diff options
author | peter <peter@FreeBSD.org> | 1995-12-30 19:02:48 +0000 |
---|---|---|
committer | peter <peter@FreeBSD.org> | 1995-12-30 19:02:48 +0000 |
commit | c3f352d4ad515968c54d216a0e53252eff8ab3ef (patch) | |
tree | 48ddeda3c6c8d8572cc34bf52ccf9cb9bd97d488 /sbin/ipfw | |
parent | ab124e78b0271ddb904b761b31e5c9a0cf24e070 (diff) | |
download | FreeBSD-src-c3f352d4ad515968c54d216a0e53252eff8ab3ef.zip FreeBSD-src-c3f352d4ad515968c54d216a0e53252eff8ab3ef.tar.gz |
This commit was generated by cvs2svn to compensate for changes in r13122,
which included commits to RCS files with non-trunk default branches.
Diffstat (limited to 'sbin/ipfw')
-rw-r--r-- | sbin/ipfw/README | 610 |
1 files changed, 0 insertions, 610 deletions
diff --git a/sbin/ipfw/README b/sbin/ipfw/README deleted file mode 100644 index 1cc296c..0000000 --- a/sbin/ipfw/README +++ /dev/null @@ -1,610 +0,0 @@ -***************************************************************************** -27 Oct 94 -Hi again! -So thanx to Brian McGovern , i'v took this piece of code in hands again -and made some changes: - 1) Port to FreeBSD 2.0 , so we will not go after time. - 2) Some minor changes in kernel part to improve speed and such.. - 3) Chane in behaviour: now any recently added firewall definition - preferred on other matching but older firewalls. - REMEMBER: in any case universal IP firewall has larger preference - then special TCP/UDP/ICMP firewalls. - 4) Cosmetical changes to control programm. Now it is called ipfw. - 5) Changed ip_firewall.* to ip_fw.* in kernel,and shortened some long - variable names. - 6) From now on we have user defined *policy*,which is DENY/ACCEPT for - every packet which does not matches any of firewalls.I.e.: if any - firewall defined and packet does not match them you may set it up - so it will be anyway throwed or anyway accepted. -Mostly that's all. -Bye! - --- - -= Ugen J.S.Antsilevich =- - NetVision - Commercial Internet Provider ------------------------------------------------------[C]--- -NetVision - Home of Israeli Commercial Internet - E-mail: ugen@NetVision.net.il - HTTP: http://www.NetVision.net.il/~ugen/ - Phone: +972-4-550330 Fax: +972-4-550122 - -***************************************************************************** -10 Jul 94 -Hi again...So i sitted and stared at this nice working tool and thought to -myself that it's nice but something there it needs and have not.. -So i took a piece of file and a keyboard and typed some strings. -What it was is: - -o List facility improved...Now listing of currently installed firewall - entries does not go through kernel printf's ,which is really unnice to - one who runs it NOT from console:) - -o Really important facility of deleting entries added..Yes , till this - day you had to remove all entries and then add them one by one again - to remove actually just one.Now it's over:) - -o All this changes documented in this readme,while you will see where i - added my words just by vast number of mistaces in English.Well,i hope - you will forgive one Russian guy like me:) - -So enjoy this new code and if you think it needs some additions - you -are welcome to suggest.Also i made some more warnings , while compiling -this code,i have no a clue where do they come from,however they does not -make any bad to programm.But if you will find way to remove them,feel free -to do it and post anywhere(and notify me as i also need this:) - - Bye! Ugen J.S.Antsilevich - - -########################################################################## -# Ugen J.S.Antsilevich NetVision (Israel) System Staff Member # -#------------------------------------------------------------------------# -# Email: ugen@NetVision.net.il | Phone: 972-4-550330 # -# ugen@NetManage.co.il | Fax: 972-4-550122 # -#------------------------------------------------------------------------# -# WWW HomePage: http://www.NetVision.net.il/~ugen # -# Special : Volk@Les.Tambov.SU # -########################################################################## - - -***************************************************************************** -8 Jul 94 -OK..so first of all,this is simple port to FreeBSD by Ugen J.S.Antsilevich -Actually all i had to do is to find appropriate place in kernel source files -for ipfirewall stuff..so all your thanks should go to the author... -Anyway i am porting it now to 1.1.5 (not much job though..:) so if you want -to ask something about write to me: - -ugen@NetVision.net.il - -That's it and let the --==REAL==-- author speak... -***************************************************************************** - -Here's my ipfirewall facility. I consider it to still be beta quality mostly -because the various interfaces are pretty crude. Here's some information that -you'll probably find useful (in roughly the order in which you'll need to know -it). Some of this will be absurdly simplistic. Better safe than sorry... - -This software was written for BSD/386. The current version has been ported -to BSD/386 v1.1. The context diffs are with respect to that version of -BSD/386. If you don't