mirror of https://github.com/fail2ban/fail2ban
You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
484 lines
15 KiB
484 lines
15 KiB
__ _ _ ___ _
|
|
/ _|__ _(_) |_ ) |__ __ _ _ _
|
|
| _/ _` | | |/ /| '_ \/ _` | ' \
|
|
|_| \__,_|_|_/___|_.__/\__,_|_||_|
|
|
|
|
================================================================================
|
|
How to develop for Fail2Ban
|
|
================================================================================
|
|
|
|
Fail2Ban uses GIT (http://git-scm.com/) distributed source control. This gives
|
|
each developer their own complete copy of the entire repository. Developers can
|
|
add and switch branches and commit changes when ever they want and then ask a
|
|
maintainer to merge their changes.
|
|
|
|
Fail2Ban uses GitHub (https://github.com/fail2ban/fail2ban) to manage access to
|
|
the Git repository. GitHub provides free hosting for open-source projects as
|
|
well as a web-based Git repository browser and an issue tracker.
|
|
|
|
If you are familiar with Python and you have a bug fix or a feature that you
|
|
would like to add to Fail2Ban, the best way to do so it to use the GitHub Pull
|
|
Request feature. You can find more details on the Fail2Ban wiki
|
|
(http://www.fail2ban.org/wiki/index.php/Get_Involved)
|
|
|
|
Pull Requests
|
|
=============
|
|
|
|
When submitting pull requests on GitHub we ask you to:
|
|
* Clearly describe the problem you're solving;
|
|
* Don't introduce regressions that will make it hard for systems adminstrators
|
|
to update;
|
|
* If adding a major feature rebase your changes on master and get to a single commit;
|
|
* Include test cases (see below);
|
|
* Include sample logs (if relevant);
|
|
* Include a change to the relevant section of the ChangeLog; and
|
|
* Include yourself in THANKS if not already there.
|
|
|
|
Filters
|
|
=======
|
|
|
|
* Include sample logs with 1.2.3.4 used for IP addresses and
|
|
example.com/example.org used for DNS names
|
|
* Ensure sample log is provided in testcases/files/logs/ with same name as the
|
|
filter. Each log line should include match meta data for time & IP above
|
|
every line (see other sample log files for examples)
|
|
* Ensure regexs start with a ^ and are restrictive as possible. E.g. not .* if
|
|
\d+ is sufficient
|
|
* Use the functionality of regexs http://docs.python.org/2/library/re.html
|
|
* Take a look at the source code of the application. You may see optional or
|
|
extra log messages, or parts there of, that need to form part of your regex.
|
|
|
|
If you only have a basic knowledge of regular repressions read
|
|
http://docs.python.org/2/library/re.html first.
|
|
|
|
Filter Security
|
|
---------------
|
|
|
|
Poor filter regular expressions are suseptable to DoS attacks.
|
|
|
|
When a remote user has the ability to introduce text that will match the
|
|
filter regex, such that the inserted text matches the <HOST> part, they have the
|
|
ability to deny any host they choose.
|
|
|
|
So the <HOST> part must be anchored on text generated by the application, and not
|
|
the user, to a sufficient extent that the user cannot insert the entire text.
|
|
|
|
Filters are matched against the log line with their date removed.
|
|
|
|
Ideally filter regex should anchor to the beginning and end of the log line
|
|
however as more applications log at the beginning than the end, achoring the
|
|
beginning is more important. If the log file used by the application is shared
|
|
with other applications, like system logs, ensure the other application that
|
|
use that log file do not log user generated text at the beginning of the line,
|
|
or, if they do, ensure the regexs of the filter are sufficient to mitigate the
|
|
risk of insertion.
|
|
|
|
When creating a regex that extends back to the begining remember the date part
|
|
has been removed within fail2ban so theres no need to match that. If the format
|
|
is like '<date...> error 1.2.3.4 is evil' then you will need to match the < at
|
|
the start so here the regex would start like '^<> <HOST> is evil$'.
