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Visual Packet Builder is a tool designed for facilitating packet
editing and generation in the
Packet
Generator.
This tool allows you to quickly and correctly create a new packet
or modify an existing one using ready-made templates. Once created
or edited, a packet can be injected into the network using
the
Packet
Generator.
Standard TCP, UDP, and ICMP (based on the 4th and 6th versions of
IP protocol), and ARP packet generation is supported. To create a
packet, select its type from the
Packet Type
drop-down list. The default values of the packet fields will be
automatically filled in, but can be changed afterwards.
ICMP, TCP, UDP, and ARP packets consist of several encapsulated
layers, and the interface of Visual Packet Builder is arranged the
same way. Options that correspond to the same layer are located on
a separate panel. For example, a TCP packet consists of 4 layers;
the
Source MAC
and
Destination MAC
address fields are located on the
Ethernet II
panel (Data link layer), and
Src Port
and
Dst Port
values are located on the TCP panel (Transport layer). If you'd
like to hide a panel, click the
Expand/Collapse
button located in the right corner of the panel header.
Note that some "parental" layer values affect the packet type on
lower layers; hence modifying upper layers may lead to rebuilding
the lower layers of a packet. Therefore, if you change the
Protocol
type in the
Ethernet II
panel (Data link layer), it will lead to rebuilding the whole
packet. Another peculiarity that you should keep in mind is that
the values of some fields depend on the contents of other fields,
as well as the data contents of the lower layers. Such fields are:
checksums and header lengths, and/or data of lower layers. Visual
Packet Builder calculates such values automatically. However, when
creating non-standard packets, you may want to specify different
values manually by checking the
Override default value
box and specifying the desired values.
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IMPORTANT:
Visual Builder helps you control the correctness of the packet
being built by highlighting the headers and fields with incorrect
or non-standard values in red.
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Despite the fact that Visual Packet Builder has internal support
for TCP, UDP, ICMP and ARP protocols only, you can still use it to
edit packets that use other protocols. For such packets, you can
use the hex editor to modify the data.
Once created, a packet can be saved and subsequently loaded to
Visual Packet Builder again. Use the respective commands located in
the
File
menu of Visual Packet Builder for loading/saving capture files. You
can load any CommView capture file (NCFX); however, if the file
contains more than one packet, only the first one will be
loaded.
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