# IPv6 addresses for host name are incorrectly trimmed by nginx **URL:** \ **Category:** NGINX\ **Created:** [November 28, 2010, 8:20pm UTC](https://www.ruby-forum.com/t/ipv6-addresses-for-host-name-are-incorrectly-trimmed-by-nginx/199761 "2010-11-28T20:20:43Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![Dobai-Pataky\_BSSSSl](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/77aa72/32.png) [@Dobai-Pataky\_BSSSSl](https://www.ruby-forum.com/u/Dobai-Pataky_BSSSSl)\ **Post date:** [November 28, 2010, 8:20pm UTC](https://www.ruby-forum.com/t/ipv6-addresses-for-host-name-are-incorrectly-trimmed-by-nginx/199761/1 "2010-11-28T20:20:43Z")
I’m trying to test IPv6 on a couple of sites and I seem to have encountered a bug with nginx. I have 2 backend servers behind a proxy, all servers run nginx 0.8.53. If I enter the IPv6 address into the browser, the address is trimmed when it reaches the backend server. Here is an example using PHP: Direct request to backend server (works): http://[2a02:40:40:7::3]/test.php $\_SERVER[‘HTTP\_HOST’] = [2a02:40:40:7::3] Via proxy: http://[2a02:40:40:7::7]/test.php $\_SERVER[‘HTTP\_HOST’] = [2a02:40:40:7: It appears the last semi colon and number are trimmed off the IPv6 address, for example if I enter the full IPv6 address I get this: http://[2a02:40:40:7:0:0:0:7]/test.php $\_SERVER[‘HTTP\_HOST’] = [2a02:40:40:7:0:0:0 I’ve spent a couple of hours trying different scenarios and added custom logging to log the value of the $host variable and as far as I can tell nginx seems to always incorrectly trim the value of $host for IPv6 addresses. Here is an example log entry, with an incorrectly logged host name: [28/Nov/2010:17:50:08 +0000] [2a02:40:40:7: “GET /test.php HTTP/1.1” The funny thing is that the correct value is always passed to PHP (for direct requests), but the value of $host is always trimmed incorrectly. As the host name is passed to the backend server via a proxy\_set\_header directive the incorrect value is always passed to the backend and therefore incorrectly passed to PHP in this instance. ---
**Author:** ![phoyce](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/p/bc8723/32.png) [@phoyce](https://www.ruby-forum.com/u/phoyce)\ **Post date:** [November 28, 2010, 10:31pm UTC](https://www.ruby-forum.com/t/ipv6-addresses-for-host-name-are-incorrectly-trimmed-by-nginx/199761/2 "2010-11-28T22:31:42Z")
Here is debug output showing the problem: 2010/11/28 21:22:37 [debug] 10417#0: accept on [2a02:40:40:7::7]:80, ready: 0 2010/11/28 21:22:37 [debug] 10417#0: posix\_memalign: 0000000001031DA0:256 @16 2010/11/28 21:22:37 [debug] 10417#0: \*8 accept: 2001:0:5ef5:79fd:3472:2f12:921f:6666 fd:3 2010/11/28 21:22:37 [debug] 10417#0: \*8 event timer add: 3: 60000:1290979417739 2010/11/28 21:22:37 [debug] 10417#0: \*8 epoll add event: fd:3 op:1 ev:80000001 2010/11/28 21:22:37 [debug] 10417#0: \*8 posix\_memalign: 0000000001063DD0:256 @16 2010/11/28 21:22:37 [debug] 10417#0: \*8 malloc: 000000000103FB90:1288 2010/11/28 21:22:37 [debug] 10417#0: \*8 malloc: 00000000010400A0:1024 2010/11/28 21:22:37 [debug] 10417#0: \*8 posix\_memalign: 00000000010404B0:4096 @16 2010/11/28 21:22:37 [debug] 10417#0: \*8 http process request line 2010/11/28 21:22:37 [debug] 10417#0: \*8 recv: fd:3 644 of 1024 2010/11/28 21:22:37 [debug] 10417#0: \*8 http request line: “GET / HTTP/1.1” 2010/11/28 21:22:37 [debug] 10417#0: \*8 http uri: “/” 2010/11/28 21:22:37 [debug] 10417#0: \*8 http args: “” 2010/11/28 21:22:37 [debug] 10417#0: \*8 http exten: “” 2010/11/28 21:22:37 [debug] 10417#0: \*8 http process request header line 2010/11/28 21:22:37 [debug] 10417#0: \*8 http header: “Accept: application/x-ms-application, image/jpeg, application/xaml+xml, image/gif, image/pjpeg, application/x-ms-xbap, application/x-shockwave-flash, application/vnd.ms-excel, application/vnd.ms-powerpoint, application/msword, _/_” 2010/11/28 21:22:37 [debug] 10417#0: \*8 http header: “Accept-Language: en-GB” 2010/11/28 21:22:37 [debug] 10417#0: \*8 http header: “User-Agent: Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 