proxy.conf

# -*- text -*-
##
## proxy.conf -- proxy radius and realm configuration directives
##
##	$Id$

#######################################################################
#
#  Proxy server configuration
#
#  This entry controls the servers behaviour towards ALL other servers
#  to which it sends proxy requests.
#
proxy server {
	#
	#  Note that as of 2.0, the "synchronous", "retry_delay",
	#  "retry_count", and "dead_time" have all been deprecated.
	#  For backwards compatibility, they are are still accepted
	#  by the server, but they ONLY apply to the old-style realm
	#  configuration.  i.e. realms with "authhost" and/or "accthost"
	#  entries.
	#
	#  i.e. "retry_delay" and "retry_count" have been replaced
	#  with per-home-server configuration.  See the "home_server"
	#  example below for details.
	#
	#  i.e. "dead_time" has been replaced with a per-home-server
	#  "revive_interval".  We strongly recommend that this not
	#  be used, however.  The new method is much better.

	#
	#  In 2.0, the server is always "synchronous", and setting
	#  "synchronous = no" is impossible.  This simplifies the
	#  server and increases the stability of the network.
	#  However, it means that the server (i.e. proxy) NEVER
	#  originates packets.  It proxies packets ONLY when it receives
	#  a packet or a re-transmission from the NAS.  If the NAS never
	#  re-transmits, the proxy never re-transmits, either.  This can
	#  affect fail-over, where a packet does *not* fail over to a
	#  second home server.. because the NAS never retransmits the
	#  packet.
	#
	#  If you need to set "synchronous = no", please send a
	#  message to the list <freeradius-users@lists.freeradius.org>
	#  explaining why this feature is vital for your network.

	#
	#  If a realm exists, but there are no live home servers for
	#  it, we can fall back to using the "DEFAULT" realm.  This is
	#  most useful for accounting, where the server can proxy
	#  accounting requests to home servers, but if they're down,
	#  use a DEFAULT realm that is LOCAL (i.e. accthost = LOCAL),
	#  and then store the packets in the "detail" file.  That data
	#  can be later proxied to the home servers by radrelay, when
	#  those home servers come back up again.	

	#  Setting this to "yes" may have issues for authentication.
	#  i.e. If you are proxying for two different ISP's, and then
	#  act as a general dial-up for Gric.  If one of the first two
	#  ISP's has their RADIUS server go down, you do NOT want to
	#  proxy those requests to GRIC.  Instead, you probably want
	#  to just drop the requests on the floor.  In that case, set
	#  this value to 'no'.
	#
	#  allowed values: {yes, no}
	#
	default_fallback = no

}

#######################################################################
#
#  Configuration for the proxy realms.
#
#  As of 2.0. the old-style "realms" file is deprecated, and is not
#  used by FreeRADIUS.
#
#  As of 2.0, the "realm" configuration has changed.  Instead of
#  specifying "authhost" and "accthost" in a realm section, the home
#  servers are specified seperately in a "home_server" section.  For
#  backwards compatibility, you can still use the "authhost" and
#  "accthost" directives.  If you only have one home server for a
#  realm, it is easier to use the old-style configuration.
#
#  However, if you have multiple servers for a realm, we STRONGLY
#  suggest moving to the new-style configuration.
#
#
#  Load-balancing and failover between home servers is handled via
#  a "home_server_pool" section.
#
#  Finally, The "realm" section defines the realm, some options, and
#  indicates which server pool should be used for the realm.
#
#  This change means that simple configurations now require multiple
#  sections to define a realm.  However, complex configurations
#  are much simpler than before, as multiple realms can share the same
#  server pool.
#
#  That is, realms point to server pools, and server pools point to
#  home servers.  Multiple realms can point to one server pool.  One
#  server pool can point to multiple home servers.  Each home server
#  can appear in one or more pools.
#

