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    <p>The problem is that you're quoting the 8-byte header payload from <a href="http://tools.ietf.org/html/rfc792" rel="noreferrer">RFC 792, Page 4</a>, but the requirements were changed by RFC 1812...</p> <pre><code>Time Exceeded Message (in RFC 792) 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Code | Checksum | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | unused | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Internet Header + 64 bits of Original Data Datagram | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ </code></pre> <p><a href="http://tools.ietf.org/html/rfc1812#section-4.3.2.3" rel="noreferrer">RFC 1812, Section 4.3.2.3</a> dramatically increases the allowable payload in an ICMP Error message (emphasis mine):</p> <blockquote> <p><strong>4.3.2.3 Original Message Header</strong></p> <p>Historically, every ICMP error message has included the Internet header and at least the first 8 data bytes of the datagram that triggered the error. This is no longer adequate, due to the use of IP-in-IP tunneling and other technologies. <em>Therefore, the ICMP datagram SHOULD contain as much of the original datagram as possible without the length of the ICMP datagram exceeding 576 bytes</em>. The returned IP header (and user data) MUST be identical to that which was received, except that the router is not required to undo any modifications to the IP header that are normally performed in forwarding that were performed before the error was detected (e.g., decrementing the TTL, or updating options).</p> </blockquote> <p>The ICMP Errors you're generating from Scapy packets should contain all the information from the IP and TCP layers of the original packet.</p>
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    1. USMike Pennington
    1. USMike Pennington
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    1. COThank you. I "manually" matched data packets and their time-exceeded ICMP messages, only to find out that I was getting one match for each TCP packet if the ICMP payload considered was 28B long and when I considered more than 28B, I hardly ever got a match. I really think it has something to do with the library I'm using to inspect packets (Scapy). I wrote something more in answer to stuart's reply.
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      1. USRicky Robinson
    2. COI am curious, is responding to the one-byte payload difference part of the bounty award, or was the reference for the payload size sufficient?
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      1. USMike Pennington
    3. COIf you could help with that thing too, it'd be great. Otherwise, no worries!
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