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Computing the checksum after changing the packet's fields

Nov 1, 2009 at 9:33 AM


I getting a packet from a pcap file and changing the source/destination.

Packet newpacket = PacketBuilder.EthernetIpV4(DateTime.Now, source, destination, packet.Ethernet.IpV4.TypeOfService, packet.Ethernet.IpV4.Identification, packet.Ethernet.IpV4.Fragmentation, packet.Ethernet.IpV4.Ttl, packet.Ethernet.IpV4.Protocol, new1, new2, packet.Ethernet.IpV4.Options, ethernetPayload);


How can I recalculate the checksum before sending  the packet?





Nov 1, 2009 at 6:33 PM
Edited Nov 1, 2009 at 6:33 PM



The IPv4 checksum is automatically calculated to be correct when you build a new packet using the PacketBuilder.EthernetIpV4() method.