######################################################################
#
#  This section defines a "Home Server" which is another RADIUS
#  server that gets sent proxied requests.  In earlier versions
#  of FreeRADIUS, home servers were defined in "realm" sections,
#  which was awkward.  In 2.0, they have been made independent
#  from realms, which is better for a number of reasons.
#
home_server localhost {
	#
	#  Home servers can be sent Access-Request packets
	#  or Accounting-Request packets.
	#
	#  Allowed values are:
	#	auth	  - Handles Access-Request packets
	#	acct	  - Handles Accounting-Request packets
	#	auth+acct - Handles Access-Request packets at "port",
	#		    and Accounting-Request packets at "port + 1"
	#	coa	  - Handles CoA-Request and Disconnect-Request packets.
	#		    See also raddb/sites-available/originate-coa
	type = auth

	#
	#  Configure ONE OF the following entries:
	#
	#	IPv4 address
	#
	ipaddr = 127.0.0.1

	#	OR IPv6 address
	# ipv6addr = ::1

	#	OR virtual server	
	# virtual_server = foo

	#	Note that while both ipaddr and ipv6addr will accept
	#	both addresses and host names, we do NOT recommend
	#	using host names.  When you specify a host name, the
	#	server has to do a DNS lookup to find the IP address
	#	of the home server.  If the DNS server is slow or
	#	unresponsive, it means that FreeRADIUS will NOT be
	#	able to determine the address, and will therefore NOT
	#	start.
	#
	#	Also, the mapping of host name to address is done ONCE
	#	when the server starts.  If DNS is later updated to
	#	change the address, FreeRADIUS will NOT discover that
	#	until after a re-start, or a HUP.
	#
	#	If you specify a virtual_server here, then requests
	#	will be proxied internally to that virtual server.
	#	These requests CANNOT be proxied again, however.  The
	#	intent is to have the local server handle packets
	#	when all home servers are dead.
	#
	#	Requests proxied to a virtual server will be passed
	#	through the pre-proxy and post-proxy sections, just
	#	like any other request.  See also the sample "realm"
	#	configuration, below.
	#
	#	None of the rest of the home_server configuration is used
	#	for the "virtual_server" configuration.

	#
	#  The port to which packets are sent.
	#
	#  Usually 1812 for type "auth", and  1813 for type "acct".
	#  Older servers may use 1645 and 1646.
	#  Use 3799 for type "coa"
	#
	port = 1812

	#
	#  The transport protocol.
	#
	#  If unspecified, defaults to "udp", which is the traditional
	#  RADIUS transport.  It may also be "tcp", in which case TCP
	#  will be used to talk to this home server.
	#
	#  When home servers are put into pools, the pool can contain
	#  home servers with both UDP and TCP transports.
	#
	#proto = udp

	#
	#  The shared secret use to "encrypt" and "sign" packets between
	#  FreeRADIUS and the home server.
	#
	#  The secret can be any string, up to 8k characters in length.
	#
	#  Control codes can be entered vi octal encoding,
	#	e.g. "\101\102" == "AB"
	#  Quotation marks can be entered by escaping them,
	#	e.g. "foo\"bar"
	#  Spaces or other "special" characters can be entered
	#  by putting quotes around the string.
	#	e.g. "foo bar"
	#	     "foo;bar"
	#
	secret = testing123

	############################################################
	#
	#  The rest of the configuration items listed here are optional,
	#  and do not have to appear in every home server definition.
	#
	############################################################

	#
	#  You can optionally specify the source IP address used when
	#  proxying requests to this home server.  When the src_ipaddr
	#  it set, the server will automatically create a proxy
	#  listener for that IP address.
	#
	#  If you specify this field for one home server, you will
	#  likely need to specify it for ALL home servers.
	#
	#  If you don't care about the source IP address, leave this
	#  entry commented.
	#
#	src_ipaddr = 127.0.0.1