have access to BSD/386 v1.1 and can't make sense out of -the diffs, contact me and I'll send you the entire files (they are copyrighted -by UC-Berkeley with very 'friendly' conditions). - -Speaking of copyrights, here's mine: - -/* - * Copyright (c) 1993 Daniel Boulet - * Copyright (c) 1994 Ugen J.S.Antsilevich - * - * Redistribution and use in source forms, with and without modification, - * are permitted provided that this entire comment appears intact. - * - * Redistribution in binary form may occur without any restrictions. - * Obviously, it would be nice if you gave credit where credit is due - * but requiring it would be too onerous. - * - * This software is provided ``AS IS'' without any warranties of any kind. - */ - -Enough introductory stuff, here we go... - - 1) The file IPFIREWALL is the configuration of kernel i use with - IPFIREWALL and GATEWAY options enabled. You may not find it useful. - About the only key things are that it enables the IPFIREWALL - option and the GATEWAY option. IPFIREWALL turns on my - stuff and GATEWAY turns your machine into an IP router. - - There is nothing magical about the name of this file or the - ident name for the kernel. - - 2) The files ip_fw.c and ip_fw.h are new files that should be - placed into the /usr/src/sys/netinet directory. - - 3) The files ip_input.c and raw_ip.c are new patched versions of the - same files , they made up for version 2.0 of FreeBSD,however it was - some pre-Beta release we worked on , so to add it to other releases - just find all parts of code surrounded by: - #ifdef IPFIREWALL - .... - #endif - and place in the appropriate places in the same files. - All those files are in /usr/src/sys/netinet directory of corse. - - 4) Add the line "netinet/ip_fw.c optional ipfirewall" to the - file /usr/src/sys/conf/files. This tells the config program to - include the netinet/ip_fw.c file if the IPFIREWALL option is - defined for a kernel. - - 5) The Makefile and ipfw.c files should go into directory probably - back in your home directory tree somewhere. If this ever becomes a - part of the system then they should go into the (newly created) - directory /usr/src/sbin/ipfw. - - 6) Build yourself a kernel, make a backup of the current kernel and - and install the new one. It should behave in a completely normal - fashion since you won't have defined any firewalls yet. - - 7) Explore the ipfw program. The smartest way to do this is to - compile the program and then run it.To do it you SHOULD be root - as the programm uses setsockopt on RAW sockets to define firewalls, - and also reads kernel symbols.If any other user will run ipw - it will detect that it isn't being run by root and will just - complain and exit. - The ipfw program takes command line parameters - and (assuming they are valid) issues a single appropriate setsockopt - call. If you're defining 5 firewalls then you'll have to run the - program 5 times. See below for a description of the command syntax - of ipfirewall. - - ==================================================================== - WARNING!!! WARNING!!! WARNING!!! WARNING!!! WARNING!!! WARNING!!! - The ipfw program can be used to put your machine into very - disfunctional state.So if you want to test it make sure you - a) Have read carifully this README till it's end. - b) First time run it from machine console,as else you can - simply shut down your own access to it. - ==================================================================== - Make sure that you never setup the program as setuid root!!! Instead, - always run it from the root command line or from "/etc/rc.local" - as part of the boot process. - - 8) Use the "ipfirewall" checkb or checkf command (see below) to pass some - test packets through the firewalls that you've defined. - - 9) You may find it useful to create a file in which the first line is - "ipfirewall flush" to flush any existing firewalls and the remaining - lines are the ipfirewall commands needed to define the firewalls that - you want to use. This will ensure that you're always working from a - known state. - - 10) If you've gotten this far then you're probably ready to let the critter - see prime time. Copy your file of ipfirewall commands into the - /etc/rc.local file and reboot the system. Once you're up, use the - ipfirewall list command to see that you've got the firewalls that you - wanted and try to test the firewall with real packets from trusted - and untrusted hosts. - -Enough of that. Here's the syntax for the ipfirewall command. It is rather -complex and yet simple at the same time (if you know what I mean). There -are seven sub-commands. Probably the easiest way to get into this is to give -you a roughly BNF style grammar for the command (curly brackets are used for -precedence, alternatives are separated by |, optional things are enclosed -in square brackets, white space is required if it appears below and must -not appear if there isn't any between the tokens below (i.e. no white space -around periods, colons or slashes, whitespace required between all other -tokens)): - - command ::= ipfirewall <list> | <flush> | <check> | <add> | <del> - - <list> ::= list - - <flush> ::= flush - - <check> ::= { checkb[locking] | checkf[orwarding] } <chkparms> - - <add> ::= { addb[locking] | addf[orwarding] } <add-del-parms> - - <del> ::= { delb[locking] | delf[orwarding] } <add-del-parms> - - <chkparms> ::= <protocol> from <ipaddr> <port> to <ipaddr> <port> - - <protocol> ::= tcp | udp - - <ipaddr> ::= <int>.