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To: dev@httpd.apache.org
Subject: how to get httpd to use a proxy, cascading to a 2nd proxy ?
From: "Julian H. Stacey" <jhs@berklix.com>
Organization: http://berklix.com BSD Unix Linux Consultants, Munich Germany
User-agent: EXMH on FreeBSD http://www.berklix.com/free/
Date: Thu, 09 Apr 2015 10:45:59 +0200

Hi dev@httpd.apache.org,
I got no reply from users@ on 2nd April, with :
 Can httpd _use_ (not just _be_) a proxy, cascading to a 2nd proxy on a gate ?

(Not just the common case of httpd serving as a proxy for down stream clients,
 though I need that too on same httpd,  I already have that part working)

I want to get httpd on an internal host to serve as a proxy to a
USB tethered android (which it is already doing), + to pass requests
over ethernet LAN to a 2nd proxy on a LAN gateway. 

This may seem unusual; the reason:
	An android is tethered (IP over USB) to a FreeBSD PC laptop,
	Orweb browser on Android allows use of a proxy, FreeBSD
	laptop runs apache 2.2.29 httpd (listening on the USB IP)
	with httpd proxy enabled & PC allows android to reach various
	httpd PCs on local LAN of the PC.

	I want to tell the httpd on the PC interfacing the android,
	to pass android requests to a 2nd httpd running as LAN proxy
	on the gateway host, to reach the internet.

Why ? Why dont I just configure the FreeBSD PC to bridge packets
from USB to LAN ethernet, & on to LAN gate ?
  - I've failed to create a bridge, 
    Android rejects "route add default gw 192.168.42.139 dev rndis0" 
	with: Not permitted, (I need to root the device),
    I think the FreeBSD PC side is OK:
  	/etc/rc.conf gateway_enable="YES" + sysctl net.inet.ip.forwarding=1
  - Laptop may later get a firewall (to protect LAN from android apps).

If httpd can not use a remote proxy, maybe I'll try packet diversion
via FreeBSD's ipfw,  but I'm hoping dev@httpd have code that calls a proxy ?

I've read
	http://httpd.apache.org/docs/2.2/urlmapping.html#proxy
& contemplated nasty cludges eg:
	1st httpd on PC connected to android:
		<VirtualHost    *>
        	ServerName      play.google.com
		Redirect temp /store/apps http://gate/playgoogle
	2nd httpd on LAN gate:
		Redirect temp /playgoogle http://play.google.com/store/apps
But it would be Ugly & wouldnt work for other URLs, eg when android map apps
go other places to download maps etc.

Maybe there's some clever mapping with
	http://httpd.apache.org/docs/2.2/rewrite/
1st httpd to be receive request
	http://domain/url_under_domain
& emit
	http://gate/indirect_trigger/domain/url_under_domain
& 2nd=gate to redirect to
	http://domain/url_under_domain

Ideas / suggestions / code / URLs please ?

Cheers,
Julian
- --
Julian Stacey, BSD Linux Unix C Sys Eng Consultant Munich http://berklix.com
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