	#  RFC 5080 suggests that all clients SHOULD include it in an
	#  Access-Request.  The configuration item below tells the
	#  proxying server (i.e. this one) whether or not the home
	#  server requires a Message-Authenticator attribute.  If it
	#  is required (value set to "yes"), then all Access-Request
	#  packets sent to that home server will have a
	#  Message-Authenticator attribute.
	#
	#  We STRONGLY recommend that this flag be set to "yes"
	#  for ALL home servers.  Doing so will have no performance
	#  impact on the proxy or on the home servers.  It will,
	#  however, allow administrators to detect problems earlier.
	#
	#  allowed values: yes, no
	require_message_authenticator = yes

	#
	#  If the home server does not respond to a request within
	#  this time, this server will initiate "zombie_period".
	#
	#  The response window is large because responses MAY be slow,
	#  especially when proxying across the Internet.
	#
	#  Useful range of values: 5 to 60
	response_window = 20

	#
	#  If you want the old behavior of the server rejecting
	#  proxied requests after "response_window" timeout, set
	#  the following configuration item to "yes".
	#
	#  This configuration WILL be removed in a future release
	#  If you believe you need it, email the freeradius-users
	#  list, and explain why it should stay in the server.
	#
#	no_response_fail = no

	#
	#  If the home server does not respond to ANY packets during
	#  the "zombie period", it will be considered to be dead.
	#
	#  A home server that is marked "zombie" will be used for
	#  proxying as a low priority.  If there are live servers,
	#  they will always be preferred to a zombie.  Requests will
	#  be proxied to a zombie server ONLY when there are no
	#  live servers.
	#
	#  Any request that is proxied to a home server will continue
	#  to be sent to that home server until the home server is
	#  marked dead.  At that point, it will fail over to another
	#  server, if a live server is available.  If none is available,
	#  then the "post-proxy-type fail" handler will be called.
	#
	#  If "status_check" below is something other than "none", then
	#  the server will start sending status checks at the start of
	#  the zombie period.  It will continue sending status checks
	#  until the home server is marked "alive".
	#
	#  Useful range of values: 20 to 120
	zombie_period = 40

	############################################################
	#
	#  As of 2.0, FreeRADIUS supports RADIUS layer "status
	#  checks".  These are used by a proxy server to see if a home
	#  server is alive.
	#
	#  These status packets are sent ONLY if the proxying server
	#  believes that the home server is dead.  They are NOT sent
	#  if the proxying server believes that the home server is
	#  alive.  They are NOT sent if the proxying server is not
	#  proxying packets.
	#
	#  If the home server responds to the status check packet,
	#  then it is marked alive again, and is returned to use.
	#
	############################################################

	#
	#  Some home servers do not support status checks via the
	#  Status-Server packet.  Others may not have a "test" user
	#  configured that can be used to query the server, to see if
	#  it is alive.  For those servers, we have NO WAY of knowing
	#  when it becomes alive again.  Therefore, after the server
	#  has been marked dead, we wait a period of time, and mark
	#  it alive again, in the hope that it has come back to
	#  life.
	#
	#  If it has NOT come back to life, then FreeRADIUS will wait
	#  for "zombie_period" before marking it dead again.  During
	#  the "zombie_period", ALL AUTHENTICATIONS WILL FAIL, because
	#  the home server is still dead.  There is NOTHING that can
	#  be done about this, other than to enable the status checks,
	#  as documented below.
	#
	#  e.g. if "zombie_period" is 40 seconds, and "revive_interval"
	#  is 300 seconds, the for 40 seconds out of every 340, or about
	#  10% of the time, all authentications will fail.
	#
	#  If the "zombie_period" and "revive_interval" configurations
	#  are set smaller, than it is possible for up to 50% of
	#  authentications to fail.
	#
	#  As a result, we recommend enabling status checks, and
	#  we do NOT recommend using "revive_interval".
	#
	#  The "revive_interval" is used ONLY if the "status_check"
	#  entry below is "none".  Otherwise, it will not be used,
	#  and should be deleted.
	#
	#  Useful range of values: 60 to 3600
	revive_interval = 120

