<s>
Remote	B-Protocol
Authentication	I-Protocol
Dial-In	I-Protocol
User	I-Protocol
Service	I-Protocol
(	O
RADIUS	B-Protocol
)	O
is	O
a	O
networking	O
protocol	O
that	O
provides	O
centralized	O
authentication	O
,	O
authorization	O
,	O
and	O
accounting	O
(	O
AAA	O
)	O
management	O
for	O
users	O
who	O
connect	O
and	O
use	O
a	O
network	O
service	O
.	O
</s>
<s>
RADIUS	B-Protocol
was	O
developed	O
by	O
Livingston	O
Enterprises	O
in	O
1991	O
as	O
an	O
access	O
server	O
authentication	O
and	O
accounting	O
protocol	O
.	O
</s>
<s>
RADIUS	B-Protocol
is	O
a	O
client/server	B-Operating_System
protocol	I-Operating_System
that	O
runs	O
in	O
the	O
application	B-Application
layer	I-Application
,	O
and	O
can	O
use	O
either	O
TCP	B-Protocol
or	O
UDP	B-Protocol
.	O
</s>
<s>
Network	O
access	O
servers	O
,	O
which	O
control	O
access	O
to	O
a	O
network	O
,	O
usually	O
contain	O
a	O
RADIUS	B-Protocol
client	O
component	O
that	O
communicates	O
with	O
the	O
RADIUS	B-Protocol
server	I-Protocol
.	O
</s>
<s>
RADIUS	B-Protocol
is	O
often	O
the	O
back-end	O
of	O
choice	O
for	O
802.1X	O
authentication	O
.	O
</s>
<s>
A	O
RADIUS	B-Protocol
server	I-Protocol
is	O
usually	O
a	O
background	B-Operating_System
process	I-Operating_System
running	O
on	O
UNIX	B-Application
or	O
Microsoft	B-Application
Windows	I-Application
.	O
</s>
<s>
RADIUS	B-Protocol
is	O
an	O
AAA	O
(	O
authentication	O
,	O
authorization	O
,	O
and	O
accounting	O
)	O
protocol	O
that	O
manages	O
network	O
access	O
.	O
</s>
<s>
RADIUS	B-Protocol
uses	O
two	O
types	O
of	O
packets	B-Protocol
to	O
manage	O
the	O
full	O
AAA	O
process	O
:	O
Access-Request	O
,	O
which	O
manages	O
authentication	O
and	O
authorization	O
;	O
and	O
Accounting-Request	O
,	O
which	O
manages	O
accounting	O
.	O
</s>
<s>
The	O
credentials	O
are	O
passed	O
to	O
the	O
NAS	O
device	O
via	O
the	O
link-layer	B-Protocol
protocol	O
—	O
for	O
example	O
,	O
Point-to-Point	B-Protocol
Protocol	I-Protocol
(	O
PPP	O
)	O
in	O
the	O
case	O
of	O
many	O
dialup	O
or	O
DSL	O
providers	O
or	O
posted	O
in	O
an	O
HTTPS	B-Protocol
secure	O
web	O
form	O
.	O
</s>
<s>
In	O
turn	O
,	O
the	O
NAS	O
sends	O
a	O
RADIUS	B-Protocol
Access	O
Request	O
message	O
to	O
the	O
RADIUS	B-Protocol
server	I-Protocol
,	O
requesting	O
authorization	O
to	O
grant	O
access	O
via	O
the	O
RADIUS	B-Protocol
protocol	O
.	O
</s>
<s>
Additionally	O
,	O
the	O
request	O
may	O
contain	O
other	O
information	O
which	O
the	O
NAS	O
knows	O
about	O
the	O
user	O
,	O
such	O
as	O
its	O
network	B-Protocol
address	I-Protocol
or	O
phone	O
number	O
,	O
and	O
information	O
regarding	O
the	O
user	O
's	O
physical	O
point	O
of	O
attachment	O
to	O
the	O
NAS	O
.	O
</s>
<s>
The	O
RADIUS	B-Protocol
server	I-Protocol
checks	O
that	O
the	O
information	O
