Optional Features=================   Some packages pay attention to `--enable-FEATURE' options to`configure', where FEATURE indicates an optional part of the package.They may also pay attention to `--with-PACKAGE' options, where PACKAGEis something like `gnu-as' or `x' (for the X Window System).  The`README' should mention any `--enable-' and `--with-' options that thepackage recognizes.   For packages that use the X Window System, `configure' can usuallyfind the X include and library files automatically, but if it doesn't,you can use the `configure' options `--x-includes=DIR' and`--x-libraries=DIR' to specify their locations.   The following configuration switches are available for Snort:`--enable-flexresp'     Enable the 'Flexible Response' code, that allows you to     cancel hostile connections on IP-level when a rule matches.     When you enable this feature, you also need the 'libnet'-library     that can be found at http://www.packetfactory.net/libnet.     See README.FLEXRESP for details.     This function is still ALPHA, so use with caution.Specifying the System Type==========================   There may be some features `configure' can not figure outautomatically, but needs to determine by the type of host the packagewill run on.  Usually `configure' can figure that out, but if it printsa message saying it can not guess the host type, give it the`--host=TYPE' option.  TYPE can either be a short name for the systemtype, such as `sun4', or a canonical name with three fields:     CPU-COMPANY-SYSTEMSee the file `config.sub' for the possible values of each field.  If`config.sub' isn't included in this package, then this package doesn'tneed to know the host type.   If you are building compiler tools for cross-compiling, you can alsouse the `--target=TYPE' option to select the type of system they willproduce code for and the `--build=TYPE' option to select the type ofsystem on which you are compiling the package.Sharing Defaults================   If you want to set default values for `configure' scripts to share,you can create a site shell script called `config.site' that givesdefault values for variables like `CC', `cache_file', and `prefix'.`configure' looks for `PREFIX/share/config.site' if it exists, then`PREFIX/etc/config.site' if it exists.  Or, you can set the`CONFIG_SITE' environment variable to the location of the site script.A warning: not all `configure' scripts look for a site script.Operation Controls==================   `configure' recognizes the following options to control how itoperates.`--cache-file=FILE'     Use and save the results of the tests in FILE instead of     `./config.cache'.  Set FILE to `/dev/null' to disable caching, for     debugging `configure'.`--help'     Print a summary of the options to `configure', and exit.`--quiet'`--silent'`-q'     Do not print messages saying which checks are being made.  To     suppress all normal output, redirect it to `/dev/null' (any error     messages will still be shown).`--srcdir=DIR'     Look for the package's source code in directory DIR.  Usually     `configure' can determine that directory automatically.`--version'     Print the version of Autoconf used to generate the `configure'     script, and exit.`configure' also accepts some other, not widely useful, options.Platform Specific Notes=======================* 64bit platforms:------------------On some 64bit Linux systems (e.g. with Fedora distributions), whenconfiguring snort with MySQL output support, the necessary library maynot be found automatically by the configure script, giving thefollowing error when 'configure' is run:**********************************************  ERROR: unable to find mysqlclient library (libmysqlclient.*)  checked in the following places        /usr        /usr/lib        /usr/mysql        /usr/mysql/lib        /usr/local        /usr/local/lib        /usr/local/mysql        /usr/local/mysql/lib**********************************************In this case, libmysqlclient.* may actually be found in /usr/lib64/mysql,and the path will need to be explicitly specified in this manner:configure --with-mysql-libraries=/usr/lib64/mysqlNote, you may also specify alternate locations for the mysql headerfiles using --with-mysql-includes.  Specifying a directory as partof the --with-mysql option to configure will be deprecated in thefuture.