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CommView
provides a simple TCP/IP interface that allows you to process
packets captured by CommView using your own application in real
time. Starting with version 5.0 you may also use this interface for
sending packets (similar to the Packet Generator function in
CommView).
Please note
that the data format has changed compared to the previous versions
of CommView. The TS switch has also been eliminated as all the
information about a packet including the timestamp is now sent in
the header.
How It Works
CommView
should be launched with a special command-line argument, "MIRROR",
that tells the program to mirror captured packets to an IP address
and TCP port of your choice.
Examples:
CV.EXE
mirror:127.0.0.1:5555 // mirrors packets to the loopback
address, TCP port 5555
CV.EXE
mirror:192.169.0.2:10200 // mirrors packets to 192.169.0.2,
TCP port 10200
When CommView
is launched with a switch like this, it tries to establish a TCP
session by connecting to the specified IP address and port number.
It means that you should already have your application running and
listening on the specified port. If CommView fails to establish a
connection, it will keep on trying to connect every 15 seconds. The
same happens if the connection is broken: CommView will try to
re-establish it every 15 seconds. If the connection is successfully
established, CommView sends the packets it captures to the
specified IP address as they arrive, in real time.
Data Format
The data is
transmitted in NCF format. Please refer to the
CommView Log Files
Format chapter for the format
description.
Sending Packets
Packets may
not only be received by your application, but also sent as if you
were using Packet Generator. Data can be sent to CommView using the
same TCP connection over which you are receiving the data. The data
format is simple: You should send the packet length (a two-byte
unsigned integer in the standard little-endian byte order) followed
by the packet itself. If the adapter is not opened or it does not
support packet injection, the packet is silently discarded.
Sample Projects
Two simple
demo applications that listen for inbound connections, extract
packets from the stream, and display raw data are available.
Bandwidth
When mirroring
data to a remote computer, make sure that the link between CommView
and the computer to which the data is being mirrored is fast enough
to transfer all the data being captured. If CommView captures 500
Kbytes/sec, and your link can handle only 50 Kbytes/sec, you'd
inevitably have "traffic jams", which might result in various
problems (e.g., Winsock may just stop sending data under some
Windows versions). If you are looking for a more flexible solution
that would feature smart buffering and remote control, consider
using
CommView Remote
Agent.
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