lets say I have client > firewall > server . firewall is doing nat , my concern is how the checksum at network layer will be calculated . when client will generate a packet and put the checksum info into the header , since the firewall is doing NAT it will change IP header info so when the server receives will it discard the packet because of checksum ?? or is it job of the firewall or any other network device to update the checksum as well if its doing NAT ? if this is the case then in real world scenario , checksum will be calculated and updated ( if required ) at each network device . asked 14 May '15, 23:57  tech round |
One Answer:
Yes.
every network device that changes parts of the frame, that require recalculation of the checksum, will HAVE TO generate a new checksum, otherwise it will cause massive problems on the network. Regards answered 15 May '15, 01:20  Kurt Knochner ♦ edited 15 May '15, 01:20 |
Thanks Kurt :)
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