<int>.<int>.<int> | <hostname> - - <hostname> ::= a host name from /etc/hosts - - <port> ::= <int> | <service> - - <service> ::= a service from /etc/services - - <int> ::= a non-negative integer - - <add-del-parms> ::= { accept | deny } { <universal_firewall> | <protocol_firewall> } - - <universal_firewall> ::= all from <masked_ipaddr> to <masked_ipaddr> - - <masked_ipaddr> ::= { <ipaddr>/<bits> } | { <ipaddr>:<ipaddr> } | <ipaddr> - - <bits> ::= integer in the range 0 to 32 inclusive - - <protocol_firewall> ::= <protocol> from <end_firewall> to <end_firewall> - - <end_firewall> ::= <masked_ipaddr> <port_list> - - <port_list> ::= [ <port>:<port> ] <sub_port_list> - - <sub_port_list> ::= <port> [ <sub_port_list> ] - -Although I think that the above grammar is complete, it isn't exactly what -one would call easy to comprehend! Here's the basic idea along with what -each of the forms mean: - - The "ipfirewall list" command prints a list of the firewalls on both the - forwarding and blocking chain in some more or less understudable format. - - The "ipfirewall flush" command empties the two firewall chains. - - The "ipfirewall addblocking" and "ipfirewall addforwarding" commands take - a firewall description and add the firewall to the appropriate firewall - chain.Take notice,that if you will add some description more then once, - it will take more then one entry in memory.It does not lead to significant - slow down of computer operation though. - - The "ipfirewall delblocking" and "ipfirewall delforwarding" commands take - a firewall description and deletes the firewall from the appropriate - firewall chain.The description must be exactly the same as it was defined - by add command.One delete command removes ALL same entries from firewall - chains. - - There are two basic kinds of firewall descriptions. Universal firewall - descriptions match all IP packets between specified pairs of hosts. - Universal firewalls only check IP addresses (i.e. they match any combination - of protocol and port numbers). Protocol-specific firewalls match either - TCP/IP or UDP/IP packets between specified pairs of hosts. In addition - to host descriptions, protocol-specific firewalls optionally take a - description of which port numbers to match. - - A host description consists of an IP address and a mask. The IP address - is specified as either a domain name or in the familiar - nn.nn.nn.nn format. The mask indicates how much of the IP address - should be looked at when vetting packets. There are two ways to - specify the mask. The first way is to suffix the IP address in the - firewall with a slash and an integer in the range 0 through 32 inclusive. - This integer is taken to be the number of high order bits of the IP - address which are to be checked (for example, 192.153.211.0/24 checks - the top 24 bits of the IP address, 192.153.211.17/32 checks all the - bits and 0.0.0.0/0 checks none of the bits (i.e. all IP addresses are - matched by this example)). The second way to specify a mask is to - suffix the IP address with a colon followed by another IP address. - This second address is the mask. Specifications equivalent to the - above three examples using this syntax would be - - 192.153.211.0:255.255.255.0 - 192.153.211.17:255.255.255.255 - 0.0.0.0:0.0.0.0 - - The first form is taken from the syntax accepted by a Telebit NetBlazer. - The second form is more along the lines of how a netmask is specified - in /etc/netmasks. Finally, if no mask is specified then a mask of all - 1's is supplied (i.e. no mask is equivalent to /32 or :255.255.255.255). - - The optional description of port numbers to mask can take three forms. - The simplest form is to omit the list in which case all port numbers - match. The next form is to specify a list of port numbers (either as - positive integers or service names from /etc/services). The final form - is actually a special case of the second form in which the first pair - of port numbers is separated by a colon instead of white space. This - pair specifies a range of port numbers (i.e. x:y specifies that all - ports between x and y inclusive should match). A port description - matches a particular port number if any of the following is true: - - - the port description is null - - the first pair of port numbers is a range and the port number - is in the range (inclusive) - - the port number is equal to any of the port numbers in the list - - There is a limit of a total of 10 port numbers in the source and - destination port lists. This limit is arbitrary and easy to increase. - It is determined by the value of the IP_FIREWALL_MAX_PORTS #define - variable in ip_firewall.h. Each