* Linux:--------  With kernels 2.2.x and higher you may get `snort [pid] uses obsolete  (PF_INET, SOCK_PACKET)' warnings. This is because you use some older  implementation of libpcap library and you need an upgrade. The recent  version of libpcap could be found at www.tcpdump.org page.  On linux  with kernels 2.2.x and higher you may also get feature to monitor  several interfaces down to network level (session + TCP + IP) if you  link your snort with the lattest version of libpcap which incorporates  Sebastian Krahmer's patch for interface 'any'.  (Consult http://www.tcpdump.org for details).* IRIX------[ noticed by Scott A. McIntyre <scott@whoi.edu>] There's problem with GCC on IRIX platform which causes certain missbehaviourof snort.>From the SGI web site:Gcc does not correctly pass/return structures which are smaller than 16bytes and which are         not 8 bytes. The problem is very involved and difficult to fix.It affects a number of other targets also, but irix6 is affected         the most, because it is a 64 bit target, and 4 byte structuresare common. The exact problem is that structures are being         padded at the wrong end, e.g. a 4 byte structure is loaded intothe lower 4 bytes of the register when it should be loaded         into the upper 4 bytes of the register.          Gcc is consistent with itself, but not consistent with the SGIC compiler [and the SGI supplied runtime libraries], so the         only failures that can happen are when there are libraryfunctions that take/return such structures. There are very few         such library functions. I can only recall seeing a few of them:inet_ntoa, inet_aton, inet_lnaof,         inet_netof, and semctl.          A possible workaround: if you have a program that callsinet_ntoa and friends or semctl, and your kernel supports         64-bit binaries (i.e. uname -a prints IRIX64 rather than justIRIX), then you may compile with gcc -mabi=64 to         workaround this problem. More information is available at:http://freeware.sgi.com/2000Feb/Installable/gcc-2.8.1-sgipl2.html* SunOS------- Similar problem with GCC has been noticed on SunOS4.x platforms which causessnort to SIGBUS at certain places. Please use naitive C compiler instead.* MAC OSX---------On Darwin (maybe others), the configure script shipped as part of thesource distribution needs to be recreated.  To do this, run thefollowing commands:aclocal -I m4autoheaderautomake --add-missing --copyautoconfIf you plan to use the dynamic plugin capability (ie,configure --enable-dynamicplugin), snort needs to be linked usingthe two level namespace.  To do this, set the LD_TWOLEVEL_NAMESPACEenvironment variable to something prior to running configure.An example:$ export LD_TWOLEVEL_NAMESPACE=1$ configure --enable-dynamicplugin* Open BSD/Free BSD/MAC OSX---------------------------On certain BSD-based platforms, the make install may not symlink theversion specific shared libraries to the non-versioned shared library.This could cause a failure to load when using dynamic libraries.Work arounds:1) Create the symlink's by hand after make install.  The shared librariescan be located under /usr/local/lib/snort_dynamicengine and/usr/local/lib/snort_dynamicpreprocessor.  1a) For OpenBSD, the object files ending in .0 will need to besymlinked to .so. For example:ln -s libsf_smtp_preproc.0  libsf_smtp_preproc.so1b) For MAC OSX, the object files ending in .0 will need to besymlinked to .dylib. For example:ln -s libsf_smtp_preproc.0  libsf_smtp_preproc.dylib2) Use the --dynamic-preprocessor-lib (rather than--dynamic-preprocessor-lib-dir) to load the version specificshared library.3) Use the config directive dynamicpreprocessor file (rather thandynamicpreprocessor directory) to load the version specificshared library.* FreeBSD 6.x-------------If you run the auto tools (instead of using the deliveredconfigure script), you may need to include -I /usr/local/share/aclocal(in addition to -I m4) as arguments to aclocal.  This is requiredto set up the correct info for using LIBTOOL with aclocalversion 1.9 that ships with FreeBSD.In this case, the following recommended commands should be usedto configure snort prior to using make:libtoolize --automake --copyaclocal -I m4 -I /usr/local/share/aclocalautoheaderautomake --add-missing --copyautoconfThen run configure with any desired options (--enable-dynamicplugin,--enable-inline, etc).