in reply to Re^2: Insert the 4th TCP packet after TCP three-times handshakes
in thread Insert the 4th TCP packet after TCP three-times handshakes

If the initial sequence number of the other side could be predicted, blind tcp initial and inject(use a source ip address that not alive)may be possible.
  • Comment on Re^3: Insert the 4th TCP packet after TCP three-times handshakes

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Re^4: Insert the 4th TCP packet after TCP three-times handshakes
by cazz (Pilgrim) on May 03, 2005 at 15:04 UTC
    There are lots of things good & bad that could be done with injecting of packets. The code does a connect, and then sends a packet by hand on its own connection. Sure, if the code looked for a handshake without creating one, then I could see claiming this code was evil, but thats not what this code does.
Re^4: Insert the 4th TCP packet after TCP three-times handshakes
by merlyn (Sage) on May 03, 2005 at 15:51 UTC
    If the initial sequence number of the other side could be predicted, blind tcp initial and inject(use a source ip address that not alive)may be possible.
    See, now you've gone and set off my spidey sense again. Here you are, supporting my argument that you're up to no good with this code.

    If thre's a legitimate use for this code, would you please explain it?

    -- Randal L. Schwartz, Perl hacker
    Be sure to read my standard disclaimer if this is a reply.

Re^4: Insert the 4th TCP packet after TCP three-times handshakes
by shanleiguang (Initiate) on May 03, 2005 at 23:55 UTC
    this script maybe useful to learn TCP/IP, so i post here