mod-evasive apache

/etc/apache2/conf.d# more mod-evasive.conf DOSHashTableSize 3097 DOSPageCount 13 DOSSiteCount 50 DOSPageInterval 1 DOSSiteInterval 1 DOSBlockingPeriod 15 DOSLogDir /tmp DOSWhitelist 127.0.0.1 aquest son els valors que menys problemes ens donen per treballar en local, i amb moodle i eines com prestashop i joomla que fan moltes peticions per web..... a2enmod mod-evasive Module mod-evasive already enabled administrator@ubuntu:~$ sudo /etc/init.d/apache2 restart * Restarting web server apache2 de fer la prova amb f5 obtenim al fitxer error.log d'apache [Fri May 10 01:38:48 2013] [error] [client 192.168.2.252] client denied by server configuration: /srv/www/moodle2/ [Fri May 10 01:38:48 2013] [error] [client 192.168.2.252] client denied by server configuration: /var/cache/munin/www/localdomain/localhost.localdomain/apache_volume-week.png, referer: http://ies-sabadell.cat/munin/localdomain/localhost.localdomain/index.html i al directori /tmp /tmp# ls -la -rw-r--r-- 1 www-data www-data 5 may 10 01:38 dos-188.77.249.218 -rw-r--r-- 1 www-data www-data 5 may 9 10:13 dos-192.168.0.228 -rw-r--r-- 1 www-data www-data 5 may 7 13:12 dos-192.168.1.240 -rw-r--r-- 1 www-data www-data 6 may 8 10:10 dos-192.168.1.244 -rw-r--r-- 1 www-data www-data 5 may 7 13:23 dos-192.168.128.239 -rw-r--r-- 1 www-data www-data 5 may 7 18:51 dos-192.168.128.89 -rw-r--r-- 1 www-data www-data 6 may 7 13:51 dos-192.168.129.181 -rw-r--r-- 1 www-data www-data 6 may 7 16:46 dos-192.168.129.208 -rw-r--r-- 1 www-data www-data 6 may 8 08:34 dos-192.168.129.222 -rw-r--r-- 1 www-data www-data 6 may 8 10:01 dos-192.168.129.53 -rw-r--r-- 1 www-data www-data 6 may 7 13:54 dos-192.168.129.78 -rw-r--r-- 1 www-data www-data 6 may 9 12:01 dos-192.168.130.34 -rw-r--r-- 1 www-data www-data 6 may 8 11:56 dos-192.168.130.41 -rw-r--r-- 1 www-data www-data 5 may 10 01:38 dos-192.168.2.252 -rw-r--r-- 1 www-data www-data 5 may 10 01:39 dos-79.151.132.218 http://www.electromech.info/linux-apache-mod-evasive-module-howto.html WHAT IS MOD_EVASIVE ? mod_evasive is an evasive maneuvers module for Apache to provide evasive action in the event of an HTTP DoS or DDoS attack or brute force attack. It is also designed to be a detection tool, and can be easily configured to talk to ipchains, firewalls, routers, and etcetera. Detection is performed by creating an internal dynamic hash table of IP Addresses and URIs, and denying any single IP address from any of the following: - Requesting the same page more than a few times per second - Making more than 50 concurrent requests on the same child per second - Making any requests while temporarily blacklisted (on a blocking list) This method has worked well in both single-server script attacks as well as distributed attacks, but just like other evasive tools, is only as useful to the point of bandwidth and processor consumption (e.g. the amount of bandwidth and processor required to receive/process/respond to invalid requests), which is why it's a good idea to integrate this with your firewalls and routers. This module instantiates for each listener individually, and therefore has a built-in cleanup mechanism and scaling capabilities. Because of this, legitimate requests are rarely ever compromised, only legitimate attacks. Even a user repeatedly clicking on 'reload' should not be affected unless they do it maliciously. Three different module sources have been provided: Apache v1.3 API: mod_evasive.c Apache v2.0 API: mod_evasive20.c HOW IT WORKS A web hit request comes in. The following steps take place: - The IP address of the requestor is looked up on the temporary blacklist - The IP address of the requestor and the URI are both hashed into a "key". A lookup is performed in the listener's internal hash table to determine if the same host has requested this page more than once within the past 1 second. - The IP address of the requestor is hashed into a "key". A lookup is performed in the listerner's internal hash table to determine if the same host has requested more than 50 objects within the past second (from the same child). If any of the above are true, a 403 response is sent. This conserves bandwidth and system resources in the event of a DoS attack. Additionally, a system command and/or an email