1 The following instructions apply if you have a Linux platform and want 2 libpcap to support the 'ACN' WAN/LAN router product from from SITA 3 (http://www.sita.aero) 4 5 This might also work on non-Linux Unix-compatible platforms, but that 6 has not been tested. 7 8 See also the libpcap INSTALL.txt file for further libpcap configuration 9 options. 10 11 These additions/extensions have been made to PCAP to allow it to 12 capture packets from a SITA ACN device (and potentially others). 13 14 To enable its support you need to ensure that the distribution has 15 a correct configure.ac file; that can be created if neccessay by 16 using the normal autoconf procedure of: 17 18 aclocal 19 autoconf 20 autoheader 21 automake 22 23 Then run configure with the 'sita' option: 24 25 ./configure --with-sita 26 27 Applications built with libpcap configured in this way will only detect SITA 28 ACN interfaces and will not capture from the native OS packet stream. 29 30 The SITA extension provides a remote datascope operation for capturing 31 both WAN and LAN protocols. It effectively splits the operation of 32 PCAP into two halves. The top layer performs the majority of the 33 work, but interfaces via a TCP session to remote agents that 34 provide the lower layer functionality of actual sniffing and 35 filtering. More detailed information regarding the functions and 36 inter-device protocol and naming conventions are described in detail 37 in 'pcap-sita.html'. 38 39 pcap_findalldevs() reads the local system's /etc/hosts file looking 40 for host names that match the format of IOP type devices. ie. aaa_I_x_y 41 and then queries each associated IP address for a list of its WAN and 42 LAN devices. The local system the aggregates the lists obtained from 43 each IOP, sorts it, and provides it (to Wireshark et.al) as the 44 list of monitorable interfaces. 45 46 Once a valid interface has been selected, pcap_open() is called 47 which opens a TCP session (to a well known port) on the target IOP 48 and tells it to start monitoring. 49 50 All captured packets are then forwarded across that TCP session 51 back to the local 'top layer' for forwarding to the actual 52 sniffing program (wireshark...) 53 54 Note that the DLT_SITA link-layer type includes a proprietary header 55 that is documented as part of the SITA dissector of Wireshark and is 56 also described in 'pcap-sita.html' for posterity sake. 57 58 That header provides: 59 - Packet direction (in/out) (1 octet) 60 - Link layer hardware signal status (1 octet) 61 - Transmit/Receive error status (2 octets) 62 - Encapsulated WAN protocol ID (1 octet) 63 64 65
