[Snort-users] Where or how to interpret this

./ dotslash at ...1760...
Sun Apr 8 13:01:32 EDT 2001


Very interesting.

However, in future "attacks" like this how can I tell by myself of such
activity?  Is there a website to learn this from or a book from Amazon
(could also be on my wishlist :-) ?



----- Original Message -----
From: "shawn . moyer" <shawn at ...1184...>
To: "./" <dotslash at ...1760...>
Cc: <snort-users at lists.sourceforge.net>
Sent: Sunday, April 08, 2001 3:37 AM
Subject: Re: [Snort-users] Where or how to interpret this


>
> This will usually be a box sending a response packet back to a machine
> on your net on a port that it doesn't like -- some IP stacks are
> configured to use a specific range of ports for response packets
> (generally something like 1024-32767), and if something responds to a
> funky port the box will send an unreachable message.
>
> This could also be someone attempting to connect to a service on a box
> that doesn't exist, followed by the box's response back saying that port
> isn't open.
>
> Generally it's a good practice to drop these messages at the firewall,
> since they give more information back to a potential attacker than you
> might want to send, i.e. even stating whether a service is unavailable
> or not is giving out info "for free" about your network. Dropping these
> can break some protocols, though, specifically active FTP.
>
>
>
> --shawn
>
> "./" wrote:
> >
> > Right.  I've converted my snort log (snort -r ) and got this among other
> > things.  I just want to know how (or where) I can interpret this:
> >
> > 04/07-19:33:15.831746 xx.xx.xx.xx -> yy.yy.yy.yy
> > ICMP TTL:128 TOS:0x0 ID:58635 IpLen:20 DgmLen:56
> > Type:3  Code:3  DESTINATION UNREACHABLE: PORT UNREACHABLE
> > ** ORIGINAL DATAGRAM DUMP:
> > yy.yy.yy.yy:53 -> xx.xx.xx.xx:17418
> > UDP TTL:239 TOS:0x0 ID:63931 IpLen:20 DgmLen:158
> > Len: 138
> > ** END OF DUMP
> >
> > where xx = internal and yy = external.
> >
> > --
> > "The circumstances of ones birth are irrelevant.
> > It is what you do with the gift of life that
> > determines who you are."  -- MewTwo
> >
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>
> --
>
> s h a w n   m o y e r
> shawn at ...1184...
>
> "Nuclear war would really set back cable."
>                              -- Ted Turner





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