I am doing some TCP related experiment between two virtualbox VMs. On the client side, I sent out a TCP syn packet with the MSS option of 1400 bytes. However, it seems that the server (sender) ignored this option and sent out a packet with very large payload, something like 10000+ bytes.Why didn't the MSS option honored by the server? BTW, the server is a Nginx server.
Below this some PCAP showing the problem. First is the SYN packet with MSS = 1400.
Second is the payload sent by the server:
As can be seen that the payload size is 11200.
BTW the MTU on the interface is 1500 bytes.
Thanks.
By discussion with Jim.The issue this LRO/GRO. Please turn that off if we want to see the packets as they appears on the wire.