6.1; WOW64; Trident/4.0; SLCC2; .NET CLR 2.0.50727; .NET CLR 3.5.30729; .NET CLR 3.0.30729; Media Center PC 6.0; InfoPath.2; .NET CLR 1.1.4322; OfficeLiveConnector.1.5; OfficeLivePatch.1.3; .NET4.0C; Creative AutoUpdate v1.40.02)” 2010/11/28 21:22:37 [debug] 10417#0: \*8 http header: “Accept-Encoding: gzip, deflate” \*2010/11/28 21:22:37 [debug] 10417#0: _8 http header: “Host: [2a02:40:40:7::7]”_ 2010/11/28 21:22:37 [debug] 10417#0: \*8 http header: “Connection: Keep-Alive” 2010/11/28 21:22:37 [debug] 10417#0: \*8 http header done 2010/11/28 21:22:37 [debug] 10417#0: \*8 event timer del: 3: 1290979417739 2010/11/28 21:22:37 [debug] 10417#0: \*8 generic phase: 0 2010/11/28 21:22:37 [debug] 10417#0: \*8 rewrite phase: 1 2010/11/28 21:22:37 [debug] 10417#0: \*8 test location: “/” 2010/11/28 21:22:37 [debug] 10417#0: \*8 using configuration “/” 2010/11/28 21:22:37 [debug] 10417#0: \*8 http cl:-1 max:1048576 2010/11/28 21:22:37 [debug] 10417#0: \*8 rewrite phase: 3 2010/11/28 21:22:37 [debug] 10417#0: \*8 post rewrite phase: 4 2010/11/28 21:22:37 [debug] 10417#0: \*8 generic phase: 5 2010/11/28 21:22:37 [debug] 10417#0: \*8 generic phase: 6 2010/11/28 21:22:37 [debug] 10417#0: \*8 generic phase: 7 2010/11/28 21:22:37 [debug] 10417#0: \*8 access phase: 8 2010/11/28 21:22:37 [debug] 10417#0: \*8 access phase: 9 2010/11/28 21:22:37 [debug] 10417#0: \*8 post access phase: 10 2010/11/28 21:22:37 [debug] 10417#0: \*8 http init upstream, client timer: 0 2010/11/28 21:22:37 [debug] 10417#0: \*8 epoll add event: fd:3 op:3 ev:80000005 2010/11/28 21:22:37 [debug] 10417#0: \*8 posix\_memalign: 0000000001036860:4096 @16 2010/11/28 21:22:37 [debug] 10417#0: \*8 http script copy: "Host: " \*2010/11/28 21:22:37 [debug] 10417#0: _8 http script var: “[2a02:40:40:7:”_ 2010/11/28 21:22:37 [debug] 10417#0: \*8 http script copy: " 2010/11/28 21:22:37 [debug] 10417#0: \*8 http script copy: "X-Real-IP: " 2010/11/28 21:22:37 [debug] 10417#0: \*8 http script var: “2001:0:5ef5:79fd:3472:2f12:921f:6666” 2010/11/28 21:22:37 [debug] 10417#0: \*8 http script copy: " 2010/11/28 21:22:37 [debug] 10417#0: \*8 http script copy: "X-Forwarded-For: " 2010/11/28 21:22:37 [debug] 10417#0: \*8 http script var: “2001:0:5ef5:79fd:3472:2f12:921f:6666” 2010/11/28 21:22:37 [debug] 10417#0: \*8 http script copy: " 2010/11/28 21:22:37 [debug] 10417#0: \*8 http script copy: "Connection: close ---
**Author:** ![phoyce](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/p/bc8723/32.png) [@phoyce](https://www.ruby-forum.com/u/phoyce)\ **Post date:** [November 29, 2010, 2:16am UTC](https://www.ruby-forum.com/t/ipv6-addresses-for-host-name-are-incorrectly-trimmed-by-nginx/199761/3 "2010-11-29T02:16:52Z")
Hello! On Sun, Nov 28, 2010 at 07:19:17PM +0000, Phil B. wrote: > Direct request to backend server (works): > > http://[2a02:40:40:7::3]/test.php > $\_SERVER[‘HTTP\_HOST’] = [2a02:40:40:7::3] > > Via proxy: > > http://[2a02:40:40:7::7]/test.php > $\_SERVER[‘HTTP\_HOST’] = [2a02:40:40:7: Known issue, ipv6 address literals not supported. > **[IPv6 bug](http://mailman.nginx.org/pipermail/nginx/2010-November/023652.html)** Maxim D. ---
**Author:** ![phoyce](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/p/bc8723/32.png) [@phoyce](https://www.ruby-forum.com/u/phoyce)\ **Post date:** [November 29, 2010, 9:07am UTC](https://www.ruby-forum.com/t/ipv6-addresses-for-host-name-are-incorrectly-trimmed-by-nginx/199761/4 "2010-11-29T09:07:42Z")
On 29 November 2010 01:15, Maxim D. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > > If I enter the IPv6 address into the browser, the address is trimmed when > > Via proxy: > > > > http://[2a02:40:40:7::7]/test.php > > $\_SERVER[‘HTTP\_HOST’] = [2a02:40:40:7: > > Known issue, ipv6 address literals not supported. > > [IPv6 bug](http://nginx.org/pipermail/nginx/2010-November/023652.html) Thanks for the info, will have to hope that someone has time to fix it at some point! Unfortunately the only way to test via a 6to4 tunnel on an IPv4 connection is to use the full IPv6 address.