Re: how to block udp frag?

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the iptables dont see this traffic..


On Sat, 1 Jan 2005 19:08:45 -0500, Jason Opperisano <opie@xxxxxxxxxxx> wrote:
> On Sat, Jan 01, 2005 at 09:58:41PM -0200, Bruno Wallace wrote:
> > hello,
> > how to block this?????
> >
> > 20:53:44.628586 83.102.166.15 > xxx.xxx.151.35: udp (frag 1720:25@512)
> > (ttl 53, len 45)
> > 0x0000   4500 002d 06b8 0040 3511 2599 5366 a60f        E..-...@5.%.Sf..
> > 0x0010   c896 9723 11ef 0035 0019 1e70 71f7 0100        ...#...5...pq...
> > 0x0020   0001 0000 0000 0000 0000 0200 0100             ..............
> > 20:53:47.197264 83.102.166.24 > xxx.xxx.151.34: udp (frag
> > 48577:25@512) (ttl 53, len 45)
> > 0x0000   4500 002d bdc1 0040 3511 6e87 5366 a618        E..-...@xxxxxxxx
> > 0x0010   c896 9722 11ef 0035 0019 1e68 71f7 0100        ..."...5...hq...
> > 0x0020   0001 0000 0000 0000 0000 0200 0100             ..............
> > 20:53:49.306206 83.102.166.76 > xxx.xxx.145.115: udp (frag
> > 21990:25@512) (ttl 53, len 45)
> > 0x0000   4500 002d 55e6 0040 3511 dbdd 5366 a64c        E..-U..@xxxxxxxx
> > 0x0010   c896 9173 11ef 0035 0019 23e3 71f7 0100        ...s...5..#.q...
> > 0x0020   0001 0000 0000 0000 0000 0200 0100             ..............
> > 20:53:49.529603 83.102.166.7 > xxx.xxx.146.119: udp (frag
> > 26427:25@512) (ttl 53, len 45)
> > 0x0000   4500 002d 673b 0040 3511 c9c9 5366 a607        E..-g;.@xxxxxxxx
> > 0x0010   c896 9277 11ef 0035 0019 2324 71f7 0100        ...w...5..#$q...
> > 0x0020   0001 0000 0000 0000 0000 0200 0100
> >
> > thanks
> > Bruno Wallace
> 
> either (a) use a default deny policy that doesn't allow UDP traffic or
> (b) in your rules where you accept UDP traffic, specify "! -f" which,
> according to the man page:
> 
>   When the "!" argument precedes the "-f" flag, the rule will only match
>   head  fragments, or unfragmented packets.
> 
> -j
> 
> 


-- 
abraço,
Bruno Wallace



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