-regex** \[*OPTIONS*\] *\<LOG\> \<REGEX\>* \[*IGNOREREGEX*\]

## DESCRIPTION

Fail2Ban  reads log file that contains password failure report and bans the corresponding IP addresses using firewall rules.

This tools can test regular expressions for "fail2ban".

### LOG:

- string

  a string representing a log line

- filename

  path to a log file (*/var/log/auth.log*)

- systemd-journal

  search systemd journal (systemd-python required), optionally with backend parameters, see \`man jail.conf\` for usage and examples (systemd-journal\[journalflags=1\]).

### REGEX:

- string

  a string representing a 'failregex'

- filter

  name of jail or filter, optionally with options (sshd\[mode=aggressive\])

- filename

  path to a filter file (filter.d/sshd.conf)

### IGNOREREGEX:

- string

  a string representing an 'ignoreregex'

## OPTIONS

- **--version**

  show program's version number and exit

- **-h**, **--help**

  show this help message and exit

- **-c** CONFIG, **--config**=*CONFIG*

  set alternate config directory

- **-d** DATEPATTERN, **--datepattern**=*DATEPATTERN*

  set custom pattern used to match date/times

- **--timezone**=*TIMEZONE*, **--TZ**=*TIMEZONE*

  set time-zone used by convert time format

- **-e** ENCODING, **--encoding**=*ENCODING*

  File encoding. Default: system locale

- **-r**, **--raw**

  Raw hosts, don't resolve dns

- **--usedns**=*USEDNS*

  DNS specified replacement of tags \<HOST\> in regexp ('yes' - matches all form of hosts, 'no' - IP addresses only)

- **-L** MAXLINES, **--maxlines**=*MAXLINES*

  maxlines for multi-line regex.

- **-m** JOURNALMATCH, **--journalmatch**=*JOURNALMATCH*

  journalctl style matches overriding filter file. "systemd-journal" only

- **-l** LOG\_LEVEL, **--log-level**=*LOG\_LEVEL*

  Log level for the Fail2Ban logger to use

- **-V**

  get version in machine-readable short format

- **-v**, **--verbose**

  Increase verbosity

- **--verbosity**=*VERBOSE*

  Set numerical level of verbosity (0..4)

- **--verbose-date**, **--VD**

  Verbose date patterns/regex in output

- **-D**, **--debuggex**

  Produce debuggex.com urls for debugging there

- **--no-check-all**

  Disable check for all regex's

- **-o** OUT, **--out**=*OUT*

  Set token to print failure information only (row, id, ip, msg, host, ip4, ip6, dns, matches, ...)

- **-i**, **--invert**

  Invert the sense of matching, to output non-matching lines.

- **--print-no-missed**

  Do not print any missed lines

- **--print-no-ignored**

  Do not print any ignored lines

- **--print-all-matched**

  Print all matched lines

- **--print-all-missed**

  Print all missed lines, no matter how many

- **--print-all-ignored**

  Print all ignored lines, no matter how many

- **-t**, **--log-traceback**

  Enrich log-messages with compressed tracebacks

- **--full-traceback**

  Either to make the tracebacks full, not compressed (as by default)

## AUTHOR

Written by Cyril Jaquier \<cyril.jaquier@fail2ban.org\>. Many contributions by Yaroslav O. Halchenko, Steven Hiscocks, Sergey G. Brester (sebres).

## REPORTING BUGS

Report bugs to https://github.com/fail2ban/fail2ban/issues

## COPYRIGHT

Copyright © 2004-2008 Cyril Jaquier, 2008- Fail2Ban Contributors\
 Copyright of modifications held by their respective authors. Licensed under the GNU General Public License v2 (GPL).

## SEE ALSO

[fail2ban-client(1)](/fail2ban-client/1.md) [fail2ban-server(1)](/fail2ban-server/1.md) [jail.conf(5)](/jail.conf/5.md)