Difference between revisions of "FAQ english"

From Fail2ban
Jump to: navigation, search
(Removed spam)
Line 1: Line 1:
http://gnwnguh.blackapplehost.com/hockey-life-online.html read life online
http://oiociqe.blackapplehost.com/watch-one-tree-hill-season-3-online-free.html watch one tree hill online now
http://oiociqe.blackapplehost.com/fly-line-fishing.html fly fishing rod sage
http://gnwnguh.blackapplehost.com/adobe-cs3-keygen.html adobe acrobat 8 keygen
http://caewxhq.freewhost.com/fitness-center-san-antonio.html jazzercise fitness center
http://caewxhq.freewhost.com/glass-guide-used-car-prices.html glass slipper carriage service
http://oiociqe.blackapplehost.com/download-all-windows-xp.html download a windows xp
http://whlpoog.blackapplehost.com/high-school-racine-wisconsin.html oregon wisconsin schools
http://pciqgfi.yourfreehosting.net/diablo-2-lod-character-editor.html diablo 2 lod character editor
http://amwawoe.blackapplehost.com/perfect-posture-back-support.html posture back support bra
http://gnwnguh.blackapplehost.com/museum-of-science-technology.html museum of space and science
http://njulboh.yourfreehosting.net/fantasy-football-magazine.html fantasy football league management
http://whlpoog.blackapplehost.com/lever-rifle.html rifle purchase
http://whlpoog.blackapplehost.com/hair-color-conditioner.html deep hair conditioner
http://oiociqe.blackapplehost.com/maine-sport-fishing.html northern sport fishing products
http://oiociqe.blackapplehost.com/watch-big-brother-9-live.html watch big brother cbs
http://caewxhq.freewhost.com/vermont-deer-hunting-season.html white deer hunting
http://amwawoe.blackapplehost.com/one-tree-hill-episode-510.html one tree hill season finale episode
http://caewxhq.freewhost.com/catholic-calendar-for-2008.html catholic calendar for may 2008
http://njulboh.yourfreehosting.net/homemade-halloween-costume-ideas.html homemade tinkerbell costume
http://whlpoog.blackapplehost.com/plano-colored-contact-lenses.html theatrical colored contact lenses
http://whlpoog.blackapplehost.com/kids-candy-corn-halloween-costumes.html kids costumes australia
http://pciqgfi.yourfreehosting.net/art-of-tying-the-wet-fly-and-fishing-the.html a fly fishing rod
http://gnwnguh.blackapplehost.com/chesepeake-bay-fishing-report.html cocoa beach fishing report
http://pciqgfi.yourfreehosting.net/army-costumes-for-kids.html army costumes for kids
http://njulboh.yourfreehosting.net/minor-league-baseball-teams.html minor league baseball team
http://caewxhq.freewhost.com/disney-mulan-costume.html costume in disney
http://pciqgfi.yourfreehosting.net/richest-soccer-club.html river soccer club
http://njulboh.yourfreehosting.net/back-posture-supports.html back pain sitting posture
http://amwawoe.blackapplehost.com/soccer-football-federation.html soccer football video
http://pciqgfi.yourfreehosting.net/country-music-free-videos.html free country music videos
http://amwawoe.blackapplehost.com/how-to-cast-fly-fishing.html kaufmans fly fishing
http://gnwnguh.blackapplehost.com/hand-blown-glass-art.html blown glass chandelier
http://njulboh.yourfreehosting.net/channel-nine-news-video.html channel no 1 news
http://amwawoe.blackapplehost.com/magnavox-tv-remote-controls.html remote controlled light switch
== '''Configuration''' ==
== '''Configuration''' ==

Revision as of 18:21, 30 December 2008


What is the main configuration file for Fail2ban?

Fail2ban configuration process is rather simple. There is only one configuration file, where Fail2ban can be fully configured, this file is located at: /etc/fail2ban/fail2ban.conf

You are able to edit this file using any editor you want: vim, emacs, joe, ae...

Configuration file must be edited by root.

How can Fail2ban be configured?

This step is fully detailed at HOWTOs chapter

Can I exclude failed logins for selected users from resulting in a ban?

(I don't know, perhaps that's a feature request.)

