modify Ethernet FSC in Scapy

Question

I need to send malformed Ethernet frames for testing purposes. I have disabled offload for Rx and Tx checksums:

root@T60:~# ethtool --show-offload eth0
Features for eth0:
rx-checksumming: off
tx-checksumming: off
    tx-checksum-ipv4: off [fixed]
    tx-checksum-unneeded: off [fixed]
    tx-checksum-ip-generic: off
    tx-checksum-ipv6: off [fixed]
    tx-checksum-fcoe-crc: off [fixed]
    tx-checksum-sctp: off [fixed]

However, does this offloading involve only IP, TCP and UDP checksums? Is it possible to send frames with malformed Frame Sequence Check in Ethernet footer using Scapy? I highly doubt in this as calculating the Ethernet FSC is probably implemented in NIC hardware?

Answer 1

1. YES , the NIC offover just off ether, IP, TCP, UDP 's checksum, and UDP checksum is checked seldom.

2. YES, SCAPY can assembly packet even it's bad checksum by using raw socket

3. just try la :)