3Com OfficeConnect 3C100XF Cli User's Manual

Also see for OfficeConnect 3C100XF: Quick start guide

Contents

3Com OfficeConnect 3C100XF Cli User's Manual Manual pdf 212 page image

27-2 CHAPTER 27: PACKET FILTERS Data Filters - based on protocol-specific packet information Advertisement filters - based on broadcast packet information Generic filters - based on packet structureData Filters Data filters control network access based on the protocol, source / destinationaddress and port designation (for example, TCP and UDP port designations) of thepacket.The OfficeConnect Gateway supports IP-related filters only. This filter controlsnetwork access based on the protocol and source / destination address. IP filterrules allow filtering on source address, destination address, protocol type, sourceport, and port designation of the IP packet.Advertisement Filters Advertisement filters operate on network protocol packets that contain varyinginformation such as RIP. Filtering of these packets is performed by the specificprotocol process.IP-RIP is the advertising filter supported by the OfficeConnect Gateway. The filtercontrols the content of Routing Information Protocol (RIP) packets that are sentout or received on specific ports. The IP-RIP filtering process filters addresses fromthe RIP packet upon transmission (output) filter, and does not enter routes into theRouting Table upon receipt (input filter).Generic Filters Generic filters are specified by byte and offset values in a packet. Packets arefiltered by comparing the packet’s offset value and byte information with thevalues that you define in the filter. The Hub accepts or rejects the packet based onthe result.Creating generic filters can be a complex task. Only experienced users should usegeneric filters, and strictly in cases where data and advertising filters cannotprovide the filtering capabilities needed.Creating Filters The OfficeConnect Gateway performs packet filtering based on packet filteringrules that you create. This section describes how to create the packet filters andincludes the following topics: Filter File Components Creating Filter FilesFilter File Components You define the filtering rules used within filter files. Filter files are text files that arestored in FLASH memory. You can create and modify filter files using an off-linetext editor. You create the file using the syntax and format described here. Then,you save the file using a .flt extension, and use TFTP to transfer the file to theOfficeConnect GatewayTo be valid, a filter file must always have the following file descriptor on the firstline:#filterBe sure not to leave any blank space before the file descriptor. If you do, you’llcause an error to occur.