Hello! > The server socket sockopt are all default, except for the > TCP_WINDOW_CLAMP which is set to 1400 (application specific). It is definitely not all. If you do not fiddle with SO_RCVBUF also, you will always have receiver advertising window of 1400. 11:15:00.922119 IP 10.10.10.3.1150 > 10.10.10.2.3200: S 2246605788:2246605788(0) win 6144 <mss 1460,nop,wscale 0,nop,nop,timestamp 3248699 0> 11:15:00.922791 IP 10.10.10.2.3200 > 10.10.10.3.1150: S 3863556410:3863556410(0) ack 2246605789 win 1400 <mss 1460,nop,nop,timestamp 268188460 3248699,nop,wscale 0> 11:15:00.923118 IP 10.10.10.3.1150 > 10.10.10.2.3200: . ack 1 win 6144 <nop,nop,timestamp 3248699 268188460> 11:15:00.923486 IP 10.10.10.3.1150 > 10.10.10.2.3200: P 1:7(6) ack 1 win 6144 <nop,nop,timestamp 3248699 268188460> 11:15:00.924143 IP 10.10.10.2.3200 > 10.10.10.3.1150: . ack 7 win 1394 <nop,nop,timestamp 268188460 3248699> cannot happen. SO_RCVBUF is not default. Alexey - : send the line "unsubscribe linux-net" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html