netdev - Re: incorrect cksum with tcp/udp on lo with 2.6.20/2.6.21/2.6.22

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Mon, 24 Sep 2007 11:44:19 +0200 (CEST)
From:	Krzysztof Oledzki <olel@....pl>
To:	Herbert Xu <herbert@...dor.apana.org.au>
cc:	netdev@...r.kernel.org
Subject: Re: incorrect cksum with tcp/udp on lo with 2.6.20/2.6.21/2.6.22

On Mon, 24 Sep 2007, Herbert Xu wrote:

> On Sun, Sep 23, 2007 at 11:18:58PM +0200, Krzysztof Oledzki wrote:
>>
>> Thank you for the information. Is there any easy way to turn them on? I
>> need it for LVS.
>
> Do you really need it?

Yes. I would like to use a LVS redirector as both a client and a director:
  http://www.austintek.com/LVS/LVS-HOWTO/HOWTO/LVS-HOWTO.LVS-DR.html#director_as_client_in_LVS-DR

> The packets should be checksummed at the point where they physically
> leave the host.

So, with DR mode, packet goes by the lo device (with bad checksum) and 
then get redirected outside. Unfortunately, when it leaves host it has bad 
checksum, too. :(

Best regards,

 				Krzysztof Olędzki