increase of 1 for this value adds two - bytes to the size of each firewall. Since the size of a firewall is only - slightly over 30 bytes right now, this limit of 10 could probably - be increased by quite a bit before it became a concern. I've been - thinking of increasing it to 20 which would be longer than any - reasonable firewall would need and would only consume 20 more bytes - per firewall. The counter argument to any increase is that it is - always possible to construct an equivalent set of two or more firewalls - that behaves like a single firewall with a really long port list. - - This probably all sounds hopelessly complicated. It is actually not - all that tricky (I'm just not very good at explaining it yet). A few - examples will probably help a lot now: - - Block all IP packets originating from the host hackers-den: - - ipfirewall addb deny all from hackers-den to 0.0.0.0/0 - - Block all telnet packets to our telnet server from anywhere: - - ipfirewall addb deny tcp from 0.0.0.0/0 to mymachine/32 telnet - - Don't forward telnet, rlogin and rsh packets onto our local - class C network: - - ipfirewall addf deny tcp from 0.0.0.0/0 to ournetwork/24 telnet login shell - - Don't let anyone on the local machine or any machine inside - our local network ftp access to games.com: - - ipfirewall addb deny tcp from games.com ftp to 0.0.0.0/0 - - This last one might look a little strange. It doesn't prevent - anyone from sending packets to the games.com ftp server. What it - does do is block any packets that the games.com ftp server sends - back! - - The "ipfirewall checkblocking" and "ipfirewall checkforwarding" commands - take a description of an IP packet and check to see if the blocking - or forwarding chain of firewalls respectively accept or reject the packet. - It is used to make sure that the firewalls that you've defined work as - expected. The basic syntax is probably best understood by looking at - a couple of examples: - - ipfirewall checkb from bsdi.com 3001 to mymachine telnet - - checks to see if the blocking firewall will block a telnet packet from - a telnet session originating on bsdi.com to the host mymachine will be - blocked or not. Note that someone connecting to our telnet server - could be using practically any port number. To be really sure, the - firewall used to prevent access should be as simple as possible and/or - you should try a variety of port numbers in addition to the rather - arbitrarily chosen port of 3001. - - One final note on the check* ,add* and del* command syntax. The noise word - "to" exists in the syntax so that I can detect the end of a list of - port numbers in the from description. Since I needed a noise word to - detect this case, I added the noise word "from" in front of the from - case for consistency. - - Finally, have a look at the file "filters". It is the set of filters - that I run at home.<Danny> - Also check "scripts",where individual access restrictions written. - We use those for our dial-in PPP/SLIP users,to allow some of them - to access our internal networks,while disallowing other.This way we - open access to user's IP,when he enters the system ,and shut it - down when he leaves.All those changes may be applyed at any time, - and so entries added and deleted from firewall while system is - is working.No any side effects will arise.<Ugen> - -Now for a bit of a description of how the firewalls are applied (i.e. what -happens in the kernel): - - When an IP packet is received, the ipintr() routine in ip_input.c is - called. This routine does a bit of basic error checking. If it - detects any errors in the packet it generally drops the packet on - the floor. The idea behind the ipfirewall facility is to treat packets - that we don't want to accept as bad packets (i.e. drop them on the - floor). The ipfirewall facility intercedes in the normal processing - at two points. Just after the basic sanity checks are done, we pass - any packets not targeted at the loopback network (127.0.0.0/8) to the - firewall checker along with the chain of blocking firewalls.If the firewall - checker tells us to block the packet then we branch to the "bad:" label - in ipintr() which is where all bad packets are dropped on the floor. - Otherwise, we allow normal processing of the packet to continue. The - exact point at which we intercede was chosen to be after the basic - sanity checking and before the option processing is done. We want to - be after the basic sanity checking so that we don't have to be able - to handle complete garbage. We want to be before the option processing - because option processing is done in separate rather complex routine. - Why bother doing this special processing if we might be dropping the - packet? - - The second point at which we intercede is when a packet is about to be - forwarded to another host. All such packets are passed to the ip_forward - routine. The ipfirewall code is at the very top of this routine. If - the packet isn't targetted at the loopback interface (is it possible - that it could be when we reach this point? I