27-12
C
HAPTER
27: P
ACKET
F
ILTERS
The following filter file example would prevent forwarding of IP packets with
destination addresses that match the first 24 bits of the given IP address (that is,
addresses beginning with 188.039.150):
#filter
IP:
010 REJECT dst-addr = 188.039.150.000/24;
The following filter file rule example would allow forwarding of IP packets with
source address 192.077.100.032
and
destination address 201.128.011.034:
#filter
IP:
010 AND src-addr = 192.077.100.032;
020 ACCEPT dst-addr = 201.128.011.034;
Masks
These fields specify the number of bits to be used in the
source address
and
destination
address comparisons. Valid values are:
The masks are separated from source address and destination address by forward
slashes (/).
TCP and UDP Parameter
Filtering
TCP and UDP packets are typically sent from and destined for standard port
numbers that provide common network services, such as Domain Name Service
(DNS), Simple Network Management Protocol (SNMP), and TELNET. You can filter
TCP and UDP packets by source and destination ports by defining filter rules that
compare the port number in a TCP or UDP packet of a specific value.
The following filter file rule example would accept only TCP packets that have a
source port number of 24 or greater:
#filter
IP:
010 ACCEPT tcp-src-port >= 24;
020 DENY;
The following filter file rule example would accept only TCP packets with a
destination port in the range of 24-39:
#filter
IP:
010 AND tcp-dst-port>23;
020 ACCEPT tcp-dst-port<40;
030 DENY;
0
Match all packets with any IP address. The contents of source address
or destination address fields are unimportant.
8
Compare the first byte (octet) in the IP address.
16
Compare only the first two bytes of the IP addresses.
24
Compare only the first three bytes of the IP addresses.
32
Match the entire IP address. (Default)
Summary of Contents for OfficeConnect 3C100XF
Page 1: ...http www 3com com OfficeConnect Gateway CLI User s Guide Release 1 0 Part No 10042302 Rev AA ...
Page 14: ...xiv ...
Page 18: ...iv ABOUT THIS GUIDE ...
Page 30: ...1 12 CHAPTER 1 USING THE COMMAND LINE INTERFACE CLI ...
Page 50: ...3 14 CHAPTER 3 ADMINISTRATIVE CLI COMMANDS ...
Page 58: ...4 8 CHAPTER 4 CONFIGURING AND MANAGING USERS ...
Page 70: ...6 8 CHAPTER 6 BRIDGING COMMANDS ...
Page 78: ...8 4 CHAPTER 8 INTERFACE COMMANDS ...
Page 82: ...9 4 CHAPTER 9 ARP COMMANDS ...
Page 88: ...11 4 CHAPTER 11 DHCP COMMANDS ...
Page 124: ...12 36 CHAPTER 12 IP ROUTING COMMANDS ...
Page 134: ...13 10 CHAPTER 13 DNS COMMANDS ...
Page 142: ...15 6 CHAPTER 15 MULTICASTING AND IGMP COMMANDS ...
Page 160: ...17 8 CHAPTER 17 PPP COMMANDS ...
Page 182: ...21 6 CHAPTER 21 ADDRESS TRANSLATION COMMANDS ...
Page 186: ...22 4 CHAPTER 22 IPSEC COMMANDS ...
Page 188: ...23 2 CHAPTER 23 SECURITY ASSOCIATION SA COMMANDS ...
Page 192: ...24 4 CHAPTER 24 TCP COMMANDS ...
Page 204: ...25 12 CHAPTER 25 SNMP COMMANDS ...
Page 210: ...26 6 CHAPTER 26 IP FILTERS COMMANDS ...
Page 238: ...29 6 CHAPTER 29 TRACEROUTE COMMANDS ...
Page 255: ...xv RFC 1483 16 3 RFC 1483 MER 16 4 ...
Page 256: ...xvi ...
Page 260: ......