Messages in this thread | | | Date | Mon, 4 Oct 1999 17:51:28 +0400 | From | Savochkin Andrey Vladimirovich <> | Subject | Re: predictable IP ID |
| |
On Mon, Oct 04, 1999 at 02:26:31PM +0100, Alan Cox wrote: > > Predictable IP IDs is not just a question about losing packets because > > attackers can create junk fragments. > > Oh not this one again. > > The checksum of the tcp header or UDP header covers the entire packet after > reassembly. That means that feeding in a corrupt fragment causes a checksum > failure and packet discard. > > The original TCP authors had that one covered. IP sequence space is shorter > than max ttl so all protocols need to be robust against suprise > fragment delivery.
Alan, I completely understand this issue. I'm not so ignorant ;-) And attacks on the defragmentation process WAS NOT a reason to write the patch.
> > numbers. Tools exploiting this weakness already exist. See > > http://www.securityfocus.com/templates/archive.pike?list=1&date=1999-08-1&msg=BUGTRAQ%251999080211573830@LISTS.SECURITYFOCUS.COM > > > > This URL has nothing to do with IP sequence guessing. It references some old > unrelated 2.0.3x thing.
I suppose you haven't read all the detals. The problem isn't related to 2.0.3x - it well applies to 2.3.18 kernel. It's a rather fresh idea (I haven't heard about it before this August) about TCP spoofing attack based exactly on predictable IP IDs.
Best regards Andrey
- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.rutgers.edu Please read the FAQ at http://www.tux.org/lkml/
| |