	#
	#  The proxying server (i.e. this one) can do periodic status
	#  checks to see if a dead home server has come back alive.
	#
	#  If set to "none", then the other configuration items listed
	#  below are not used, and the "revive_interval" time is used
	#  instead.
	#
	#  If set to "status-server", the Status-Server packets are
	#  sent.  Many RADIUS servers support Status-Server.  If a
	#  server does not support it, please contact the server
	#  vendor and request that they add it.
	#
	#  If set to "request", then Access-Request, or Accounting-Request
	#  packets are sent, depending on the "type" entry above (auth/acct).
	#  
	#  Allowed values: none, status-server, request
	status_check = status-server

	#
	#  If the home server does not support Status-Server packets,
	#  then the server can still send Access-Request or
	#  Accounting-Request packets, with a pre-defined user name.
	#
	#  This practice is NOT recommended, as it may potentially let
	#  users gain network access by using these "test" accounts!
	#
	#  If it is used, we recommend that the home server ALWAYS
	#  respond to these Access-Request status checks with
	#  Access-Reject.  The status check just needs an answer, it
	#  does not need an Access-Accept.
	#
	#  For Accounting-Request status checks, only the username
	#  needs to be set.  The rest of the accounting attribute are
	#  set to default values.  The home server that receives these
	#  accounting packets SHOULD NOT treat them like normal user
	#  accounting packets.  i.e It should probably NOT log them to
	#  a database.
	#
	# username = "test_user_please_reject_me"
	# password = "this is really secret"

	#
	#  Configure the interval between sending status check packets.
	#
	#  Setting it too low increases the probability of spurious
	#  fail-over and fallback attempts.
	#
	#  Useful range of values: 6 to 120
	check_interval = 30

	#
	#  Configure the number of status checks in a row that the
	#  home server needs to respond to before it is marked alive.
	#
	#  If you want to mark a home server as alive after a short
	#  time period of being responsive, it is best to use a small
	#  "check_interval", and a large value for
	#  "num_answers_to_alive".  Using a long "check_interval" and
	#  a small number for "num_answers_to_alive" increases the
	#  probability of spurious fail-over and fallback attempts.
	#
	#  Useful range of values: 3 to 10
	num_answers_to_alive = 3

	#
	#  Limit the total number of outstanding packets to the home
	#  server.
	#
	#  if ((#request sent) - (#requests received)) > max_outstanding
	#	then stop sending more packets to the home server
	#
	#  This lets us gracefully fall over when the home server
	#  is overloaded.
	max_outstanding = 65536

	#
	#  The configuration items in the next sub-section are used ONLY
	#  when "type = coa".  It is ignored for all other type of home
	#  servers.
	#
	#  See RFC 5080 for the definitions of the following terms.
	#  RAND is a function (internal to FreeRADIUS) returning
	#  random numbers between -0.1 and +0.1
	#
	#  First Re-transmit occurs after:
	#
	#	 RT = IRT + RAND*IRT
	#
	#  Subsequent Re-transmits occur after:
	#
	#	RT = 2 * RTprev + RAND * RTprev
	#
	#  Re-trasnmits are capped at:
	#
	#	if (MRT && (RT > MRT)) RT = MRT + RAND * MRT
	#
	#  For a maximum number of attempts: MRC
	#
	#  For a maximum (total) period of time: MRD.
	#
	coa {
		# Initial retransmit interval: 1..5
		irt = 2

