Re: Linux Sequence Number Generation

"Sunny" <sun4udee@xxxxxxxxx> writes:

> Hello,
> Can anybody tell me about Linux 2.6 sequence number
> generation???
> Suppose i caught a packet using PRE_ROUTING hook and i want to modify
> the packet that will be response for our caught packet.. So how can I
> map an outgoing packet (a reply) to a recieved packet..

What sequence numbers are you talking about? TCP sequence numbers?

The mapping of the reply to the request is done by taking the ACK
value of the incoming packet and using that for the sequence number
for the reply packet.

More on the topic of tcp spoofing here and other places
http://www.signaltonoise.net/library/ipsp00f.htm


Best Regards,
--
Todd H.
http://www.toddh.net/
.

Relevant Pages

  • RE: IP Session Hijacking And Spoofing
    ... can use B as the bogus source address. ... A sends a SYN packet to T with B's address as the source to open a TCP ... Any sequence number will work in this packet. ... IP Session Hijacking And Spoofing ...
    (Security-Basics)
  • Re: [Full-Disclosure] IETF Draft - Fix for TCP vulnerability (fwd)
    ... >> FreeBSD host is sending a FIN to close an established connection, ... >> the peer host adding the window size advertised in the FIN packet to the ... >> sequence number acknowledged in the FIN packet, and using the sum as the ...
    (FreeBSD-Security)
  • Re: TCPIP sequence number question
    ... How will the receiver behave upon receiving the packet with sequence ... Since TCP uses a sliding window, a lot of data can be outstanding at the time of a retransmission. ... And this is normally all regulated by the amount of retransmissions you get. ...
    (comp.os.vms)
  • Re: tcp vulnerability? havent seen anything on it here...
    ... >> windows, the propability of guessing the right sequence number is not ... sending a corrective "ACK" packet back. ... send the line "unsubscribe linux-kernel" in ...
    (Linux-Kernel)
  • Re: recvfrom() strange operation
    ... I have only one escape way for this kind of UDP operation. ... TCP receive you always send data to upper level in sequence, ... In case of UDP you do not know the packet ...
    (comp.os.linux.development.system)