doubt it but safety first) - then pass the packet to the firewall checker along with the forwarding - firewall chain. If the firewall checker indicates that the packet should - not be forwarded then we drop in (using code copied from a few lines - further into the routine which drops broadcast packets which are not - to be forwarded). - -There are a couple of consequences of this approach: - - 1) Packets which are blocked are never forwarded (something to keep - in mind when designing firewalls). - 2) Packets targeted at the loopback interface (127.0.0.0/8) are never - blocked. Blocking packets to the loopback interface seems pointless - and potentially quite confusing. It also makes a possibly common - case very cheap. - 3) The sender of a packet which is blocked receives no indication that - the packet was dropped. The Telebit NetBlazer can be configured to - silently drop a blocked packet or to send back a "you can't get there - from here" packet to the sender. Implementing the later would have - been more work (possibly quite a bit more, I don't really know). Also, - I don't see any reason to give a potential hacker any more information - than necessary. Dropping the packet into the bit bucket seems like - the best way to keep a hacker guessing.<Danny> - Well,anyway i working on this feature.It would be made optional and - configurable by some ICMP_UNREACH_ON_DROP or like this.<Ugen> - -Now for some details on how the firewall checker works: - - The firewall checker takes two parameters. The first parameter is a pointer - to the packet in question. The second parameter is a pointer to the - appropriate firewall chain. At the present time, the firewall checker passes - these parameters to a second routine which is the real firewall checker. - If the real checker says NO then an appropriate message is printed - onto the console. This is useful for debugging purposes. Whether or - not it remains in the long term depends on whether it is considered useful - for logging purposes (I'm a little reluctant to leave it in since it - provides a hacker with a way to commit a "denial of service" offense - against you by filling up your /var/log/messages file's file system - with error messages. There are ways of preventing this but ...<Danny>). - In default configuration now no information about dropped packets - printed.You may,however,define it,as i do by adding - option IPFIREWALL_VERBOSE - to your kernel configuration file.Very useful thingy!<Ugen> - - A return value of 0 from this routine (or the real firewall checker) - indicates that the packet is to be dropped. A value of 1 indicates - that the packet is to be accepted. In the early testing stages you - might want to make the top level firewall checker always return 1 even - if the real checker returns 0 just in case the real firewall checker - screws up (or your firewalls aren't as well designed as they should be). - In fact, this might be a useful optional feature (providing a way to - leave a door unlocked doesn't seem all that wise but it has to be - balanced against the inconvenience to legitimate users who might get - screwed up by poorly designed firewalls). - - The real firewall returns 1 (accept the packet) if the chain is empty. If - efficiency is a concern (which it is in this code), this check should - be done in ip_input.c before calling the firewall checker. - - Assuming that there is a firewall chain to scan through, the real firewall - checker picks up the src and dst IP addresses from the IP packet. It - then goes through the firewall chain looking for the first firewall that - matches the packet. Once a matching firewall has been found, a value of - 1 is returned if the firewall is an accept firewall and a value of 0 is - returned otherwise. - - The following processing is done for each firewall on the chain: - - 1) check the src and dst IP addresses. If they don't match then - there isn't any point in looking any further at this firewall. - This check is done by anding the packet's IP addresses the - with appropriate masks and comparing the results to the - appropriate addresses in the firewall. Note that the mask is - NOT applied to the address in the firewall. If it has any 1 - bits that are 0 bits in the mask then the firewall will never - match (this will be checked in ipfirewall soon). If the addresses - match then we continue with the next step. - - 2) If the firewall is a universal firewall then we've got a match. - Return either 0 or 1 as appropriate. Otherwise, continue with - the next step. - - 3) Examine the IP protocol from the packet. If we havn't had to - look at it before then we get it and set a local variable to - IP_FIREWALL_TCP for TCP/IP packets, IP_FIREWALL_UDP for UDP/IP - packets, IP_FIREWALL_ICMP for ICMP packets, and IP_FIREWALL_UNIVERSAL - for all other packet types. Also, if the packet is a TCP/IP or - a UDP/IP packet, save the source and destination port numbers - at this point (taking advantage of the fact that the port numbers - are stored in the same place in either a TCP/IP or a UDP/IP - packet