Apache2 - Mod_bw v0.7 Author : Ivan Barrera A. (Bruce) HomePage : Http://Ivn.cl/apache & http://bwmod.sf.net Release Date : 01-09-2005 Status : Functional. Tested under medium and heavy load. License : Licensed under the Apache Software License v2.0 It must be included as LICENSE in this package. Platform : Linux/x86 (Tested with Fedora Core 4, Suse, etc) FreeBSD/x86 (Tested on 5.2) MacOS X/Ppc x86 (Tested on both platforms) Solaris 8/sparc (Some notes on compile) Microsoft Windows (Win XP, Win2003. Others should work) Notes : This is a stable version of mod_bw. It works fine with almost any MPM (tested with WinNT/prefork/Worker MPM). Limitations : This mod doesn't know how fast is the client really downloading a file, so it just divides the bw assigned between the users. MaxConnections works only for the given scope. (i.e , all will limit maxconnections from all,not per ip or user) Especials thanks goes to the "Summer Of Code 2005" program of Google! Chris DiBona and all the team, who were helping us out since the beggining. Thanks to Ian Holsman and Paul Querna, Mentors from Apache Foundation. ------------------------------------------------------------------------------ Contents : 1 .- Notices 1.1 - Summer Of Code Program 1.2 - ChangeLog and TODO 2 .- Installing 2.1 - Windows 2.2 - Linux 3 .- Getting it to Work, Directives 3.1 - BandWidthModule 3.2 - ForceBandWidthModule 3.3 - BandWidth 3.4 - MinBandWidth 3.5 - LargeFileLimit 3.6 - BandWidthPacket 3.7 - BandWidthError 3.8 - MaxConnection 4 .- Examples 4.1 - Misc Examples 5 .- FAQ ------------------------------------------------------------------------------ 1.- Notices 1.1 - Summer Of Code Program : Google launch Summer Of Code 2005 program, to motivate the development of open source software. Many students around the world signed on the program in differents areas/projects. Mine has to do with Bandwidth limiting in current Apache webserver. The main idea behind the program, is to incentivate the development of quality open source program, offering a grant in ------------------------------------------------------------------------------ 1.2 - ChangeLog & TODO : This has been moved to the files ChangeLog and TODO. Available on the packages and CVS at SourceForge. ------------------------------------------------------------------------------ 2.- How To Install : 2.1 - Windows In Windows, you have to download the binary dll from the site (or compile one yourself) that matches your apache version, and Install it under modules on your apache tree. Then edit httpd.conf, and add the LoadModule sentence. If there is no matching binary dll with your version of apache (the latest) you can ask me to compile it for you. Post a message in the home site as a feature request. Example : Download mod_bw-2.0.54.dll from the home site, to c:\apache2\modules Edit httpd.conf, and add LoadModule bw_module modules/mod_bw-2.0.54.dll Restart Apache. 2.2 - Linux Well.. (under *nix) you *have* to compile it.. It might sound scary, but it's easy. There is an easy way, and the hard way. If the easy way doesn't work for you, use the hard way. REQUIREMENTS : You will need apache2 headers in the include path. In redhat/suse or others this mean apache-devel or httpd-devel installed. You also need support for SHM in your OS. Usually you will have this. - Easy Way : For this to work, you MUST have apxs (or apxs2) installed. You might need to use it full path (i.e. /usr/sbin/apxs .....). Well, you have to do this : apxs -i -a -c mod_bw.c or apxs2 -i -a -c mod_bw.c This will bring out some stuff... nothing to worry (unless you see error) If it says ok, then you are ready. Restart apache (service apache restart on redhat, mandrake, and others... apachectl restart .. rcapache2 restart or... well, you should know) Note On Solaris Users : If you got problems compiling it on Solaris, remember to check you have libgcc correctly installed, and the ld_library_path set up correctly. I didnt, so i compiled this way : export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/usr/local/lib apxs -i -a -c mod_bw.c -L/usr/local/lib -lgcc_s And then started apache, and everything worked fine. Note On SuSe Users : You NEED to have installed apache2 header files (apache2-devel rpm). Otherwise you'll get lots of include files error. - Hard Way If using the easy way, you turned to have some .o files.. you are almost done... skip to the part of installing the module. Back to the hard way..... you might notice that you dont have apxs, dont know why (maybe the dog ate it). Well. try the following (and please do it on a newly-fresh created directory for this purpose) : (this does not necessarily work on all cases) libtool --silent --mode=compile gcc -g -O2 -pthread -DLINUX=2 \ -D_REENTRANT -D_XOPEN_SOURCE=500 -D_BSD_SOURCE -D_SVID_SOURCE \ -I/usr/include/httpd \ -I/usr/include/apr-0 -Wall -g\ -prefer-pic -c mod_bw.c && touch mod_bw.slo libtool --silent --mode=link gcc -g -O2 -pthread -DLINUX=2 \ -D_REENTRANT -D_XOPEN_SOURCE=500 -D_BSD_SOURCE -D_SVID_SOURCE \ -D_GNU_SOURCE -DAP_HAVE_DESIGNATED_INITIALIZER \ -I/usr/include/httpd \ -I/usr/include/apr-0 -Wall -g\ -export-dynamic -o mod_bw.la -rpath /usr/lib/httpd/modules \ -module -avoid-version mod_bw.lo (this cleans some unneeded files) rm -rf *.a *.la *.lo *.slo *.o *.loT mv .libs/*.so . rm -rf .libs Note that you need to know where are your httpd and apr includes. (dont ask me where they are.. you are supossed to know) If this worked... we are good to install the module. * Installing the module (hey.. this is part of the hard way) Ok, either if the easy way didnt install the mod, or if you did the hard way, now you must install the module by hand. Is easy as copying the file (usually mod_bw.so) to the apache modules directory (usually /etc/httpd/modules or /usr/local/libexec/apache2/) and then adding the following line at httpd.conf (better of if you add it at the last part of all LoadModule sentences) : LoadModule bw_module mod_bw.so Please, take a look at the other LoadModule sentences. You may need to add a path before the .so file. (i.e LoadModule bw_module libexec/apache2/mod_bw.so) If you didn't manage to get it installed, drop me a letter. But please be sure you tried everything. Sometimes the simplest way, is the better. ------------------------------------------------------------------------------ 3.- Getting it to Work : Ok.. this is the most confusing part. (yeh, most of us think the installing part is the hardest xD ) This mod, is able to limit bandwidth usage on every virtual host or directory. htaccess files are not supported yet, cause i've been having some serious segfaults when implementing it. * Configuration Directives ***************************************************************************** 3.1 - BandWidthModule [On|Off] You need to set this to On, for the mod to work.. By default, the mod is disabled, and wont limit anything. Example : BandWidthModule On 3.2 - ForceBandWidthModule [On|Off] By default, the mod wont catch every request. If you enable it, every request will be processed by the mod. Example : (normal use) AddOutputFilterByType MOD_BW text/html text/plain (enabling Force) ForceBandWidthModule On 3.3 - BandWidth [From] [bytes/s] This takes 2 parameters. From is the origin of the connections. It could be a full host, part of a domain, an ip address, a network mask (i.e 192.168.0.0/24 or 192.168.0.0/255.255.255.0) or all. The second parameter indicates the total speed available to the Origin. If speed is 0, there is no limit. Example : BandWidth localhost 10240 BandWidth 192.168.218.5 0 ( Order is relevant. First entries have precedence ) 3.4 - MinBandWidth [From] [bytes/s] This takes 2 parameters. From is the origin of the connections. It could be a full host, part of a domain, an ip address, a network mask (i.e 192.168.0.0/24 or 192.168.0.0/255.255.255.0) or all. The second parameter indicates the minimun speed each client will have. What does this mean ? If you have a total of 100kbytes speed, and you put MinBandWidth at 50kbytes, it doesnt matter how many clients you have, all of them will have at minimun 50kbytes of total speed to download. If speed is 0, you will be using the default minimun (256 bytes/s). There is a special value of -1. This value means that each client, will have a top speed determined by the BandWidth directive. See the examples. Examples : BandWidth all 102400 MinBandWidth all 50000 The example above, will have a top speed of 100kb for the 1º client. If more clients come, it will be splitted accordingly but everyone will have at least 50kb (even if you have 50 clients) BandWidth all 50000 MinBandWidth all -1 This example, makes everyone have 50kb as top speed. 3.5 - LargeFileLimit [Type] [Minimum Size] [bytes/s] Type, is the last part of a file, or * for all. You can use .tgz to match only tar-compressed files, .avi to match video files, or * to match all. Minimum Size, is the size (in kbytes) of the file, to be matched. That way you can match huge video files that hog your bandwidth. The last parameter... is obvious. The speed allowed. Example : LargeFileLimit .avi 500 10240 This limits .avi files over (or equal to) 500kb to 10kbytes/s 3.6 - BandWidthPacket [Size] Probably you never need to touch this. It defaults to 8192 which is good for almost any speed. It must be a size between 1024 and 131072. A Small packet will cause the top speed to be lower, and the mod using more time splitting. If you use a Size too big, the mod will adjust it to lower speeds. 3.7 - BandWidthError [Error] This directives is useful to deliver a personalized error code. At default, when maxconnections is reached, the mod will issue a 503 HTTP_SERVICE_UNAVAILABLE code. For some users, it is annoying to have an error message, and dont knowing why. You could use an ErrorDocument to point error 503 to a page explaining that you are under a heavy load of connections, but sometimes 503 isn't issued by the mod. So, with this directive, you can set the error code to return when maxconnections is reached. You can use any error code between 300 and 599. Please note, that some of the error codes are already used, so before using any number, take a look to a list of the codes (search for http error codes in google). When testing, i've used the error code 510, which hasn't been defined yet. And Example, with Personalized Error Page : ErrorDocument 510 /errors/maxconexceeded.html BandWidthError 510 Note : Sometimes, the personalized page didn't appear. I'm not sure, but in many cases, it got fixed, by making the page size over 1024bytes. Anyways, if you need help using ErrorDocument, refer to the apache Documentation. 