Connected TCP socket receives packet without timestamps option which exists in SYN, SYNACK and ACK. It is packet 4 in attached tcpdump output. tcpdump output description: The host has address 10.208.10.1 (server) and the peer host has address 10.208.10.2 (client). Establishing connection: Timestamps option exists in SYN, SYNACK and ACK (packets 1, 2 and 3 in attached file), so accepted socket should receive packets only with timestamps option. Sending packet: the socket receives the packet without timestamps option (packet 4 in attached file), i.e. recv() function called on the socket receives the data from the packet. The "strange" packet is generated using PCAP. I see this behaviour on 2.6.26 and on 3.14 kernels.