header). If the packet is neither a TCP/IP or a UDP/IP - packet then this firewall won't match it (on to the next firewall). - If this packet's protocol doesn't match this firewall's protocol - (which can't be universal or we wouldn't be here) then on to - the next firewall. Otherwise, continue with the next step. - - 4) We're checking either a TCP/IP or a UDP/IP packet. If the - firewall's source port list is empty or the packet's source - port matches something in the source port list AND if the firewall's - destination port list is empty or the packet's destination - port matches something in the destination port list then - we've got a match (return 0 or 1 as appropriate). Otherwise, - on to the next firewall. - - As indicated above, if no packet on the chain matches the packet then - it is accepted if the first firewall was a deny firewall and it is rejected - if the first firewall was an accept packet. This is equivalent to the - default behaviour of a Telebit NetBlazer. They provide a way to override - this behaviour. I'm not convinced that it is necessary (I'm open to - suggestions). - -That's about it for the firewall checker. The ipfirewall program communicates -with the kernel part of the firewall facility by making setsockopt calls -on RAW IP sockets. Only root is allowed to open a RAW IP socket. This -ensures that only root uses ipfirewall to manipulate the firewall facility. -Also, somewhere in the kernel source or on a man page, I read that the -RAW IP setsockopt calls are intended for manipulating the IP protocol layer -as opposed to manipulating any particular instance of a socket. This seems -like a reasonable description of what the firewall setsockopt command -codes do. - -There are seven setsockopt command codes defined by the firewall facility -(in netinet/in.h). They are: - - IP_FLUSH_FIREWALLS flush (i.e. free) both firewall chains. - - IP_ADD_FORWARDING_FIREWALL add firewall pointed at by optval parm to - the end of the forwarding firewall chain. - - IP_ADD_BLOCKING_FIREWALL add firewall pointed at by optval parm to - the end of the blocking firewall chain. - - IP_DEL_FORWARDING_FIREWALL delete firewall pointed at by optval parm - from the forwarding firewall chain. - - IP_DEL_BLOCKING_FIREWALL delete firewall pointed at by optval parm - from the blocking firewall chain. - - IP_CHECK_FORWARDING_FIREWALL pass the IP packet do the firewall checker - along with the forwarding firewall chain. - Return 0 if packet was accepted, -1 (with - errno set to EACCES) if it wasn't. - - IP_CHECK_BLOCKING_FIREWALL pass the IP packet do the firewall checker - along with the blocking firewall chain. - Return 0 if packet was accepted, -1 (with - errno set to EACCES) if it wasn't. - - The IP_ADD_* and IP_DEL_* command codes do a fair bit of validity checking. - It is quite unlikely that a garbage firewall could get past them that - would cause major problems in the firewall checker. It IS possible for - a garbage packet to get past the checks which causes major grief because - it either blocks or accepts packets according to unusual rules (the rules - will conform to the ones described above but will probably come as quite - a surprise). - - The IP_CHECK_* command codes expect the optval parameter to point - to a struct ip immediately followed by a header appropriate to the protocol - value described in the ip_p field of the ip header. The exact requirements - are as follows: - - - The length of the optval parameter must be at least - - sizeof(struct ip) + 2 * sizeof(u_short) - - since this is the amount of memory that might be referenced by - the firewall checker. - - - The ip_hl field of the ip structure must be equal to - - sizeof(struct ip) / sizeof(int) - - since this value indicates that the tcp/udp/??? header immediately - follows the ip header (appropriate for the purposes that this - interface is intended for). - - Failure to follow these rules (for either the IP_ADD_*,IP_DEL_* or the - IP_CHECK_*_FIREWALL commands) will result in a return value of -1 with - errno set to EINVAL (for now, it will also result in an appropriate - message on the console). - - To read current configuration of firewalls,the kvm_read() function used. - Symbols,which you have to find are : - struct ip_firewall * ip_firewall_blocking_chain ; - struct ip_firewall * ip_firewall_forwarding_chain ; - Both are pointers to the linked list of firewall entries. - Of corse you have to be at least kmem group member,to read kernel symbols. - -That's about all that I can think of for now. There are a couple of details -that are worth reading about in the ip_firewall.h file. Other than that, let -me know how you do. If you have any problems, give me a call at home (403 -449-1835) or send me e-mail at "danny@BouletFermat.ab.ca". If you call, please -keep in mind that I live in the Canadian Mountain timezone (GMT-0600). - --Danny - -So that's it..if you want to say something to me-call me or mail: -Phone: 972-4-550-330 -E-mail ugen@NetVision.net.il -If you call,remember that i live in Israel timezone which is GMT+02. - --Ugen - |