3.8 - MaxConnection [From] [Max] This takes 2 parameters. From is the origin of the connections. It could be a full host, part of a domain, an ip address, a network mask (i.e 192.168.0.0/24 or 192.168.0.0/255.255.255.0) or all. The second parameter, is the max connections allowed from the origin. Any connection over Max, will get a 503 Service Temporarily Unavailable There is a catch. You NEED to have a BandWidth limit for the same origin. It doesnt need to be a low limit. You can use an unlimited setting. You might wonder why. It's because im using them same memory space of the bandwidth limit, to count the connections, so i can save memory space. If you dont put a BandWidth using the same origin, MaxConnections will be ignored. Example : BandWidth all 0 MaxConnection all 20 or BandWidth all 0 BandWidth 192.168.0.0/24 10240 MaxConnection all 20 MaxConnection 192.168.0.0/24 5 Please, rememeber that every speed, will depend mostly on your connection. You cant get more speed if you dont have it. Remember also.. if you dont follow the instructions, and get some weird results, recheck your config before sending me an email. ------------------------------------------------------------------------------ 4.- Examples 4.1 - Misc examples Limit every user to a max of 10Kb/s on a vhost : BandwidthModule On ForceBandWidthModule On Bandwidth all 10240 MinBandwidth all -1 Servername www.example.com Limit al internal users (lan) to 1000 kb/s with a minimum of 50kb/s , and files greater than 500kb to 50kb/s. BandwidthModule On ForceBandWidthModule On Bandwidth all 1024000 MinBandwidth all 50000 LargeFileLimit * 500 50000 Servername www.example.com Limit avi and mpg extensions to 20kb/s. BandwidthModule On ForceBandWidthModule On LargeFileLimit .avi 1 20000 LargeFileLimit .mpg 1 20000 Servername www.example.com Using it the "right" way, with output filter by mime type (for text) to 5kb/s: BandwidthModule On AddOutputFilterByType MOD_BW text/html text/plain Bandwidth all 5000 Servername www.example.com If you need help on doing more complex setup, you could post it in sf.net forums. ------------------------------------------------------------------------------ 5.- FAQ (No particular order) 1.- Why should i use mod_bw ? If you want to restrict the top speed a site is able to use, or limit the max connections allowed per site, or just to try the mod. Some people told me, they use it primarily to stop small sites hogging all the bandwidth when serving video, images, or other content. 2.- How do i ... ? First, read the documentation. it is pretty straightforward to use. If you can't make it work, or if you want to ask for a feature, visit the home site, and post a request. Remember to read the documentation and the faq. If the request is already posted, i'll just delete the duplicates. 3.- What's the difference with mod_bwshare, mod_throttle, etc ? The main difference, is that this mod, is aimed to the Apache 2 API. Some other differences, is, how this mod works, and the directives it implements. I took some ideas from other mods, as the shared memory implementation (mod_bandwidth2 from Tim Verhoeven). Most of the directives, are in origin from mod_bandiwdth for apache 1. 4.- How does it works ? The mod, will set a shared memory holding all of the configuration you make. In this space, it will also, keep a "count" of the info currently using (as current connections, bw used, time, and bytes sent). When you assign a bw limit, the mod will "split" the data, and will send it piece by piece, with a small delay between pieces. The delay will be adjusted so at least 1 piece is sent in a second, thus eviting browser timeout. If there are two or more clients downloading from the same vhost, the limit will be "splitted" too. So, if you have a bw limit of 16Kb and two clients, each one will have 8Kb to download. You can also set a fixed download rate, so each client will have a fixed maximun download rate. This is a simple explanation of how this works. Take a look at the code if you want to know more about it. 5.- Can you make it do ... ? Post a request for a feature in the home site. I'll respond there. 6.- Can you make mod_bw work for ... ? See question 5. Anyways, if i dont own (or have access) to the hardware needed, i won't be able to help you. 7.- I'm having some trouble in windows ... I cannot support windows in an official way. I do not own a licensed copy of Windows, or Visual C. Anyways, post your problem in the home site. 8.- The mod is not limiting certain Directory Ok... first, read the documentation. Then the FAQ. If it isn't working, then look if you have defined correctly the limits within that directory. If you have a limit in a vhost, and inside the vhost, a directory with another limit, a new context with the configs of the directory is created, and only have the configurations you added there. In example : BandWidthModule On BandWidth all 16384 LargeFileLimit * 500 4096 LargeFileLimit * 100 1024 This wont limit Directory / to 16384. The Directory wont "inherit" the settings from the vhost if you use some of the mod's directives. ------------------------------------------------------------------------------ Ivan Barrera A. Ivn Systems Software -(Bruce@Ivn.cl)-