|
|
|
|
Some applications log spaces at the end. If you're not sure add \s*$ as the
|
|
end part of the regex.
|
|
|
|
Examples of poor filters
|
|
------------------------
|
|
|
|
1. Too restrictive
|
|
|
|
We find a log message:
|
|
|
|
Apr-07-13 07:08:36 Invalid command fial2ban from 1.2.3.4
|
|
|
|
We make a failregex
|
|
|
|
^Invalid command \S+ from <HOST>
|
|
|
|
Now think evil. The user does the command 'blah from 1.2.3.44'
|
|
|
|
The program diliently logs:
|
|
|
|
Apr-07-13 07:08:36 Invalid command blah from 1.2.3.44 from 1.2.3.4
|
|
|
|
And fail2ban matches 1.2.3.44 as the IP that it ban. A DoS attack was successful.
|
|
|
|
The fix here is that the command can be anything so .* is approprate.
|
|
|
|
^Invalid command .* from <HOST>
|
|
|
|
Here the .* will match until the end of the string. Then realise it has more to
|
|
match, i.e. "from <HOST>" and go back until it find this. Then it will ban
|
|
1.2.3.4 correctly. Since the <HOST> is always at the end, end the regex with a $.
|
|
|
|
^Invalid command .* from <HOST>$
|
|
|
|
Note if we'd just had the expression:
|
|
|
|
^Invalid command \S+ from <HOST>$
|
|
|
|
Then provided the user put a space in their command they would have never been
|
|
banned.
|
|
|
|
2. Filter regex can match other user injected data
|
|
|
|
From the apache vulnerability CVE-2013-2178
|
|
( original ref: https://vndh.net/note:fail2ban-089-denial-service ).
|
|
|
|
An example bad regex for apache:
|
|
|
|
failregex = [[]client <HOST>[]] user .* not found
|
|
|
|
Since the user can do a get request on:
|
|
|
|
GET /[client%20192.168.0.1]%20user%20root%20not%20found HTTP/1.0
|
|
Host: remote.site
|
|
|
|
Now the log line will be:
|
|
|
|
[Sat Jun 01 02:17:42 2013] [error] [client 192.168.33.1] File does not exist: /srv/http/site/[client 192.168.0.1] user root not found
|
|
|
|
As this log line doesn't match other expressions hence it matches the above
|
|
regex and blocks 192.168.33.1 as a denial of service from the HTTP requester.
|
|
|
|
3. Applicaiton generates two identical log messages with different meanings
|
|
|
|
If the application generates the following two messages under different
|
|
circmstances:
|
|
|
|
client <IP>: authentication failed
|
|
client <USER>: authentication failed
|
|
|
|
|
|
Then it's obvious that a regex of "^client <HOST>: authentication
|
|
failed$" will still cause problems if the user can trigger the second
|
|
log message with a <USER> of 123.1.1.1.
|
|
|
|
Here there's nothing to do except request/change the application so it logs
|
|
messages differently.
|
|
|
|
|
|
Code Testing
|
|
============
|
|
|
|
Existing tests can be run by executing `fail2ban-testcases`. This has options
|
|
like --log-level that will probably be useful. `fail2ban-testcases --help` for
|
|
full options.
|
|
|
|
Test cases should cover all usual cases, all exception cases and all inside
|
|
/ outside boundary conditions.
|
|
|
|
Test cases should cover all branches. The coverage tool will help identify
|
|
missing branches. Also see http://nedbatchelder.com/code/coverage/branch.html
|
|
for more details.
|
|
|
|
Install the package python-coverage to visualise your test coverage. Run the
|
|
following (note: on Debian-based systems, the script is called
|
|
`python-coverage`):
|
|
|
|
coverage run fail2ban-testcases
|
|
coverage html
|
|
|
|
Then look at htmlcov/index.html and see how much coverage your test cases
|
|
exert over the codebase. Full coverage is a good thing however it may not be
|
|
complete. Try to ensure tests cover as many independent paths through the
|
|
code.