is	O
correct	O
using	O
authentication	O
schemes	O
such	O
as	O
PAP	B-Protocol
,	O
CHAP	B-Protocol
or	O
EAP	B-Protocol
.	O
</s>
<s>
The	O
user	O
's	O
proof	O
of	O
identification	O
is	O
verified	O
,	O
along	O
with	O
,	O
optionally	O
,	O
other	O
information	O
related	O
to	O
the	O
request	O
,	O
such	O
as	O
the	O
user	O
's	O
network	B-Protocol
address	I-Protocol
or	O
phone	O
number	O
,	O
account	O
status	O
,	O
and	O
specific	O
network	O
service	O
access	O
privileges	O
.	O
</s>
<s>
Historically	O
,	O
RADIUS	B-Protocol
servers	I-Protocol
checked	O
the	O
user	O
's	O
information	O
against	O
a	O
locally	O
stored	O
flat	O
file	O
database	O
.	O
</s>
<s>
Modern	O
RADIUS	B-Protocol
servers	I-Protocol
can	O
do	O
this	O
,	O
or	O
can	O
refer	O
to	O
external	O
sources	O
—	O
commonly	O
SQL	B-Language
,	O
Kerberos	B-Protocol
,	O
LDAP	B-Protocol
,	O
or	O
Active	B-Protocol
Directory	I-Protocol
servers	O
—	O
to	O
verify	O
the	O
user	O
's	O
credentials	O
.	O
</s>
<s>
The	O
RADIUS	B-Protocol
server	I-Protocol
then	O
returns	O
one	O
of	O
three	O
responses	O
to	O
the	O
NAS	O
:	O
1	O
)	O
Access	O
Reject	O
,	O
2	O
)	O
Access	O
Challenge	O
,	O
or	O
3	O
)	O
Access	O
Accept	O
.	O
</s>
<s>
Access	O
Challenge	O
is	O
also	O
used	O
in	O
more	O
complex	O
authentication	O
dialogs	O
where	O
a	O
secure	O
tunnel	O
is	O
established	O
between	O
the	O
user	O
machine	O
and	O
the	O
Radius	B-Protocol
Server	I-Protocol
in	O
a	O
way	O
that	O
the	O
access	O
credentials	O
are	O
hidden	O
from	O
the	O
NAS	O
.	O
</s>
<s>
Once	O
the	O
user	O
is	O
authenticated	O
,	O
the	O
RADIUS	B-Protocol
server	I-Protocol
will	O
often	O
check	O
that	O
the	O
user	O
is	O
authorized	O
to	O
use	O
the	O
network	O
service	O
requested	O
.	O
</s>
<s>
Again	O
,	O
this	O
information	O
may	O
be	O
stored	O
locally	O
on	O
the	O
RADIUS	B-Protocol
server	I-Protocol
,	O
or	O
may	O
be	O
looked	O
up	O
in	O
an	O
external	O
source	O
such	O
as	O
LDAP	B-Protocol
or	O
Active	B-Protocol
Directory	I-Protocol
.	O
</s>
<s>
Each	O
of	O
these	O
three	O
RADIUS	B-Protocol
responses	O
may	O
include	O
a	O
Reply-Message	O
attribute	O
which	O
may	O
give	O
a	O
reason	O
for	O
the	O
rejection	O
,	O
the	O
prompt	O
for	O
the	O
challenge	O
,	O
or	O
a	O
welcome	O
message	O
for	O
the	O
accept	O
.	O
</s>
<s>
When	O
a	O
client	O
is	O
configured	O
to	O
use	O
RADIUS	B-Protocol
,	O
any	O
user	O
of	O
the	O
client	O
presents	O
authentication	O
information	O
to	O
the	O
client	O
.	O
</s>
<s>
Alternatively	O
,	O
the	O
user	O
might	O
use	O
a	O
link	O
framing	O
protocol	O
such	O
as	O
the	O
Point-to-Point	B-Protocol
Protocol	I-Protocol
(	O
PPP	O
)	O
,	O
which	O
has	O
authentication	O
packets	B-Protocol
which	O
carry	O
this	O
information	O
.	O
</s>
<s>
Once	O
the	O
client	O
has	O
obtained	O
