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Timeline for answer to ICMP Echo Response IP Header Copying by Zac67

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May 29, 2025 at 16:51 comment added Zac67 RfCs are usually rather explicit - hard to tell for this really ancient one though. My money is on if you'd have to copy the IP header even this old RfC or one of its updates would clearly say so. Also, copying all optional headers indiscriminately could create security issues for reflections attacks, so it's not the wise thing to do.
May 29, 2025 at 15:10 comment added WakkaTrout Are we sure that is really a help though and not a requirement of the RFC? Both Linux and lwIP seems to copy the the whole header, switching the destination address and source address, resetting the TTL, and recomputing the checksum. github.com/torvalds/linux/blob/master/net/ipv4/icmp.c#L400 from request to reply. github.com/lwip-tcpip/lwip/blob/…
May 29, 2025 at 10:11 history edited Zac67 CC BY-SA 4.0
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May 29, 2025 at 8:27 history answered Zac67 CC BY-SA 4.0