notification can also be triggered to block all the originating addresses of a DDoS attack. Once a single 403 incident occurs, mod_evasive now blocks the entire IP address for a period of 10 seconds (configurable). If the host requests a page within this period, it is forced to wait even longer. Since this is triggered from requesting the same URL multiple times per second, this again does not affect legitimate users. The blacklist can/should be configured to talk to your network's firewalls and/or routers to push the attack out to the front lines, but this is not required. mod_evasive also performs syslog reporting using daemon.alert. Messages will look like this: Aug 6 17:41:49 elijah mod_evasive[23184]: [ID 801097 daemon.alert] Blacklisting address x.x.x.x: possible attack. WHAT IS THIS TOOL USEFUL FOR? This tool is *excellent* at fending off request-based DoS attacks or scripted attacks, and brute force attacks. When integrated with firewalls or IP filters, mod_evasive can stand up to even large attacks. Its features will prevent you from wasting bandwidth or having a few thousand CGI scripts running as a result of an attack. If you do not have an infrastructure capable of fending off any other types of DoS attacks, chances are this tool will only help you to the point of your total bandwidth or server capacity for sending 403's. Without a solid infrastructure and address filtering tool in place, a heavy distributed DoS will most likely still take you offline. Howto Install on Apache 2.X [root@station100 ~]# rpm -q httpd httpd-2.2.3-31.el5 First download it from internet or given location. [root@station100 ~]# wget http://www.zdziarski.com/blog/wp-content/uploads/2010/02/mod_evasive_1.10.1.tar.gz [root@station100 ~]# cp mod_evasive_1.10.1.tar.gz /tmp/ [root@station100 ~]# cd /tmp/ [root@station100 tmp]# tar -zxf mod_evasive_1.10.1.tar.gz [root@station100 tmp]# cd mod_evasive [root@station100 mod_evasive]# ls CHANGELOG Makefile.tmpl mod_evasive.c README LICENSE mod_evasive20.c mod_evasiveNSAPI.c test.pl [root@station100 mod_evasive]# ls CHANGELOG Makefile.tmpl mod_evasive.c README LICENSE mod_evasive20.c mod_evasiveNSAPI.c test.pl [root@station100 mod_evasive]# locate apxs /usr/sbin/apxs /usr/share/man/man8/apxs.8.gz /var/www/manual/programs/apxs.html /var_old/www/manual/programs/apxs.html [root@station100 mod_evasive]# /usr/sbin/apxs -i -a -c mod_evasive20.c /usr/lib/apr-1/build/libtool --silent --mode=compile gcc -prefer-pic -O2 -g -pipe -Wall -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector --param=ssp-buffer-size=4 -m32 -march=i386 -mtune=generic -fasynchronous-unwind-tables -fno-strict-aliasing -DLINUX=2 -D_REENTRANT -D_GNU_SOURCE -D_LARGEFILE64_SOURCE -pthread -I/usr/include/httpd -I/usr/include/apr-1 -I/usr/include/apr-1 -c -o mod_evasive20.lo mod_evasive20.c && touch mod_evasive20.slo mod_evasive20.c: In function 'access_checker': mod_evasive20.c:212: warning: implicit declaration of function 'getpid' mod_evasive20.c:212: warning: format '%ld' expects type 'long int', but argument 4 has type 'int' mod_evasive20.c:229: warning: ignoring return value of 'system', declared with attribute warn_unused_result mod_evasive20.c: In function 'destroy_hit_list': mod_evasive20.c:301: warning: control reaches end of non-void function mod_evasive20.c: In function 'create_hit_list': mod_evasive20.c:118: warning: control reaches end of non-void function /usr/lib/apr-1/build/libtool --silent --mode=link gcc -o mod_evasive20.la -rpath /usr/lib/httpd/modules -module -avoid-version mod_evasive20.lo /usr/lib/httpd/build/instdso.sh SH_LIBTOOL='/usr/lib/apr-1/build/libtool' mod_evasive20.la /usr/lib/httpd/modules /usr/lib/apr-1/build/libtool --mode=install cp mod_evasive20.la /usr/lib/httpd/modules/ cp .libs/mod_evasive20.so /usr/lib/httpd/modules/mod_evasive20.so cp .libs/mod_evasive20.lai /usr/lib/httpd/modules/mod_evasive20.la cp .libs/mod_evasive20.a /usr/lib/httpd/modules/mod_evasive20.a chmod 644 /usr/lib/httpd/modules/mod_evasive20.a ranlib /usr/lib/httpd/modules/mod_evasive20.a PATH="$PATH:/sbin" ldconfig -n /usr/lib/httpd/modules ---------------------------------------------------------------------- Libraries have been installed in: /usr/lib/httpd/modules If you ever happen to want to link