Alter TCP packet not work fine with netfilter hook

Alter TCP packet not work fine with netfilter hook

[nt pm]

Hi netfilter family,
I'm a newbie to netfilter.
I have just developt a crypto module using netfilter hook.
In this module :
SENDER : IP payload will be encrypted at POST ROUTING hook
RECEIVE : IP payload wil be decrypted at PRE ROUTING hook.

The module work fine with ICMP & UDP but it NOT work fine with TCP: 2
machine still receive packet at hook but application not communicate
together.

I don't know whether any mystery in netfilter or linux network kernel at here?

Thanks :)

Re: Alter TCP packet not work fine with netfilter hook

[Jan Engelhardt]

On Tuesday 2012-01-31 05:50, nt pm wrote:

>Hi netfilter family,
>I'm a newbie to netfilter.
>I have just developt a crypto module using netfilter hook.
>In this module :
>SENDER : IP payload will be encrypted at POST ROUTING hook
>RECEIVE : IP payload wil be decrypted at PRE ROUTING hook.
>
>The module work fine with ICMP & UDP but it NOT work fine with TCP: 2
>machine still receive packet at hook but application not communicate
>together.
>
>I don't know whether any mystery in netfilter or linux network kernel at here?

And what makes you think we would know what happens in your hidden code?

Re: Alter TCP packet not work fine with netfilter hook

[Jan Engelhardt]

On Tuesday 2012-01-31 05:46, Cao Xuan Sang wrote:

>> Hi netfilter family,
>> I'm a newbie to netfilter.
>> I have just developt a crypto module using netfilter hook.
>> In this module :
>> SENDER : IP payload will be encrypted at POST ROUTING hook
>> RECEIVE : IP payload wil be decrypted at PRE ROUTING hook.
>>
>> The module work fine with ICMP & UDP but it NOT work fine with TCP: 2 machine still receive packet at hook but application not communicate together.
>>
>> I don't know whether any mystery in netfilter or linux network kernel at here?
>>
>> Thanks :)
>--
>To unsubscribe from this list: send the line "unsubscribe netfilter-devel" in

I just wonder what's up with people that hit reply and send without 
writing anything (or even adding to cc).

Re: Alter TCP packet not work fine with netfilter hook

[Cao Xuan Sang]

> Hi netfilter family,
> I'm a newbie to netfilter.
> I have just developt a crypto module using netfilter hook.
> In this module :
> SENDER : IP payload will be encrypted at POST ROUTING hook
> RECEIVE : IP payload wil be decrypted at PRE ROUTING hook.
>
> The module work fine with ICMP & UDP but it NOT work fine with TCP: 2 machine still receive packet at hook but application not communicate together.
>
> I don't know whether any mystery in netfilter or linux network kernel at here?
>
> Thanks :)