		# Maximum Retransmit Timeout: 1..30 (0 == no maximum)
		mrt = 16

		# Maximum Retransmit Count: 1..20 (0 == retransmit forever)
		mrc = 5

		# Maximum Retransmit Duration: 5..60
		mrd = 30
	}

	#
	#  Connection limiting for home servers with "proto = tcp".
	#
	#  This section is ignored for other home servers.
	#
	limit {
	      #
	      #  Limit the number of TCP connections to the home server.
	      #
	      #  The default is 16.
	      #  Setting this to 0 means "no limit"
	      max_connections = 16

	      #
	      #  Limit the total number of requests sent over one
	      #  TCP connection.  After this number of requests, the
	      #  connection will be closed.  Any new packets that are
	      #  proxied to the home server will result in a new TCP
	      #  connection being made.
	      #
	      #  Setting this to 0 means "no limit"
	      max_requests = 0

	      #
	      #  The lifetime, in seconds, of a TCP connection.  After
	      #  this lifetime, the connection will be closed.
	      #
	      #  Setting this to 0 means "forever".
	      lifetime = 0

	      #
	      #  The idle timeout, in seconds, of a TCP connection.
	      #  If no packets have been sent over the connection for
	      #  this time, the connection will be closed.
	      #
	      #  Setting this to 0 means "no timeout".
	      idle_timeout = 0
	}

}

# Sample virtual home server.
# 
#
#home_server virtual.example.com {
#	    virtual_server = virtual.example.com
#}

######################################################################
#
#  This section defines a pool of home servers that is used
#  for fail-over and load-balancing.  In earlier versions of
#  FreeRADIUS, fail-over and load-balancing were defined per-realm.
#  As a result, if a server had 5 home servers, each of which served
#  the same 10 realms, you would need 50 "realm" entries.
#
#  In version 2.0, you would need 5 "home_server" sections,
#  10 'realm" sections, and one "home_server_pool" section to tie the
#  two together.
#
home_server_pool my_auth_failover {
	#
	#  The type of this pool controls how home servers are chosen.
	#
	#  fail-over - the request is sent to the first live
	#  	home server in the list.  i.e. If the first home server
	#	is marked "dead", the second one is chosen, etc.
	#
	#  load-balance - the least busy home server is chosen,
	#	where "least busy" is counted by taking the number of
	#	requests sent to that home server, and subtracting the
	#	number of responses received from that home server.
	#
	#	If there are two or more servers with the same low
	#	load, then one of those servers is chosen at random.
	#	This configuration is most similar to the old
	#	"round-robin" method, though it is not exactly the same.
	#
	#	Note that load balancing does not work well with EAP,
	#	as EAP requires packets for an EAP conversation to be
	#	sent to the same home server.  The load balancing method
	#	does not keep state in between packets, meaning that
	#	EAP packets for the same conversation may be sent to
	#	different home servers.  This will prevent EAP from
	#	working.
	#
	#	For non-EAP authentication methods, and for accounting
	#	packets, we recommend using "load-balance".  It will
	#	ensure the highest availability for your network.
	#
	#  client-balance - the home server is chosen by hashing the
	#	source IP address of the packet.  If that home server
	#	is down, the next one in the list is used, just as
	#	with "fail-over".
	#
	#	There is no way of predicting which source IP will map
	#	to which home server.
	#
	#	This configuration is most useful to do simple load
	#	balancing for EAP sessions, as the EAP session will
	#	always be sent to the same home server.
	#
	#  client-port-balance - the home server is chosen by hashing
	#	the source IP address and source port of the packet.
	#	If that home server is down, the next one in the list
	#	is used, just as with "fail-over".
	#
	#	This method provides slightly better load balancing
	#	for EAP sessions than "client-balance".  However, it
	#	also means that authentication and accounting packets
	#	for the same session MAY go to different home servers.
	#
	#  keyed-balance - the home server is chosen by hashing (FNV)
	#	the contents of the Load-Balance-Key attribute from the
	#	control items.  The  request is then sent to home server
	#	chosen by taking:
	#
	#		server = (hash % num_servers_in_pool).
	#
	#	If there is no Load-Balance-Key in the control items,
	#	the load balancing method is identical to "load-balance".
	#
	#	For most non-EAP authentication methods, The User-Name
	#	attribute provides a good key.  An "unlang" policy can
	#	be used to copy the User-Name to the Load-Balance-Key
	#	attribute.  This method may not work for EAP sessions,
	#	as the User-Name outside of the TLS tunnel is often
	#	static, e.g. "anonymous@realm".
	#
	#
	#  The default type is fail-over.
	type = fail-over