|
|
|
|
Manual Execution. To run in a development environment do:
|
|
|
|
./fail2ban-client -c config/ -s /tmp/f2b.sock -i start
|
|
|
|
some quick commands:
|
|
|
|
status
|
|
add test pyinotify
|
|
status test
|
|
set test addaction iptables
|
|
set test actionban iptables echo <ip> <cidr> >> /tmp/ban
|
|
set test actionunban iptables echo <ip> <cidr> >> /tmp/unban
|
|
get test actionban iptables
|
|
get test actionunban iptables
|
|
set test banip 192.168.2.2
|
|
status test
|
|
|
|
|
|
|
|
Coding Standards
|
|
================
|
|
|
|
Style
|
|
-----
|
|
|
|
Please use tabs for now. Keep to 80 columns, at least for readable text.
|
|
|
|
Tests
|
|
-----
|
|
|
|
Add tests. They should test all the code you add in a meaning way.
|
|
|
|
Coverage
|
|
--------
|
|
|
|
Test coverage should always increase as you add code.
|
|
|
|
You may use "# pragma: no cover" in the code for branches of code that support
|
|
older versions on python. For all other uses of "pragma: no cover" or
|
|
"pragma: no branch" document the reason why its not covered. "I haven't written
|
|
a test case" isn't a sufficient reason.
|
|
|
|
Documentation
|
|
-------------
|
|
|
|
Ensure this documentation is up to date after changes. Also ensure that the man
|
|
pages still are accurate. Ensure that there is sufficient documentation for
|
|
your new features to be used.
|
|
|
|
Bugs
|
|
----
|
|
|
|
Remove them and don't add any more.
|
|
|
|
Git
|
|
---
|
|
|
|
Use the following tags in your commit messages:
|
|
|
|
'BF:' for bug fixes
|
|
'DOC:' for documentation fixes
|
|
'ENH:' for enhancements
|
|
'TST:' for commits concerning tests only (thus not touching the main code-base)
|
|
|
|
Multiple tags could be joined with +, e.g. "BF+TST:".
|
|
|
|
Use the text "closes #333"/"resolves #333 "/"fixes #333" where 333 represents
|
|
an issue that is closed. Other text and details in link below.
|
|
See: https://help.github.com/articles/closing-issues-via-commit-messages
|
|
|
|
If merge resulted in conflicts, clarify what changes were done to
|
|
corresponding files in the 'Conflicts:' section of the merge commit
|
|
message. See e.g. https://github.com/fail2ban/fail2ban/commit/f5a8a8ac
|
|
|
|
Adding Actions
|
|
--------------
|
|
|
|
If you add an action.d/*.conf file also add a example in config/jail.conf
|
|
with enabled=false and maxretry=5 for ssh.
|
|
|
|
|
|
Design
|
|
======
|
|
|
|
Fail2Ban was initially developed with Python 2.3 (IIRC). It should
|
|
still be compatible with Python 2.4 and such compatibility assurance
|
|
makes code ... old-fashioned in many places (RF-Note). In 0.7 the
|
|
design went through major refactoring into client/server,
|
|
a-thread-per-jail design which made it a bit difficult to follow.
|
|
Below you can find a sketchy description of the main components of the
|
|
system to orient yourself better.
