lkml.org 
[lkml]   [2004]   [Aug]   [22]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRE: Cursed Checksums
From
Date
On Sun, 2004-08-22 at 18:38, Josan Kadett wrote:
> In normal conditions, when NAT translates an IP header, it should do correct
> checksumming. However; when the source IP address of a packet is
> manipulated, Iptables still seems to use the "original" IP address and
> calculate the checksum accordingly. This way even if I use 3 three boxes;
>
> Original Packet --> NAT 1 --> NAT 2 --> NAT3 --> Still incorrect checksum

Sure. That's why I think this is a job for ebtables.
Note: EBtables, not IPtables. This is lower level,
dealing with raw Ethernet packets. It should be able
to mangle anything in the packet.

Just as iptables lets you change any 32-bit value in
an IP packet, ebtables should let you change any 32-bit
value in an Ethernet packet. Unlike iptables, it could
operate prior to the IP checksum verification.

Sadly, it looks like u32 mangle rules are missing.


-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2005-03-22 14:05    [W:0.033 / U:0.076 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site