such	O
information	O
,	O
it	O
may	O
choose	O
to	O
authenticate	O
using	O
RADIUS	B-Protocol
.	O
</s>
<s>
When	O
a	O
password	O
is	O
present	O
,	O
it	O
is	O
hidden	O
using	O
a	O
method	O
based	O
on	O
the	O
RSA	O
Message	O
Digest	O
Algorithm	O
MD5	B-Algorithm
.	O
</s>
<s>
When	O
network	O
access	O
is	O
granted	O
to	O
the	O
user	O
by	O
the	O
NAS	O
,	O
an	O
Accounting	O
Start	O
(	O
a	O
RADIUS	B-Protocol
Accounting	O
Request	O
packet	B-Protocol
containing	O
an	O
Acct-Status-Type	O
attribute	O
with	O
the	O
value	O
"	O
start	O
"	O
)	O
is	O
sent	O
by	O
the	O
NAS	O
to	O
the	O
RADIUS	B-Protocol
server	I-Protocol
to	O
signal	O
the	O
start	O
of	O
the	O
user	O
's	O
network	O
access	O
.	O
</s>
<s>
"	O
Start	O
"	O
records	O
typically	O
contain	O
the	O
user	O
's	O
identification	O
,	O
network	B-Protocol
address	I-Protocol
,	O
point	O
of	O
attachment	O
and	O
a	O
unique	O
session	O
identifier	O
.	O
</s>
<s>
Periodically	O
,	O
Interim	O
Update	O
records	O
(	O
a	O
RADIUS	B-Protocol
Accounting	O
Request	O
packet	B-Protocol
containing	O
an	O
Acct-Status-Type	O
attribute	O
with	O
the	O
value	O
"	O
interim-update	O
"	O
)	O
may	O
be	O
sent	O
by	O
the	O
NAS	O
to	O
the	O
RADIUS	B-Protocol
server	I-Protocol
,	O
to	O
update	O
it	O
on	O
the	O
status	O
of	O
an	O
active	O
session	O
.	O
</s>
<s>
Finally	O
,	O
when	O
the	O
user	O
's	O
network	O
access	O
is	O
closed	O
,	O
the	O
NAS	O
issues	O
a	O
final	O
Accounting	O
Stop	O
record	O
(	O
a	O
RADIUS	B-Protocol
Accounting	O
Request	O
packet	B-Protocol
containing	O
an	O
Acct-Status-Type	O
attribute	O
with	O
the	O
value	O
"	O
stop	O
"	O
)	O
to	O
the	O
RADIUS	B-Protocol
server	I-Protocol
,	O
providing	O
information	O
on	O
the	O
final	O
usage	O
in	O
terms	O
of	O
time	O
,	O
packets	B-Protocol
transferred	O
,	O
data	O
transferred	O
,	O
reason	O
for	O
disconnect	O
and	O
other	O
information	O
related	O
to	O
the	O
user	O
's	O
network	O
access	O
.	O
</s>
<s>
Typically	O
,	O
the	O
client	O
sends	O
Accounting-Request	O
packets	B-Protocol
until	O
it	O
receives	O
an	O
Accounting-Response	O
acknowledgement	O
,	O
using	O
some	O
retry	O
interval	O
.	O
</s>
<s>
RADIUS	B-Protocol
is	O
commonly	O
used	O
to	O
facilitate	O
roaming	O
between	O
ISPs	O
,	O
including	O
by	O
:	O
</s>
<s>
RADIUS	B-Protocol
facilitates	O
this	O
by	O
the	O
use	O
of	O
realms	O
,	O
which	O
identify	O
where	O
the	O
RADIUS	B-Protocol
server	I-Protocol
should	O
forward	O
the	O
AAA	O
requests	O
for	O
processing	O
.	O
</s>
<s>
Modern	O
RADIUS	B-Protocol
servers	I-Protocol
allow	O
any	O
character	O
to	O
be	O
used	O
as	O
a	O
realm	O
delimiter	O
,	O
although	O
in	O
practice	O
'	O
@	O
 '	O
and	O
'	O
\	O
 '	O
are	O
usually	O
used	O
.	O
</s>
<s>
When	O
a	O
RADIUS	B-Protocol
server	I-Protocol
receives	O
an	O
AAA	O
