Copyright (c) 2005 Gleb Smirnoff All rights reserved. Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met: 1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer. 2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or othe...
NAMEng_ipfw - interface between netgraph and IP firewall
SYNOPSISIn netinet/ip_var.h In netgraph/ng_ipfw.h
DESCRIPTIONThe ipfw node implements interface between ipfw(4) and netgraph(4) subsystems.
HOOKSThe ipfw node supports an arbitrary number of hooks, which must be named using only numeric characters.
OPERATIONOnce the sysctl Cm net.inet.tcp.syncookies module is loaded into the kernel, a single node named ipfw is automatically created. No more ipfw nodes can be created. Once destroyed, the only way to recreate the node is to reload the sysctl Cm net.inet.tcp.syncookies module.
Packets can be injected into netgraph(4) using either the netgraph or ngtee commands of the ipfw(8) utility. These commands require a numeric cookie to be supplied as an argument. Packets are sent out of the hook whose name equals the cookie value. If no hook matches, packets are discarded. Packets injected via the netgraph command are tagged with Vt struct ipfw_rule_ref . This tag contains information that helps the packet to re-enter ipfw(4) processing, should the packet come back from netgraph(4) to ipfw(4).
Packets received by a node from netgraph(4) subsystem must be tagged with Vt struct ipfw_rule_ref tag. Packets re-enter IP firewall processing at the next rule. If no tag is supplied, packets are discarded.