65 lines
2.4 KiB
Plaintext
65 lines
2.4 KiB
Plaintext
The following instructions apply if you have a Linux platform and want
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libpcap to support the 'ACN' WAN/LAN router product from SITA
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(http://www.sita.aero)
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This might also work on non-Linux Unix-compatible platforms, but that
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has not been tested.
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See also the libpcap INSTALL.txt file for further libpcap configuration
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options.
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These additions/extensions have been made to PCAP to allow it to
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capture packets from a SITA ACN device (and potentially others).
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To enable its support you need to ensure that the distribution has
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a correct configure.ac file; that can be created if neccessay by
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using the normal autoconf procedure of:
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aclocal
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autoconf
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autoheader
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automake
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Then run configure with the 'sita' option:
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./configure --with-sita
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Applications built with libpcap configured in this way will only detect SITA
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ACN interfaces and will not capture from the native OS packet stream.
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The SITA extension provides a remote datascope operation for capturing
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both WAN and LAN protocols. It effectively splits the operation of
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PCAP into two halves. The top layer performs the majority of the
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work, but interfaces via a TCP session to remote agents that
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provide the lower layer functionality of actual sniffing and
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filtering. More detailed information regarding the functions and
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inter-device protocol and naming conventions are described in detail
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in 'pcap-sita.html'.
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pcap_findalldevs() reads the local system's /etc/hosts file looking
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for host names that match the format of IOP type devices. ie. aaa_I_x_y
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and then queries each associated IP address for a list of its WAN and
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LAN devices. The local system the aggregates the lists obtained from
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each IOP, sorts it, and provides it (to Wireshark et.al) as the
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list of monitorable interfaces.
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Once a valid interface has been selected, pcap_open() is called
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which opens a TCP session (to a well known port) on the target IOP
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and tells it to start monitoring.
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All captured packets are then forwarded across that TCP session
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back to the local 'top layer' for forwarding to the actual
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sniffing program (wireshark...)
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Note that the DLT_SITA link-layer type includes a proprietary header
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that is documented as part of the SITA dissector of Wireshark and is
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also described in 'pcap-sita.html' for posterity sake.
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That header provides:
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- Packet direction (in/out) (1 octet)
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- Link layer hardware signal status (1 octet)
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- Transmit/Receive error status (2 octets)
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- Encapsulated WAN protocol ID (1 octet)
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