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diff --git a/contrib/ipfilter/README b/contrib/ipfilter/README deleted file mode 100644 index 8464af4..0000000 --- a/contrib/ipfilter/README +++ /dev/null @@ -1,101 +0,0 @@ -IP Filter - What's this about ? -============================ -Web site: http://coombs.anu.edu.au/~avalon/ip-filter.html -How-to: http://www.obfuscation.org/ipf/ipf-howto.txt - - The idea behind this package is allow those who use Unix workstations as -routers (a common occurance in Universities it appears) to apply packet -filtering to packets going in and out of them. This package has been -tested on all versions of SunOS 4.1 and Solaris 2.4/2.5, running on Sparcs. -It is also quite possible for this small kernel extension to be installed -and used effectively on Sun workstations which don't route IP, just for -added security. It can also be integrated with the multicast patches. -It has also been tested successfully on all of the modern free BSDs as -well as BSDI, and SGI's IRIX 6.2. - - The filter keeps a rule list for both inbound and outbound sides of -the IP packet queue and a check is made as early as possible, aiming to -stop the packet before it even gets as far as being checked for source -route options. In the file "BNF", a set of rules for constructing filter -rules understood by this package is given. The files in the directory -"rules", "example.1" ... "example.sr" show example rules you might apply. - - In practise, I've successfully isolated a workstation from all -machines except the NFS file servers on its local subnets (yeah, ok, so -this doesn't really increase security, because of NFS, but you get the -drift on how it can be applied and used). I've also successfully -setup and maintained my own firewalls using it with TIS's Firewall Toolkit, -including using it on an mbone router. - - When using it with multicast IP, the calls to fr_check() should be -before the packet is unwrapped and after it is encapsulated. So the -filter routines will see the packet as a UDP packet, protocol XYZ. -Whether this is better or worse than having it filter on class D addresses -is debateable, but the idea behind this package is to be able to -discriminate between packets as they are on the 'wire', before they -get routed anywhere, etc. - - It is worth noting, that it is possible, using a small MTU and -generating tiny fragmented IP packets to generate a TCP packet which -doesn't contain enough information to filter on the "flags". Filtering -on these types of packets is possible, but under the more general case -of the packets being "short". ICMP and UDP packets which are too small -(they don't contain a complete header) are dropped and logged, no questions -asked. When filtering on fragmented packets, the last fragment will get -through for TCP/UDP/ICMP packets. - -Bugs/Problems -------------- -If you have a problem with IP Filter on your operating system, please email -a copy of the file "BugReport" with the details of your setup as required -and email to darrenr@pobox.com. - -Some general notes. -------------------- - To add/delete a rule from memory, access to the device in /dev is needed, -allowing non-root maintenaince. The filter list in kernel memory is built -from the kernel's heap. Each packet coming *in* or *out* is checked against -the appropriate list, rejects dropped, others passed through. Thus this will -work on an individual host, not just gateways. Presently there is only one -list for all interfaces, the changes required to make it a per-interface list -require more .o replacements for the kernel. When checking a packet, the -packet is compared to the entire list from top to bottom, the last matching -line being effective. - - -What does what ? ----------------- -if_fil.o (Loadable kernel module) - - additional kernel routines to check an access list as to whether - or not to drop or pass a packet. It currently defaults to pass - on all packets. - -ipfstat - - digs through your kernel (need to check #define VMUNIX in fils.c) - and /dev/kmem for the access filter list and mini stats table. - Obviously needs to be run priviledged if required. - -ipf - - reads the files passed as parameters as input files containing new - filter rules to add/delete to the kernel list. The lines are - inserted in order; the first line is inserted first, and ends up - first on the list. Subsequent invocations append to the list - unless specified otherwise. - -ipftest - - test the ruleset given by filename. Reads in the ruleset and then - waits for stdin. - - See the man pages (ipf.1, ipftest.1, ipfstat.8) for more detailed - information on what the above do. - -mkfilters - - suggests a set of filter rules to employ and suggests how to add - routes to back these up. - -BNF - - BNF rule set for the filter rules - -Darren Reed -darrenr@pobox.com -http://coombs.anu.edu.au/~avalon/ip-filter.html |
