Re: Invalid ICMP type 69

in reply to Invalid ICMP type 69

I'm far from a pack/unpack expert, but isn't the ICMP type only one byte?

Yup, it is.

I'd suggest taking another look at your unpack templates, perhaps.

Mike

Comment on Re: Invalid ICMP type 69

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Re^2: Invalid ICMP type 69 by vancetech (Beadle) on Nov 03, 2006 at 20:51 UTC
After looking at Net::Ping I can see that the received ICMP packet type data starts 20 bytes into the packet. The following code sucessfully unpacks the ICMP Type and Sub-Code. `my($fromtype, $fromsubcode) = unpack("C2", substr($icmpbuffer, 20, 2) +);` [download] Likewise, the NetPacket::ICMP->decode() function requires the same section of the packet and not the full packet that is returned. I wonder what the first portion of the packet is.	[reply] [d/l]
Re^3: Invalid ICMP type 69 by NetWallah (Canon) on Nov 04, 2006 at 01:31 UTC
The first 20 bytes are the IP header. You should be able to use NetPacket::IP to analyze the whole packet, and extract the ICMP payload using `$icmp_data = NetPacket::IP::strip($raw_pkt);` [download] For details on constructing/analyzing ICMP packets, see http://www.goldfish.org/books/TCPIP Illustrated Vol 1/icmp_int.htm . "A closed mouth gathers no feet." --Unknown	[reply] [d/l]

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