THE CLICK MODULAR ROUTER========================    This is the README file for the source release for the Click modularsoftware router. More recent information may be available on the Web athttp://www.read.cs.ucla.edu/click/    Click is a modular router toolkit. To use it you'll need to know how tocompile and install the software, how to write router configurations, andhow to write new elements. Our ACM Transactions on Computer Systems paper,available from the Web site, will give you a feeling for what Click cando. Using the optimization tools under CLICKDIR/tools, you can get evenbetter performance than that paper describes.CONTENTS--------CLICKDIRthis directoryCLICKDIR/appsClick-related applicationsCLICKDIR/apps/clicky... GTK program for displaying configurations    and interacting with driversCLICKDIR/apps/ClickController... Java program for interacting with driversCLICKDIR/bsdmoduleFreeBSD 4.5 kernel module driver [NOT WORKING]CLICKDIR/confconfiguration filesCLICKDIR/docdocumentationCLICKDIR/driverspolling device driversCLICKDIR/elementselement source codeCLICKDIR/elements/analysis... for trace analysis and manipulationCLICKDIR/elements/app... for application-level protocol elementsCLICKDIR/elements/aqm... for active queue management (RED, etc.)CLICKDIR/elements/bsdmodule... for FreeBSD kernel-specific elementsCLICKDIR/elements/ethernet... for Ethernet elementsCLICKDIR/elements/etherswitch... for Ethernet-switch elementsCLICKDIR/elements/grid... for Grid elements (experimental)CLICKDIR/elements/icmp... for ICMP elementsCLICKDIR/elements/ip... for IP, ICMP, and TCP/UDP elementsCLICKDIR/elements/ip6... for IPv6 elementsCLICKDIR/elements/ipsec... for IPsec elementsCLICKDIR/elements/linuxmodule... for Linux kernel-specific elementsCLICKDIR/elements/local... for your own elements (empty)CLICKDIR/elements/ns... for 'ns'-specific elementsCLICKDIR/elements/radio... for communicating with wireless radiosCLICKDIR/elements/standard... for generic elementsCLICKDIR/elements/tcpudp... for TCP and UDP elementsCLICKDIR/elements/test... for regression test elementsCLICKDIR/elements/threads... for thread management elementsCLICKDIR/elements/userlevel... for user-level-specific elementsCLICKDIR/elements/wifi        ... for 802.11-specific 'WiFi' elementsCLICKDIR/etcLinux and NS patches and other filesCLICKDIR/etc/samplepackagesample source code for Click element packageCLICKDIR/etc/samplellrpcsample source code for reading Click LLRPCsCLICKDIR/etc/diagramsfiles for drawing Click diagramsCLICKDIR/etc/libclickfiles for standalone user-level Click libraryCLICKDIR/include/clickcommon header filesCLICKDIR/include/clicknetheader files defining network headersCLICKDIR/libcommon non-element source codeCLICKDIR/linuxmoduleLinux kernel module driverCLICKDIR/ns'ns' driver (integrates with the ns simulator)CLICKDIR/testregression testsCLICKDIR/toolsClick toolsCLICKDIR/tools/lib... common code for toolsCLICKDIR/tools/click-align... handles alignment for non-x86 machinesCLICKDIR/tools/click-combine... merges routers into combined configurationCLICKDIR/tools/click-devirtualize   ... removes virtual functions from sourceCLICKDIR/tools/click-fastclassifier ... specializes Classifiers into C++ codeCLICKDIR/tools/click-mkmindriver    ... build environments for minimal driversCLICKDIR/tools/click-install... installs configuration into kernel moduleCLICKDIR/tools/click-pretty... pretty-prints Click configuration as HTMLCLICKDIR/tools/click-undead... removes dead code from configurationsCLICKDIR/tools/click-xform... pattern-based configuration optimizerCLICKDIR/tools/click2xml... convert Click language <-> XMLCLICKDIR/userleveluser-level 'click' driverDOCUMENTATION-------------    The 'INSTALL' file in this directory contains installationinstructions. User documentation is in the 'doc' subdirectory. Thisdirectory contains manual pages for the Click language, the Linux kernelmodule, and several tools; it also has a script that generates manual pagesfor many of the elements distributed in this package. To install thesemanual pages so you can read them, follow the 'INSTALL' instructions, but'make install-man' instead of 'make install'.RUNNING A CLICK ROUTER----------------------    Before playing with a Click router, you should get familiar with theClick configuration language. You use this to tell Click how to processpackets. The language describes a graph of "elements", or packet processingmodules. See the 'doc/click.5' manual page for a detailed description, orcheck the 'conf' directory for some simple examples.    Click can be compiled as a user-level program or as a kernel module forLinux. Either driver can receive and send packets; the kernel moduledirectly interacts with device drivers, while the user-level driver usespacket sockets (on Linux) or the pcap library (everywhere else).User-Level Program..................    Run the user-level program by giving it the name of a configurationfile: 'click CONFIGFILE'.Linux Kernel Module...................    See the 'doc/click.o.8' manual page for a detailed description. Tosummarize, install a configuration by running 'click-install CONFIGFILE'.This will also install the kernel module if necessary and report any errorsto standard error. (You must run 'make install' before 'click-install' willwork.)NS-3 Simulator..............    See 'INSTALL' for more information on how to enable the NS-3 ClickIntegration. Further information on ns-3-click is available in the ns-3manual:http://www.nsnam.org/docs/models/html/click.htmlNS-2 Simulator..............    See 'INSTALL' for more information.  Once a Click-enabled version of NS-2is installed, the 'ns' command is able to run Click scripts as part of anormal NS-2 simulation.Configurations..............    A few configurations are included in the 'conf' directory, including aPerl script that generated the IP router configurations used in our TOCSpaper ('conf/make-ip-conf.pl') and a set of patterns for the Click patternoptimizer, click-xform ('conf/ip.clickpat'). Please check back to our Website for more up-to-date configurations.ADDING YOUR OWN ELEMENTS------------------------    Please see the FAQ in this directory to learn how to add elements toClick.COPYRIGHT AND LICENSE---------------------    Most of Click is distributed under the Click license, a version ofthe MIT License. See the 'LICENSE' file for details. Each source fileshould identify its license. Source files that do not identify aspecific license are covered by the Click license.    Parts of Click are distributed under different licenses. Thespecific licenses are listed below.    drivers/e1000*, etc/linux-*-patch, linuxmodule/proclikefs.c: Theseportions of the Click software are derived from the Linux kernel, andare thus distributed under the GNU General Public License, version 2.The GNU General Public License is available via the Web at<http://www.gnu.org/licenses/gpl.html>, or in the COPYING file in thisdirectory.    include/click/bigint.hh: This portion of the Click softwarederives from the GNU Multiple Precision Arithmetic Library, and isthus distributed under the GNU Lesser General Public License, version3. This license is available via the Web at<http://www.gnu.org/licenses/lgpl.html>. The LGPL specifically permitsdirect linking with code with other licenses.    Element code that uses only Click's interfaces will *not* bederived from the Linux kernel. (For instance, those interfaces havemultiple implementations, including some that run at user level.)Thus, for element code that uses only Click's interfaces, the BSD-likeClick license applies, not the GPL or the LGPL.BUGS, QUESTIONS, ETC.---------------------    We welcome bug reports, questions, comments, code, whatever you'dlike to give us. We also have a mailing list for softwareannouncements. Write us atclick@pdos.lcs.mit.edu- The Click maintainers:  Eddie Kohler  and others