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From Puneet Mohan <>
Subject Re: Apache : IPv4 mapped address Issue
Date Tue, 01 Mar 2011 14:22:00 GMT
Hi Jeho,

I applied the patch available at ""
given by Nicolas Normand.

Well, after researching (or I should say playing) a bit in with apache
source code, I can say that proxy server could bind to the non-local IPv4
mapped address as long as the socket is AF_INET6.

The problem I am facing over here is, Apache is able to bind to an ipv6
socket and accepts ipv4 connections on it.
   addr.sin6_family = AF_INET6;
   addr.sin6_port = htons(portnum);
   inet_pton(AF_INET6, "0::0", &addr.sin6_addr)
   bind(sd, (struct sockaddr*)&addr, sizeof(addr)) != 0 )
   listen(sd, 15) != 0 )
Due to this, web traffic coming from the IPv4 client is converted to the
"IPv4 mapped address" traffic .

So,  when I bind it to the non-local IP prior to connect() to the origin
server the bind couldn't understand the IPv4 mapped address as the other
socket opened for server side is a AF_INET(I requested IPv4 address from the
client) and transparency fails.

Puneet Mohan

This results in IPv4 mapped addresses in the access.log like

On Tue, Mar 1, 2011 at 4:23 PM, JeHo Park <> wrote:

> Hello Puneet Mohan,
> 2011-03-01 오후 6:51, Puneet Mohan 쓴 글:
>> Hi Jeff Trawick,
>> I am presently implementing transparency in Apache source code. So the
>> strange thing I noticed that while binding to a non-local IP prior to
>> connect (), the remote addr(i.e. the client_addr) it binds to is in the IPv4
>> mapped address whereas the socket descriptor created is IPv4 type only.
>>  did you apply tproxy version2 to your apache proxy code ?
> if so, i wonder whether tproxy2 core can support IPv4 mapped IPv6 address
> or not
>  As a result of this I couldn’t able to bind to the non-local IP.
>> The work around I tried is manipulating the bits of IPv4 mapped address,
>> but I don’t feel it to be convincing.
>> Regards,
>> Puneet Mohan

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