Filter

How do I know what packet is triggering the call?

If the user already knows the protocol type, the source port and the IP address of the packet that is triggering the call, he can design the filter rule based on these information. Otherwise, he can take a look at the SMT Menu 24.1 to see what is the exact packet that triggers the outgoing call. The 'LAN Packet Which Triggered Last Call' status in Menu 24.1 will show you the packet which triggers the call. A display of the header of the packets is shown next.

`LAN Packet which Triggered Last Call: (Type: IP)` `45 00 00 2E CA 0E 40 00 1F 06 D7 09 CC F7 CB B4 CC D9 00 02 04 1C 00 15` `00 33 2D 5E 55 80 B5 C0 50 18 1F 9B E7 D4 00 00 50 41 53 56 0D 0A`

We list the header of the IP, UDP and TCP in order to make you know more about the format of the IP packet and IPX packet in Menu 24.1 for easy configuration of a filter rule.

IP Header

0 15 16 31

4-bit version | 4-bit length | 8-bit type of service (TOS) | 16-bit total length (in bytes)
16-bit identification | 3-bit flag | 13-bit fragment offset
8-bit time to live(TTL) | 8-bit protocol | 16-bit header checksum
32-bit source IP address
32-bit destination IP address
Option (if any)
Data

UDP Header

0 15 16 31

16-bit source port number | 16-bit destination port number
16-bit UDP length | 16-bit UDP checksum
Data (if any)

TCP Header

0 15 16 31

16-bit source port number | 16-bit destination port number
32-bit sequence number
32-bit acknowledgment number
4-bit header length | Reserved (6 bits) | U R G | A C K | P S H | R S T | S Y N | F I N | 16-bit window size
16-bit TCP checksum | 16-bit urgent pointer
Option (if any)
Data (if any)

Based on the above headers, we can then interpret the LAN Packet Which Triggered Last Call as following:

`LAN Packet which Triggered Last Call : (Type: IP)` `45 00 00 2E CA 0E 40 00 1F 06 D7 09 CC F7 CB B4 CC D9 00 02 04 1C 00 15`

06 = TCP Protocol
`CC F7 CB B4`= 204.247.203.180 = Source IP
`CC D9 00 02`= 204.217.0.2 = Destination IP
`04 1C`=1052(dec)= Source port number
`00 15`= 21(dec)=Destination port number = FTP port

IPX header in Menu 24.1:

`LAN Packet Which Triggered Last Call: (Type: IPX)` `00 28 01 01 00 00 00 00 FF FF FF FF FF FF 04 53 00 00 00 00 00 00 00 00 00 0004 53 00 01 FF FF FF FF FF 00 00 00 00`

`01 IPX packet type`
`00 00 00 00 Destination network number`
`FF FF FF FF FF FF Destination node number`
`04 53 Destination socket number`
`00 00 00 00 Source network number`
`00 00 00 00 00 00 Source node number`
`04 53 Source socket number`

IPX packet type:

01=RIP
02=echo
03=error
04=SAP
05=SPX
11=NCP
14=NetBIOS

Socket number:

0451=NCP
0451=SAP
0453=RIP
0455=NetBIOS

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