	#
	#  A virtual_server may be specified here.  If so, the
	#  "pre-proxy" and "post-proxy" sections are called when
	#  the request is proxied, and when a response is received.
	#
	#  This lets you have one policy for all requests that are proxied
	#  to a home server.  This policy is completely independent of
	#  any policies used to receive, or process the request.
	#
	#virtual_server = pre_post_proxy_for_pool

	#
	#  Next, a list of one or more home servers.  The names
	#  of the home servers are NOT the hostnames, but the names
	#  of the sections.  (e.g. home_server foo {...} has name "foo".
	#
	#  Note that ALL home servers listed here have to be of the same
	#  type.  i.e. they all have to be "auth", or they all have to
	#  be "acct", or the all have to be "auth+acct".
	#
	home_server = localhost

	#  Additional home servers can be listed.
	#  There is NO LIMIT to the number of home servers that can
	#  be listed, though using more than 10 or so will become
	#  difficult to manage.
	#
	# home_server = foo.example.com
	# home_server = bar.example.com
	# home_server = baz.example.com
	# home_server = ...


	#
	#  If ALL home servers are dead, then this "fallback" home server
	#  is used.  If set, it takes precedence over any realm-based
	#  fallback, such as the DEFAULT realm.
	#
	#  For reasons of stability, this home server SHOULD be a virtual
	#  server.  Otherwise, the fallback may itself be dead!
	#
	#fallback = virtual.example.com
}

######################################################################
#
#
#  This section defines a new-style "realm".  Note the in version 2.0,
#  there are many fewer configuration items than in 1.x for a realm.
#
#  Automatic proxying is done via the "realms" module (see "man
#  rlm_realm").  To manually proxy the request put this entry in the
#  "users" file:

#
#
#DEFAULT	Proxy-To-Realm := "realm_name"
#
#
realm example.com {
	#
	#  Realms point to pools of home servers.
#
	#  For authentication, the "auth_pool" configuration item
	#  should point to a "home_server_pool" that was previously
	#  defined.  All of the home servers in the "auth_pool" must
	#  be of type "auth".
	#
	#  For accounting, the "acct_pool" configuration item
	#  should point to a "home_server_pool" that was previously
	#  defined.  All of the home servers in the "acct_pool" must
	#  be of type "acct".
	#
	#  If you have a "home_server_pool" where all of the home servers
	#  are of type "auth+acct", you can just use the "pool"
	#  configuration item, instead of specifying both "auth_pool"
	#  and "acct_pool".

	auth_pool = my_auth_failover
#	acct_pool = acct

	#
	#  Normally, when an incoming User-Name is matched against the
	#  realm, the realm name is "stripped" off, and the "stripped"
	#  user name is used to perform matches.
	#
	#  e.g. User-Name = "bob@example.com" will result in two new
	#  attributes being created by the "realms" module:
	#
	#	Stripped-User-Name = "bob"
	#	Realm = "example.com"
	#
	#  The Stripped-User-Name is then used as a key in the "users"
	#  file, for example.
	#
	#  If you do not want this to happen, uncomment "nostrip" below.
	#
	# nostrip

	#  There are no more configuration entries for a realm.
}


#
#  This is a sample entry for iPass.
#  Note that you have to define "ipass_auth_pool" and
#  "ipass_acct_pool", along with home_servers for them, too.
#
#realm IPASS {
#	nostrip
#
#	auth_pool = ipass_auth_pool
#	acct_pool = ipass_acct_pool
#}

