examples/transparent_proxy.cfg

#
# This is an example of how to configure HAProxy to be used as a 'full transparent proxy' for a single backend server.
#
# Note that to actually make this work extra firewall/nat rules are required.
# Also HAProxy needs to be compiled with support for this, in HAProxy1.5-dev19 you can check if this is the case with "haproxy -vv".
#

global
frontend MyFrontend
	bind	192.168.1.22:80
	default_backend		TransparentBack_http

backend TransparentBack_http
	mode			http
	source 0.0.0.0 usesrc client
	server			MyWebServer 192.168.0.40:80

#
# To create the the nat rules perform the following:
#
# ### (FreeBSD 8) ###
# --- Step 1 ---
# ipfw is needed to get 'reply traffic' back to the HAProxy process, this can be achieved by configuring a rule like this:
#	fwd localhost tcp from 192.168.0.40 80 to any in recv em0
#
# The following would be even better but this did not seam to work on the pfSense2.1 distribution of FreeBSD 8.3:
#   fwd 127.0.0.1:80 tcp from any 80 to any in recv ${outside_iface} uid ${proxy_uid}
#
# If only 'pf' is currently used some aditional steps are needed to load and configure ipfw:
# You need to configure this to always run on startup:
#
# /sbin/kldload ipfw
# /sbin/sysctl net.inet.ip.pfil.inbound="pf" net.inet6.ip6.pfil.inbound="pf" net.inet.ip.pfil.outbound="pf" net.inet6.ip6.pfil.outbound="pf"
# /sbin/sysctl net.link.ether.ipfw=1
# ipfw add 10 fwd localhost tcp from 192.168.0.40 80 to any in recv em0
#
# the above does the folowing:
# - load the ipfw kernal module
# - set pf as the outer firewall to keep control of routing packets for example to route them to a non-default gateway
# - enable ipfw
# - set a rule to catches reply traffic on em0 comming from the webserver
#
# --- Step 2 ---
# To also make the client connection transparent its possible to redirect incomming requests to HAProxy with a pf rule:
#   rdr on em1 proto tcp from any to 192.168.0.40 port 80 -> 192.168.1.22
# here em1 is the interface that faces the clients, and traffic that is originally send straight to the webserver is redirected to HAProxy
#
# ### (FreeBSD 9) (OpenBSD 4.4) ###
#   pf supports "divert-reply" which is probably better suited for the job above then ipfw..
#