-2

i've coded some program which pretends to stablish a connection, and then send a packet of data; by using raw-sockets in linux, and the C language.

afortunately, i've implemented okay the program, since a connection is stablished. The problem i've now is that i can not spend so much time, for guessing how a psh-ack (data packet) must be filled, by receiving the ACK from server, and also to can see the data onto the netcat's output buffer...

so, please, can anyone help to format the packet? I've spent so many time, and giving you a complete log of the traffic would be easy.

Thanks in advance. Hope a suggestion in an early time... ;).

P.S: if not clear, i pretend to implement my own user-space tcp stack just for speedy up the processes of tcp networking, just for embed a networking process in a non-blocking program execution, and a fast resultset of networking processes.

As some of you may be know, linux boxes automagically sends an answer to a server which sent and SYN_ACK, but RST the connection, and making not possible to stablish a connection by implementing the TCP stack. So, I should say, I'm using the grsec's protection called: "TCP/UDP blackhole DoS prevention", which prevents the Linux Kernel of sending not wished responses to "incoherent" network traffic.

That's all.

user1189104
  • 79
  • 1
  • 6

1 Answers1

0
ip.len = tcp_data_sz + tcphdr_sz + iphdr_sz

tcp.id = id + 1
tcp.seq = same as ACK of three way handshake
tcp.ack_seq = same as ACK of three way handshake

pseudo_hdr.len = tcp_data_sz + tcphdr_sz

tcp.check = (size: psehdr + tcphdr + tcpdata) (pad with 00's until size % 2 = 0).

this links was useful: http://www.arcesio.net/checksum/checksumTCP.html (in spanish most & english edited).

thanks all 4 watching.

Linuxios: thanks for your great comment, now i found my solution my own way. (my method is faster than common linux interface :).

user1189104
  • 79
  • 1
  • 6