#
#  This realm is used mainly to cancel proxying.  You can have
#  the "realm suffix" module configured to proxy all requests for
#  a realm, and then later cancel the proxying, based on other
#  configuration.
#
#  For example, you want to terminate PEAP or EAP-TTLS locally,
#  you can add the following to the "users" file:
#
#  DEFAULT EAP-Type == PEAP, Proxy-To-Realm := LOCAL
#
realm LOCAL {
	#  If we do not specify a server pool, the realm is LOCAL, and
	#  requests are not proxied to it.
}

#
#  This realm is for requests which don't have an explicit realm
#  prefix or suffix.  User names like "bob" will match this one.
#
#realm NULL {
#	authhost	= radius.company.com:1600
#	accthost	= radius.company.com:1601
#	secret		= testing123
#}

#
#  This realm is for ALL OTHER requests.
#
#realm DEFAULT {
#	authhost	= radius.company.com:1600
#	accthost	= radius.company.com:1601
#	secret		= testing123
#}


#  This realm "proxies" requests internally to a virtual server.
#  The pre-proxy and post-proxy sections are run just as with any
#  other kind of home server.  The virtual server then receives
#  the request, and replies, just as with any other packet.
#
#  Once proxied internally like this, the request CANNOT be proxied
#  internally or externally.
#
#realm virtual.example.com {
#	virtual_server = virtual.example.com
#}
#

#
#  Regular expressions may also be used as realm names.  If these are used,
#  then the "find matching realm" process is as follows:
#
#    1) Look for a non-regex realm with an *exact* match for the name.
#       If found, it is used in preference to any regex matching realm.
#
#    2) Look for a regex realm, in the order that they are listed
#       in the configuration files.  Any regex match is performed in
#	a case-insensitive fashion.
#
#    3) If no realm is found, return the DEFAULT realm, if any.
#
#  The order of the realms matters in step (2).  For example, defining
#  two realms ".*\.example.net$" and ".*\.test\.example\.net$" will result in
#  the second realm NEVER matching.  This is because all of the realms
#  which match the second regex also match the first one.  Since the
#  first regex matches, it is returned.
#
#  The solution is to list the realms in the opposite order,. e.g.
#  ".*\.test\.example.net$", followed by ".*\.example\.net$".
#
#
#  Some helpful rules:
#
#   - always place a '~' character at the start of the realm name.
#     This signifies that it is a regex match, and not an exact match
#     for the realm.
#
#   - place the regex in double quotes.  This helps the configuration
#     file parser ignore any "special" characters in the regex.
#     Yes, this rule is different than the normal "unlang" rules for
#     regular expressions.  That may be fixed in a future release.
#
#   - use two back-slashes '\\' whenever you need one backslash in the
#     regex.  e.g. "~.*\\.example\\.net$", and not "~\.example\.net$".
#     This is because the regex is in a double-quoted string, and normal
#     rules apply for double-quoted strings.
#
#   - If you are matching domain names, use two backslashes in front of
#     every '.' (dot or period).  This is because '.' has special meaning
#     in a regular expression: match any character.  If you do not do this,
#     then "~.*.example.net$" will match "fooXexampleYnet", which is likely
#     not what you want
#
#   - If you are matching domain names, put a '$' at the end of the regex
#     that matches the domain name.  This tells the regex matching code
#     that the realm ENDS with the domain name, so it does not match
#     realms with the domain name in the middle.  e.g. "~.*\\.example\\.net"
#     will match "test.example.netFOO", which is likely not what you want.
#     Using "~(.*\\.)example\\.net$" is better.
#
#  The more regex realms that are defined, the more time it takes to
#  process them.  You should define as few regex realms as possible
#  in order to maximize server performance.
#
#realm "~(.*\\.)*example\\.net$" {
#      auth_pool = my_auth_failover
#}