Edit: Cause fail2ban didn't know anything of the username format logged in the specific file(s) (if usernames even get logged), it is only possible to exclude selected users in the regex of the service section.


What do I have to consider when using Fail2ban?

Especially on systems which provide SSH/CGI/PHP services to unknown users, it is possible to block other users from ssh and probably other services. How would a user do so? The user could issue:

logger -p auth.warning -t 'sshd[123]' 'Illegal user user1 from'

Or the malicious user may write via PHP's openlog()/syslog() to syslog.

Solution #1: This security hazard can be handled via ownership/permissions of /dev/log, which allows logging to all the users by default. Just add a group log, add all daemons and root to that group and be happy.

What about log injection?

Fail2ban parses log files of other services and thus it can be vulnerable to log injection. Daniel B. Cid describes this kind of issues in Attacking Log analysis tools. I strongly suggest that you read this article. We will always try to provide safe configuration files. However, you can use fail2ban-regex to test your configuration files against forged log lines.


I have Postfix on my system but no "mail" command. How can I get e-mail notifications?

As of version 0.8.1, "mail" actions are deprecated. Please use the "sendmail" ones instead. E.g. sendmail-whois instead of mail-whois in your jail.[conf|local].

You probably have the sendmail command. Copy /etc/fail2ban/action.d/mail-whois.conf to /etc/fail2ban/action.d/mail-whois.local, edit this file and replace mail with sendmail. Here is an example:

actionban = echo -en "From:root <fail2ban>
            To: <dest>
            Subject: [Fail2Ban] <name>: banned <ip>
            The IP <ip> has just been banned by Fail2Ban after
            <failures> attempts against <name>.\n\n
            Here are more information about <ip>:\n
            `whois <ip>`\n
            Fail2Ban"|sendmail -t  

mail.conf can be modified too.

Why do my CVS users using SSH getting blocked?

If you are using the Eclipse CVS integration with SSH, then each access of the CVS results in a failed access before a valid one is done. As a consequence your CVS users get banned from time to time.

I get the error "Please check the format and your locale settings"

The error looks like this:

ERROR: time data did not match format: data=Mar 21 10:00:50 fmt=%b %d %H:%M:%S
ERROR: Please check the format and your locale settings.

This is a known bug. Since 0.6.1, Fail2ban uses your locale settings for date and time format. However, some daemons do not take care of locale and write their log messages using the POSIX standard. Please look at this bug for more details.

You can try to override the LANG variable:

# LANG=en_US /etc/init.d/fail2ban restart

You can get all the available locale with:

# locale -a

How do I increase verbosity?

In order to increase the verbosity of Fail2ban, use the command line option -vvv for fail2ban-client and fail2ban (only for 0.6.x). Set loglevel to 4 in /etc/fail2ban/fail2ban.conf (only for > 0.6.x).

Fail2ban is running but not banning SSH bruteforce

NB:This example is based on a Debian system, but can be easily done on any distro.

The package is well installed:

# dpkg -l |grep fail                                               
ii  fail2ban                      0.8.1-2                         bans IPs that 
cause multiple authentication

The service is running:

# /etc/init.d/fail2ban status                                      
Status of authentication failure monitor: fail2ban is running

SSH jail is set up and ready:

# fail2ban-client status                                           
|- Number of jail:      1                                                       
`- Jail list:           ssh

SSH bruteforce logs are identified by fail2ban:

# fail2ban-regex /var/log/auth.log /etc/fail2ban/filter.d/sshd.conf
Success, the total number of match is 30

So, check that all your logs are synchronized: all logs files (auth.log, syslog,..) must use the same time reference (if your server is not very busy, there will probably be an important difference between the output of [1]date command and the last event logged in syslog. You can force to generate a log in syslog using the logger command and check then with the output of date command)

# date                                                             
Wed Nov 28 13:49:02 CET 2007                                                    
# tail -2 /var/log/auth.log                                        
Nov 28 13:39:12 <SERVERNAME> sudo: pam_unix(sudo:session): session opened for user roo
t by <user>(uid=0)                                                              
Nov 28 13:39:12 <SERVERNAME> sudo: pam_unix(sudo:session): session closed for user roo

If time reference is not the same everywhere, then fail2ban won't ban any IP!