|
|
|
|
server/
|
|
------
|
|
|
|
Core classes hierarchy (feel welcome to draw a better/more complete
|
|
one)::
|
|
|
|
-> inheritance
|
|
+ delegation
|
|
* storage of multiple instances
|
|
|
|
RF-Note just a note which might be useful to address while doing RF
|
|
|
|
JailThread -> Filter -> FileFilter -> {FilterPoll, FilterPyinotify, ...}
|
|
| * FileContainer
|
|
+ FailManager
|
|
+ DateDetector
|
|
+ Jail (provided in __init__) which contains this Filter
|
|
(used for passing tickets from FailManager to Jail's __queue)
|
|
Server
|
|
+ Jails
|
|
* Jail
|
|
+ Filter (in __filter)
|
|
* tickets (in __queue)
|
|
+ Actions (in __action)
|
|
* Action
|
|
+ BanManager
|
|
|
|
|
|
failmanager.py
|
|
~~~~~~~~~~~~~~
|
|
|
|
FailManager
|
|
|
|
Keeps track of failures, recorded as 'tickets'. All operations are
|
|
done via acquiring a lock
|
|
|
|
FailManagerEmpty(Exception)
|
|
|
|
raised by FailManager.toBan after reaching the list of tickets
|
|
(RF-Note: asks to become a generator ;) )
|
|
|
|
|
|
filter.py
|
|
~~~~~~~~~~
|
|
|
|
Filter(JailThread)
|
|
|
|
Wraps (non-threaded) FailManager (and proxies to it quite a bit),
|
|
and provides all primary logic for processing new lines, what IPs to
|
|
ignore, etc
|
|
|
|
.failManager [FailManager]
|
|
.dateDetector [DateDetector]
|
|
.__failRegex [list]
|
|
.__ignoreRegex [list]
|
|
Contains regular expressions for failures and ignores
|
|
.__findTime [numeric]
|
|
Used in `processLineAndAdd` to skip old lines
|
|
|
|
FileFilter(Filter):
|
|
|
|
Files-aware Filter
|
|
|
|
.__logPath [list]
|
|
keeps the tracked files (added 1-by-1 using addLogPath)
|
|
stored as FileContainer's
|
|
.getFailures
|
|
actually just returns
|
|
True
|
|
if managed to open and get lines (until empty)
|
|
False
|
|
if failed to open or absent container matching the filename
|
|
|
|
FileContainer
|
|
|
|
Adapter for a file to deal with log rotation.
|
|
|
|
.open,.close,.readline
|
|
RF-Note: readline returns "" with handler absent... shouldn't it be None?
|
|
.__pos
|
|
Keeps the position pointer
|
|
|
|
|
|
dnsutils.py
|
|
~~~~~~~~~~~
|
|
|
|
DNSUtils
|
|
|
|
Utility class for DNS and IP handling
|
|
|
|
|
|
filter*.py
|
|
~~~~~~~~~~
|
|
|
|
Implementations of FileFilter's for specific backends. Derived
|
|
classes should provide an implementation of `run` and usually
|
|
override `addLogPath`, `delLogPath` methods. In run() method they all
|
|
one way or another provide
|
|
|
|
try:
|
|
while True:
|
|
ticket = self.failManager.toBan()
|
|
self.jail.putFailTicket(ticket)
|
|
except FailManagerEmpty:
|
|
self.failManager.cleanup(MyTime.time())
|
|
|
|
thus channeling "ban tickets" from their failManager to the
|
|
corresponding jail.
