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A comment on AT&T Fiber in the SF Bay Area is flipping bits. Parent comment

Re:AT&T Fiber in the SF Bay Area is flipping bits by noncoml on Monday December 07, 2020 @11:49PM (#25341973)
To my knowledge, from working on an actual software router, a router will only touch the TTL and recalculate the IP header checksum.

There is no reason for it to touch the TCP header.

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Re:AT&T Fiber in the SF Bay Area is flipping bits by garmaine on Tuesday December 08, 2020 @12:21AM (#25342196)
Agreed there is no logical reason for it to touch the TCP header.

And yet, an unfortunate number of L2 switches do exactly that. :(

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Re:AT&T Fiber in the SF Bay Area is flipping bits by Thorrez on Tuesday December 08, 2020 @01:10AM (#25342420)
Doesn't NAT (specifically carrier-grade NAT in this case) often modify the port? Although I don't know if AT&T does carrier-grade NAT.

https://en.wikipedia.org/wiki/Carrier-grade_NAT

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Re:AT&T Fiber in the SF Bay Area is flipping bits by noncoml on Tuesday December 08, 2020 @01:26AM (#25342490)
> an unfortunate number of L2 switches do exactly that

Can you name any? Just curious

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