against installed libraries in a given directory, LIBDIR, you must either use libtool, and specify the full pathname of the library, or use the `-LLIBDIR' flag during linking and do at least one of the following: - add LIBDIR to the `LD_LIBRARY_PATH' environment variable during execution - add LIBDIR to the `LD_RUN_PATH' environment variable during linking - use the `-Wl,--rpath -Wl,LIBDIR' linker flag - have your system administrator add LIBDIR to `/etc/ld.so.conf' See any operating system documentation about shared libraries for more information, such as the ld(1) and ld.so(8) manual pages. ---------------------------------------------------------------------- chmod 755 /usr/lib/httpd/modules/mod_evasive20.so [activating module `evasive20' in /etc/httpd/conf/httpd.conf] [root@station100 mod_evasive]# [root@station100 mod_evasive]# ls /usr/lib/httpd/modules/ libmodnss.so mod_cgid.so mod_logio.so libphp5.so mod_cgi.so mod_mem_cache.so mod_actions.so mod_dav_fs.so mod_mime_magic.so mod_alias.so mod_dav.so mod_mime.so mod_asis.so mod_dbd.so mod_negotiation.so mod_auth_basic.so mod_deflate.so mod_perl.so mod_auth_digest.so mod_dir.so mod_proxy_ajp.so mod_authn_alias.so mod_disk_cache.so mod_proxy_balancer.so mod_authn_anon.so mod_dumpio.so mod_proxy_connect.so mod_authn_dbd.so mod_env.so mod_proxy_ftp.so mod_authn_dbm.so mod_evasive20.so mod_proxy_http.so mod_authn_default.so mod_expires.so mod_proxy.so mod_authn_file.so mod_ext_filter.so mod_rewrite.so mod_authnz_ldap.so mod_file_cache.so mod_setenvif.so mod_authz_dbm.so mod_filter.so mod_speling.so mod_authz_default.so mod_headers.so mod_ssl.so mod_authz_groupfile.so mod_ident.so mod_status.so mod_authz_host.so mod_imagemap.so mod_suexec.so mod_authz_owner.so mod_include.so mod_unique_id.so mod_authz_user.so mod_info.so mod_userdir.so mod_autoindex.so mod_ldap.so mod_usertrack.so mod_cache.so mod_log_config.so mod_version.so mod_cern_meta.so mod_log_forensic.so mod_vhost_alias.so [root@station100 mod_evasive]# CONFIGURATION mod_evasive has default options configured, but you may also add the following block to your httpd.conf: APACHE v1.3 ----------- DOSHashTableSize 3097 DOSPageCount 2 DOSSiteCount 50 DOSPageInterval 1 DOSSiteInterval 1 DOSBlockingPeriod 10 APACHE v2.0 ----------- DOSHashTableSize 3097 DOSPageCount 2 DOSSiteCount 50 DOSPageInterval 1 DOSSiteInterval 1 DOSBlockingPeriod 10 DOSHashTableSize ---------------- The hash table size defines the number of top-level nodes for each child's hash table. Increasing this number will provide faster performance by decreasing the number of iterations required to get to the record, but consume more memory for table space. You should increase this if you have a busy web server. The value you specify will automatically be tiered up to the next prime number in the primes list (see mod_evasive.c for a list of primes used). DOSPageCount ------------ This is the threshhold for the number of requests for the same page (or URI) per page interval. Once the threshhold for that interval has been exceeded, the IP address of the client will be added to the blocking list. DOSSiteCount ------------ This is the threshhold for the total number of requests for any object by the same client on the same listener per site interval. Once the threshhold for that interval has been exceeded, the IP address of the client will be added to the blocking list. DOSPageInterval --------------- The interval for the page count threshhold; defaults to 1 second intervals. DOSSiteInterval --------------- The interval for the site count threshhold; defaults to 1 second intervals. DOSBlockingPeriod ----------------- The blocking period is the amount of time (in seconds) that a client will be blocked for if they are added to the blocking list. During this time, all subsequent requests from the client will result in a 403 (Forbidden) and the timer being reset (e.g. another 10 seconds). Since the timer is reset for every subsequent request, it is not necessary to have a long blocking period; in the event of a DoS attack, this timer will keep getting reset. DOSEmailNotify -------------- If this value is set, an email will be sent to the address specified whenever an IP address becomes blacklisted. A locking mechanism using /tmp prevents continuous