Cabletron Systems CyberSWITCH CSX150 User Manual

Also see for CyberSWITCH CSX150: User guide Quick start guide

Contents

USER’S GUIDE232 CyberSWITCH6. Select IP Information.7. Select either IP Input Filter or IP Output filter.8. Provide the filter name.IP F ILTERS CONFIGURATION ELEMENTSThe following elements are described in terms of the individual comparisons which make up thepacket types. When an IP packet is subjected to a filter, the following comparisons are executed.The final result of the comparisons is a “match” if all comparisons are true, and a “no match”otherwise.IP ADDRESSESThese elements allow filtering based on the IP Addresses, which are expressed in two dotteddecimal quantities, a Mask and a Target. The comparison entails the logical “AND” operation ofthe packet’s IP Address and the specified Mask. The result of this operation is compared againstthe Target in either an EQUAL (EQ) or NOT EQUAL (NEQ) operation for determining if a matchhas occurred. The mask is used to create wild card or don’t care conditions for the addresscomparison (‘1’ bits are significant and ‘0’ bits are don’t cares).Examples:IP PROTOCOLThis element applies a check to the Protocol field of the IP header using either an EQUAL or NOTEQUAL comparison. Symbolic mnemonics are supplied for the most popular upper level protocols(TCP, UDP, ICMP); when using an EQUAL comparison on these values, the correspondingprotocol-specific comparisons are then enabled. A numeric value N (an unsigned quantity between0 and 255) can be used for any other protocol without a specific mnemonic. “ANY” can also bespecified as the protocol and is the default value, along with an EQUAL comparison, to yield thewild card value.TCP AND UDP PORTSThese elements allow filtering based on the TCP Source and Destination Port fields, which aretreated as 16 bit unsigned quantities (0-65535). These can be used to trap applications that havewell-known port addresses, such as Telnet, FTP, etc. The packet’s port value is compared to thevalue in the type using the specified operator:0.0.0.0 EQ 0.0.0.0 Matches any IP address (wildcard and de-fault).255.255.255.0 EQ 128.131.23.0 If Class B network 128.131.0.0 is subnettedwith 8 bits, this comparison matches anyhost on subnet 23.255.255.255.0 NEQ 128.131.23.0 If Class B network 128.131.0.0 is subnettedwith 8 bits, this comparison matches anyhost except those on subnet 23255.255.255.255 EQ 128.131.23.59 Matches exactly the host 128.131.23.59255.255.255.255 NEQ 128.131.23.59 Matches every host except 128.131.23.59