Lucian,
> My intention is to build a personal firewall but only for a LAN
> netcard (I have read about the leak of PPP standardisation but
> that is not a problem for me). There are some other reasons for
> I can't build a firewall?
The Pcap library (for UNIX), and its Windows equivalent, WinPcap,
are libraries to help the programmer work with the sending and
receiving of raw network packets, indepent from the rest of the
operating system.
Examples of such applications are Ethereal and TCPdump (these just
listen to the network cards and display any packets received), tools
like Nmap which send and receive packets, and programs to implement
"strange" network protocols that do not need any operating system
kernel support.
Because these libraries operating *alongside* the operating system,
they can never *interfere* with what the operating system does with
network packets, and this is exactly what a network firewall has to
do: it has to allow or disallow packets, based on filters and/or
history.
Therefore, you cannot use the Pcap libraries for writing a firewall.
Sorry,
Fred
================================================================= This is the WinPcap
users list. It is archived at
http://www.mail-archive.com/[EMAIL PROTECTED]/
To unsubscribe use
mailto: [EMAIL PROTECTED]
=================================================================
