Here are some notes about RADIUS extension to ipppd.
Radius related stuff should be reported to 

   Matjaz Godec <gody@master.slon.net>.

1. Current extensions are based on Lars's radiusclient-0.3-alpha-4. Don't be
scared because of aplha in the name. So before enabling RADIUS features in
configuration please install those.  You can more information at:
http://www.cityline.net/~lf/radius/ and get the libraries at
ftp://ftp.cityline.net/pub/systems/linux/network/radiusclient

2. When compiled ipppd need libradiusclient.so shared library installed in
apropriate library path. If You prefered static libraries put -static in
Makefile.

3. in make config You will find few new options under:
	Options for ipppd  --->
		[ ] Support for RADIUS protocol                         
		[ ] Support for RADIUS wtmp logging           
		"" radiusclient config file path              
		[ ] Support for parsing .TTY file first 

 Support for RADIUS protocol and radiusclient config file path are
mandatory if You want to work with RADIUS server. Config file path is for
unchaged radiuscilent library: /usr/local/lib/radiusclient/radiusclient.conf

RADIUS wtmp logging does also loging into wtmp base, so one can see loged in
users with w and other tools.

 Support for parsing .TTY file first has no meaning in ipppd since parsing
of files with tty suffix is disabled by default.
 

4. How does it work:
 There are two new important options for using radius:
	- radius
	- radacct
 With first (radius) one enables authentication thru RADIUS server.
 With second (radacct) one enables accounting thru RADIUS server. If we
 don't have PAP authentication for this ppp enabled, then user option is
 mandatory for accounting.

 Those options are not interchanged in any way. So only specifying radius
will enable ONLY authentication and not accounting.

 There is also one not so important option:
	- session-limit
 With this option one can limit session time unconditionaly. It is
introduced for the case, where in RADIUS server one specifies session-limit
for specific user.

5. Setup
 There are some important issues when invoking ipppd. One should always
specify IP adresses on command line. If not, static IP assignement via
RADIUS server would not work correctly (remote IP adress will stay unchanged
and next user will get someone elses static IP).
	
 If one uses proxy arp feature and has subnet for ippp connection one shuld
also specify netmask at command line.

6. Notes on accounting
 This version send all basic information needed for RADIUS accounting server
plus:

	- Input-octets
	- Input-packets
	- Output-octets
	- Output-packets
	- Caller-station-id
	- NAS-port-type = ISDN-SYNC

In order to get traffic information one should have kernel compiled with IP
accounting.

When accounting-START record is sent to RADIUS accounting rules for used ippp
interface are inserted into accounting chain.

When accounting-STOP record is to be sent to RADIUS, information from above
mentioned accounting rules are read and accounting rules are deleted from
accounting chain.

So no admin setup is necessary for this setup to work. However there are
some thing to remember. If someone manualy zeroes accounting information IP
traffic between the session measurement won't be acurate. (Unfortunately with
current iimplementation all information in accounting chain is zeroed when
one issues command ipfwadm -A -z). 


Changes:

19980501:

	- radius_start_acct moved to ipcp_up, so we know what remote address
	is. It is no longer fatal if accounting START record is not
	succesfull.  (hint from John Lewis, thanks John).

	- Oh, and in ipcp_up, before we call radius_acct_start, we check if
	we didn't do this before, so no duplicated entries should hapen.

	- Added PW_FRAMED_ADDRESS to START & STOP records

	- Added PW_CALLER_STATION_ID to START RECORD

	- Added PW_NAS_PORT_TYPE to START RECORD

	- Removed radius_init calls in radius.c; they are in options.c now
	  and are called only once, when program is started.

	- If radius or radacct are specified and radius_init fails then pppd
	  dies. It logs cause to SYSLOG before it dies.

	- Question for more knowledgable as me:
		is it ok to reset session timeout in lcp_echo_lowerdown ? 
		does it means, that when we enter this funciton link will go
		down ?  I just saw that idle_timeout is reset in this
		function and I put reseting session timeout also but don't
		know if this is OK ?

	- for ipppd when RADIUS is defined also _linux_=1 is defined, so
	  that we have idle-timeout and session-timeout

	- in main.c char *envtosue is changed to **envtosue, because of
	  warning messages. Whoever put this in, please check that if this
	  is OK.