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This tool allows you to edit and send packets via your wireless
network adapter. To open the Packet Generator, click
Tools => Packet Generator,
or select a packet from the
Packets
tab, right-click on it, and select the
Send Packet
command.
Please read the following important information about the
limitations and peculiarities of using in the Packet Generator with
wireless adapters:
·Do
not use the Packet Generator unless you know exactly what effect
you want to achieve. Sending packets may produce unpredictable
results, and we strongly recommend refraining from using this tool
unless you are an experienced network administrator.
·Your
adapter firmware may fail to send certain packets, or it may send
certain packets multiple times. This behavior is fully controlled
by the firmware and is beyond our control.
·Your
adapter firmware may disallow you to send packets at an arbitrary
rate. It is quite possible that when you select the rate of 1000
packets per second, the firmware will actually send the packets at
a much slower rate.
Please note that the Packet Generator cannot and should not be used
for sending application-layer TCP streams, i.e. it cannot take care
of incrementing SEQ or ACK values automatically, adjusting
checksums and packet sizes and so forth. If you need to send a TCP
stream, you should use a Winsock-based application specifically
designed for that purpose. The Packet Generator is a tool for
replaying pre-captured data, testing firewalls and intrusion
detection systems, as well as for performing other specific tasks
that require manual packet crafting.
The Packet Generator allows you to change the packet contents and
have the packet decode displayed in the left window as you edit it.
You can create packets of any kind; you have full control over the
packet contents. For IP, TCP, UDP, and ICMP packets, you can
automatically correct the checksum(s) by clicking on the
Sigma
button. To assist you with packet editing, the
Visual Packet
Builder
tool is also available; click on the corresponding button to invoke
it.
You can also click on the button with an arrow on it to display the
list of available packet templates. The program comes with
TCP,
UDP,
and
ICMP
packet templates; using them is often faster than typing hex codes
in the editor window. These templates contain typical TCP, UDP, and
ICMP packets, but you would most probably want to edit many packet
fields and use meaningful values that suit your needs, such as real
MAC and IP addresses, port numbers, SEQ and ACK numbers, etc. You
can use your own templates rather than the built-in ones. You can
drag-and-drop a packet from the CommView Packets tab to the
Templates section in the Packet Generator window. If you drop
several packets into the Templates section, only the first packet
will be used as a template. An entry named New Template will appear
in the list of templates. You can rename a template by
right-clicking on it in the list and selecting
Rename.
If you need to delete a template, right-click on it and
select
Delete
from the pop-up menu. Selecting a template in the list will load
the packet that it contains in the editor window where it can be
edited prior to sending.
You can also place NCFX files with the templates of your choice to
the TEMPLATES subfolder in the application folder. If CommView
finds NCFX files (or just one of them) in the TEMPLATES subfolder,
it will list them among the available templates in the drop-down
list. These NCFX files should contain only one packet per file, but
if you use a file that contains many packets, CommView will load
only the first one.
Once you have edited a packet, use the controls below to send
it:
Packet Size
– modifies the packet size.
Packets Per Second
– controls the speed at which packets will be sent.
Continuously
– select this option if you want the Packet Generator to send
packets continuously until you click Stop.
Time(s)
– select this option if you want the Packet Generator to send
packet a given number of times.
802.11 rate
– modifies the 802.11 rate to be used for sending packets.
Depending on the currently selected band and channel, not all rates
may be used. For example, 802.11a packets cannot be sent at the
rate of 2 Mbps.
Long/Short Preamble
– sets the preamble type for 802.11b and 802.11g packets. Not
applicable to 802.11a.
Send/Stop
– click this button when you are ready to send packets or to stop
sending them.
Working with multiple packets
You can use the Packet Generator to send multiple packets at once.
To do that, just select the packets you want to send in the list
and invoke the Packet Generator using the right-click menu, or drag
and drop the selected packets to the Packet Generator window.
Alternatively, you can drag and drop capture files in all supported
formats directly to the Packet Generator window. When multiple
packets are being sent, the packer editor and decoder tree become
invisible.
Saving edited packets
If you edited a packet and would like to save it, just drag the
decoder tree to the desktop or any folder, and a new file in NCFX
format containing the packet will be created. The file name is
always PACKET.NCFX. You can also drag the packet to the templates
window. If you need to edit and send multiple packets, edit them
one by one, each time dragging a new packet to the desktop and
renaming it. After that, open a new Log Viewer window, drag-n-drop
the edited packets from the desktop to Log Viewer, select them
using the Shift button, and invoke the Packet Generator using the
context menu.
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