3 ms·

I’ve had a case where a bit flip in a TCP stream was not caught because it happened in a Singapore government deep packet inspection snoop gateway that recalcul

by fmajid 5y ago

I’ve had a case where a bit flip in a TCP stream was not caught because it happened in a Singapore government deep packet inspection snoop gateway that recalculated the TCP checksum for the bit-flipped segment: https://blog.majid.info/telco-snooping/ https://blog.majid.info/telco-snooping/

brokenmachine 5y ago
Nice article, enjoyed it.
- fmajid 5y ago
  Thanks!
kingosticks 5y ago
Sorry if this is obvious, but how do we know this isn't due to something more "innocent" like fragmentation?
- fmajid 5y ago
  Fragmentation doesn’t change the TCP checksum. The packet is reassembled and the original checksum verified against the rehydrated packet and TCP segment.