|
|
|
|
action.py
|
|
~~~~~~~~~
|
|
|
|
Takes care about executing start/check/ban/unban/stop commands
|
|
|
|
|
|
Releasing
|
|
=========
|
|
|
|
# Check distribution patches and see if they can be included
|
|
|
|
* https://apps.fedoraproject.org/packages/fail2ban/sources
|
|
* http://sources.gentoo.org/cgi-bin/viewvc.cgi/gentoo-x86/net-analyzer/fail2ban/
|
|
* http://svnweb.freebsd.org/ports/head/security/py-fail2ban/
|
|
* https://build.opensuse.org/package/show?package=fail2ban&project=openSUSE%3AFactory
|
|
* http://sophie.zarb.org/sources/fail2ban (Mageia)
|
|
* https://trac.macports.org/browser/trunk/dports/security/fail2ban
|
|
|
|
# Check distribution outstanding bugs
|
|
|
|
* https://github.com/fail2ban/fail2ban/issues?sort=updated&state=open
|
|
* http://bugs.debian.org/cgi-bin/pkgreport.cgi?dist=unstable;package=fail2ban
|
|
* http://bugs.sabayon.org/buglist.cgi?quicksearch=net-analyzer%2Ffail2ban
|
|
* https://bugs.gentoo.org/buglist.cgi?query_format=advanced&short_desc=fail2ban&bug_status=UNCONFIRMED&bug_status=CONFIRMED&bug_status=IN_PROGRESS&short_desc_type=allwords
|
|
* https://bugzilla.redhat.com/buglist.cgi?query_format=advanced&bug_status=NEW&bug_status=ASSIGNED&component=fail2ban&classification=Red%20Hat&classification=Fedora
|
|
* http://www.freebsd.org/cgi/query-pr-summary.cgi?text=fail2ban
|
|
|
|
# Provide a release sample to distributors
|
|
|
|
* Debian: Yaroslav Halchenko <debian@onerussian.com>
|
|
http://packages.qa.debian.org/f/fail2ban.html
|
|
* FreeBSD: Christoph Theis theis@gmx.at>, Nick Hilliard <nick@foobar.org>
|
|
http://svnweb.freebsd.org/ports/head/security/py-fail2ban/Makefile?view=markup
|
|
* Fedora: Axel Thimm <Axel.Thimm@atrpms.net>
|
|
https://apps.fedoraproject.org/packages/fail2ban
|
|
* Gentoo: netmon@gentoo.org
|
|
http://sources.gentoo.org/cgi-bin/viewvc.cgi/gentoo-x86/net-analyzer/fail2ban/metadata.xml?view=markup
|
|
* openSUSE: Stephan Kulow <coolo@suse.com>
|
|
https://build.opensuse.org/package/users?package=fail2ban&project=openSUSE%3AFactory
|
|
* Mac Ports: @Malbrouck on github (gh-49)
|
|
https://trac.macports.org/browser/trunk/dports/security/fail2ban/Portfile
|
|
|
|
# Wait for feedback from distributors
|
|
|
|
# Ensure the version is correct in ./common/version.py
|
|
|
|
# Add/finalize the corresponding entry in the ChangeLog
|
|
|
|
To generate a list of committers use e.g.
|
|
|
|
git shortlog -sn 0.8.8.. | sed -e 's,^[ 0-9\t]*,,g' | tr '\n' '\|' | sed -e 's:|:, :g'
|
|
|
|
Ensure the top of the ChangeLog has the right version and current date.
|
|
|
|
Ensure the top entry of the ChangeLog has the right version and current date.
|
|
|
|
# Update man pages
|
|
|
|
(cd man ; ./generate-man )
|
|
git commit -m 'update man pages for release' man/*
|
|
|
|
# Make sure the tests pass
|
|
|
|
./fail2ban-testcases-all
|
|
|
|
# Prepare/upload source and rpm binary distributions
|
|
|
|
python setup.py check
|
|
python setup.py sdist
|
|
python setup.py bdist_rpm
|
|
python setup.py upload
|
|
|
|
# Run the following and update the wiki with output:
|
|
|
|
python -c 'import common.protocol; common.protocol.printWiki()'
|
|
|
|
# Email users and development list of release
|
|
|
|
# notify distributors
|
|
|
|
Post Release
|
|
============
|
|
|
|
Add the following to the top of the ChangeLog
|
|
|
|
ver. 0.8.12 (2013/XX/XXX) - wanna-be-released
|
|
-----------
|
|
|
|
- Fixes:
|
|
|
|
- New Features:
|
|
|
|
- Enhancements:
|
|
|
|
|
|
and adjust common/version.py to carry .dev suffix to signal
|
|
a version under development.
|