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This tab
allows you to set rules for capturing packets. If one or more rules
are set, the program filters packets based on these rules and
displays only the packets that comply with the rules. Note that
CommView is not a firewall, and when you set rules, packets are
still processed by the operating system; they are not just
displayed and logged by CommView. If a rule is set, the name of the
corresponding tab is displayed in bold font.
You can save
your rules configuration(s) to a file and load them by using
the Rules
command of the
program's menu.
Since LAN
traffic can often generate a high number of packets, it is
recommended that you use rules to filter out unnecessary packets.
This can considerably reduce the amount of system resources
consumed by the program. If you want to enable/disable a rule,
select the appropriate branch on the left side of the window
(e.g. IP
Addresses or Ports),
and check or uncheck the box describing the rule
(Enable
IP Address rules or Enable
port rules). There are eight types
of rules that can be used:
Protocols & Direction
Allows you
to ignore or capture packets based on Ethernet (Layer 2) and IP
(Layer 3) protocols, as well as on packet direction.
This
example shows how to make the program capture only inbound and
outbound ICMP and UDP packets. All other packets in the IP family
will be ignored; all pass-through packets will be ignored
also.
MAC Addresses
Allows you
to ignore or capture packets based on MAC (hardware) addresses.
Enter a MAC address in the
Add Record frame,
select the direction (From,
To, or
Both), and
click
Add MAC Address. The new
rule will be displayed. Now you can select the action to be taken
when a new packet is processed: the packet can be either captured
or ignored. You can also click on the MAC Aliases button to get the
list of aliases; double-click on the alias you would like to add,
and the corresponding MAC address will appear in the input
box.
This
example shows how to make the program ignore packets that come from
0A:DE:34:0F:23:3E. All packets that come from other MAC addresses
will be captured.
IP Addresses
Allows you to
ignore or capture packets based on IP addresses. Enter an IP or
IPv6 address in the Add
Record frame, select the
direction (From,
To,
or
Both),
and click Add IP
Address. You can use wildcards to
specify blocks of IP addresses. The new rule will be displayed. Now
you can select the action to be taken when a new packet is
processed: the packet can be either captured or ignored. You can
also click on the IP Aliases button to access the list of aliases;
double-click on the alias you would like to add, and the
corresponding IP address will appear in the input box.
This
example shows how to make the program capture the packets that go
to 63.34.55.66, go to and come from 207.25.16.11 and come from all
addresses between 194.154.0.0 and 194.154.255.255. All packets that
come from other addresses or go to other addresses will be ignored.
Since IP addresses are used in the IP protocol, such configuration
will automatically make the program ignore all non-IP
packets. Usage of IPv6 addresses
requires Windows XP or higher and that the IPv6 stack be
installed.
Ports
Allows you
to ignore or capture packets based on ports. Enter a port number in
the
Add Record frame,
select the direction (From,
To, or
Both), and
click
Add Port. The new
rule will be displayed. Now you can select the action to be taken
when a new packet is processed: the packet can be either captured
or ignored. You can also click on the
Port Reference button to
get a list of all known ports; double-click on the port you would
like to add and its number will appear in the input box. Ports can
also be entered as text; for example, you can type in
http or
pop3, and the
program will convert the port name to the numeric value.
This
example shows how to make the program ignore packets that come from
port 80 and go to and come from port 137. This rule will prevent
CommView from displaying inbound HTTP traffic, as well as inbound
and outbound NetBIOS Name Service traffic. All packets coming to
and from other ports will be captured.
TCP Flags
Allows you
to ignore or capture packets based on TCP flags. Check a flag or a
combination of flags in the
Add Record frame, and
click
Add Flags. The new
rule will be displayed. Now you can select the action to be taken
when a new packet with the entered TCP flags is
processed: the
packet can be either captured or ignored.
This
example shows how to make the program ignore TCP packets with the
PSH ACK flag. All packets with other TCP flags will be
captured.
Text
Allows you to
capture packets that contain certain text. Enter a text string in
the Add
Record frame and click
Add
Text.
The new rule will be displayed. Now you can select the action to be
taken when a new packet is processed: the packet can be either
captured or ignored.
This example
shows how to make the program capture only the packets that contain
"GET". Check the Case
sensitive box if you want the rules
to be case sensitive. Check the UTF8
or
UTF16
box if you
want the rule to match the text encoded using the respective
encodings. All other packets that do not contain the text mentioned
above will be ignored. If you would like to create a rule based on
hex byte sequences, when the text is not printable (e.g. 0x010203),
use the
Advanced
Rules.
Process
Allows you to
capture packets based on the process name. Enter a process name in
the Add
Record frame and click
Add
Process Name. The new rule will be
displayed. Now you can select the action to be taken when a new
packet is processed: the packet can be either captured or ignored.
You can enter partial process names, e.g. netscp
or
net;
any process name that contains such a substring will match the
rule. Process names are not case-sensitive.
This example
shows how to make the program capture only the packets that were
sent or received by netscp.exe.
Packets sent by other processes will be ignored.
Advanced
Advanced
rules are the most powerful and flexible rules that allow you to
create complex filters using Boolean logic. For the detailed help
on using advanced rules, please refer to the Advanced
Rules chapter.
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