n the MITM attack code, the attacker tries to modify the packets from A to B

$.$

$$After intercepting such a packet, the attacker makes a copy of the packet, and then does the following. Why does the attacker have to delete the IP and TCP checksums?

newpkt

$=$

$$IP

$($

bytes

$($

pkt

$[$

IP

$]$

$)$

$)$

del

$($

newpkt

$.$

$$icIhksum

$)$

del

$($

newpkt

$[$

TCP

$]$

$.$

chksum

$)$