Messages in this thread | | | Date | Wed, 17 Jan 2001 18:35:47 +0100 | From | Andi Kleen <> | Subject | Re: IP defrag (was RE: ipchains blocking port 65535) |
| |
On Wed, Jan 17, 2001 at 05:15:54PM -0000, Tony Gale wrote: > > On 17-Jan-2001 Jussi Hamalainen wrote: > > On Wed, 17 Jan 2001, Tony Gale wrote: > > > >> It looks like this is due to the odd way in which ipchains handles > >> fragments. Try: > >> > >> echo 1 > /proc/sys/net/ipv4/ip_always_defrag > > > > Thanks, this seems to do the trick. Does this oddity still exist > > in 2.4? > > > > Well, I haven't found it, but there is > /proc/sys/net/ipv4/ipfrag_high_thresh > /proc/sys/net/ipv4/ipfrag_low_thresh > /proc/sys/net/ipv4/ipfrag_time > > Perhaps 2.4 always defrags packets by default. Anyone confirm? This > is pretty much needed for any kind of firewall/masquerading system.
Connection tracking always defrags as needed. masquerading/NAT/iptables with connection tracking uses that.
This means that if any of these are enabled and your machine acts as a router lots of CPU could get burned in defragmentation, and packets will not forwarded until all fragments arrived.
All very nasty, but unfortunately there is no alternative.
-Andi - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org Please read the FAQ at http://www.tux.org/lkml/
| |