emails from being sent. NOTE: Be sure MAILER is set correctly in mod_evasive.c (or mod_evasive20.c). The default is "/bin/mail -t %s" where %s is used to denote the destination email address set in the configuration. If you are running on linux or some other operating system with a different type of mailer, you'll need to change this. DOSSystemCommand ---------------- If this value is set, the system command specified will be executed whenever an IP address becomes blacklisted. This is designed to enable system calls to ip filter or other tools. A locking mechanism using /tmp prevents continuous system calls. Use %s to denote the IP address of the blacklisted IP. DOSLogDir --------- Choose an alternative temp directory By default "/tmp" will be used for locking mechanism, which opens some security issues if your system is open to shell users. http://security.lss.hr/index.php?page=details&ID=LSS-2005-01-01 In the event you have nonprivileged shell users, you'll want to create a directory writable only to the user Apache is running as (usually root), then set this in your httpd.conf. WHITELISTING IP ADDRESSES IP addresses of trusted clients can be whitelisted to insure they are never denied. The purpose of whitelisting is to protect software, scripts, local searchbots, or other automated tools from being denied for requesting large amounts of data from the server. Whitelisting should *not* be used to add customer lists or anything of the sort, as this will open the server to abuse. This module is very difficult to trigger without performing some type of malicious attack, and for that reason it is more appropriate to allow the module to decide on its own whether or not an individual customer should be blocked. To whitelist an address (or range) add an entry to the Apache configuration in the following fashion: DOSWhitelist 127.0.0.1 DOSWhitelist 127.0.0.* Wildcards can be used on up to the last 3 octets if necessary. Multiple DOSWhitelist commands may be used in the configuration. -- So we will add our network as whitelist ip #our network is 192.168.2.0/24 DOSWhitelist 127.0.0.1 DOSWhitelist 192.168.2.* So finally our entry in httpd.conf is #mod_evasive20 configuration start here------- DOSHashTableSize 3097 DOSPageCount 2 DOSSiteCount 50 DOSPageInterval 1 DOSSiteInterval 1 DOSBlockingPeriod 10 #our network is 192.168.2.0/24 DOSWhitelist 127.0.0.1 DOSWhitelist 192.168.2.* #mod_evasive20 configuration end here-------- Let us restart the service [root@station100 ~]# /etc/init.d/httpd restart Stopping httpd: [ OK ] Starting httpd: [ OK ] [root@station100 ~]# Before running final test ... What is mod_evasive? mod_evasive is an evasive maneuvers module for Apache to provide evasive action in the event of an HTTP DoS or DDoS attack or brute force attack. It is also designed to be a detection and network management tool, and can be easily configured to talk to ipchains, firewalls, routers, and etcetera. mod_evasive presently reports abuses via email and syslog facilities. Detection is performed by creating an internal dynamic hash table of IP Addresses and URIs, and denying any single IP address from any of the following: Requesting the same page more than a few times per second Making more than 50 concurrent requests on the same child per second Making any requests while temporarily blacklisted (on a blocking list) This method has worked well in both single-server script attacks as well as distributed attacks, but just like other evasive tools, is only as useful to the point of bandwidth and processor consumption (e.g. the amount of bandwidth and processor required to receive/process/respond to invalid requests), which is why it’s a good idea to integrate this with your firewalls and routers for maximum protection. This module instantiates for each listener individually, and therefore has a built-in cleanup mechanism and scaling capabilities. Because of this per-child design, legitimate requests are never compromised (even from proxies and NAT addresses) but only scripted attacks. Even a user repeatedly clicking on ‘reload’ should not be affected unless they do it maliciously. mod_evasive is fully tweakable through the Apache configuration file, easy to incorporate into your web server, and easy to use.