request	O
for	O
a	O
user	O
name	O
containing	O
a	O
realm	O
,	O
the	O
server	O
will	O
reference	O
a	O
table	O
of	O
configured	O
realms	O
.	O
</s>
<s>
Proxy	B-Application
Chaining	I-Application
is	O
possible	O
in	O
RADIUS	B-Protocol
and	O
authentication/authorization	O
and	O
accounting	O
packets	B-Protocol
are	O
usually	O
routed	O
between	O
a	O
NAS	O
Device	O
and	O
a	O
Home	O
server	O
through	O
a	O
series	O
of	O
proxies	O
.	O
</s>
<s>
Some	O
of	O
advantages	O
of	O
using	O
proxy	B-Application
chains	I-Application
include	O
scalability	O
improvements	O
,	O
policy	O
implementations	O
and	O
capability	O
adjustments	O
.	O
</s>
<s>
Further	O
,	O
the	O
absence	O
of	O
end	O
to	O
end	O
security	O
in	O
RADIUS	B-Protocol
adds	O
to	O
the	O
criticality	O
of	O
trust	O
among	O
the	O
Proxies	O
involved	O
.	O
</s>
<s>
Proxy	B-Application
Chains	I-Application
are	O
explained	O
in	O
RFC	O
2607	O
.	O
</s>
<s>
Roaming	O
with	O
RADIUS	B-Protocol
exposes	O
the	O
users	O
to	O
various	O
security	O
and	O
privacy	O
concerns	O
.	O
</s>
<s>
More	O
generally	O
,	O
some	O
roaming	O
partners	O
establish	O
a	O
secure	O
tunnel	O
between	O
the	O
RADIUS	B-Protocol
servers	I-Protocol
to	O
ensure	O
that	O
users	O
 '	O
credentials	O
cannot	O
be	O
intercepted	O
while	O
being	O
proxied	O
across	O
the	O
internet	O
.	O
</s>
<s>
This	O
is	O
a	O
concern	O
as	O
the	O
MD5	B-Algorithm
hash	I-Algorithm
built	O
into	O
RADIUS	B-Protocol
is	O
considered	O
insecure	O
.	O
</s>
<s>
RADIUS	B-Protocol
is	O
transported	O
over	O
UDP/IP	B-Protocol
on	O
ports	B-Protocol
1812	O
and	O
1813	O
.	O
</s>
<s>
The	O
RADIUS	B-Protocol
packet	B-Protocol
data	I-Protocol
format	O
is	O
shown	O
to	O
the	O
right	O
.	O
</s>
<s>
Assigned	O
RADIUS	B-Protocol
Codes	O
(	O
decimal	O
)	O
include	O
the	O
following	O
:	O
</s>
<s>
The	O
Length	O
field	O
indicates	O
the	O
length	O
of	O
the	O
entire	O
RADIUS	B-Protocol
packet	B-Protocol
including	O
the	O
Code	O
,	O
Identifier	O
,	O
Length	O
,	O
Authenticator	O
and	O
optional	O
Attribute	O
fields	O
.	O
</s>
<s>
The	O
Authenticator	O
is	O
used	O
to	O
authenticate	O
the	O
reply	O
from	O
the	O
RADIUS	B-Protocol
server	I-Protocol
,	O
and	O
is	O
used	O
in	O
encrypting	O
passwords	O
;	O
its	O
length	O
is	O
16	O
bytes	O
.	O
</s>
<s>
The	O
RADIUS	B-Protocol
Attribute	O
Value	O
Pairs	O
(	O
AVP	O
)	O
carry	O
data	O
in	O
both	O
the	O
request	O
and	O
the	O
response	O
for	O
the	O
authentication	O
,	O
authorization	O
,	O
and	O
accounting	O
transactions	O
.	O
</s>
<s>
The	O
length	O
of	O
the	O
radius	B-Protocol
packet	B-Protocol
is	O
used	O
to	O
determine	O
the	O
end	O
of	O
the	O
AVPs	O
.	O
</s>
<s>
RADIUS	B-Protocol
is	O
extensible	O
;	O
many	O
vendors	O
of	O
RADIUS	B-Protocol
hardware	O
and	O
software	O
implement	O
their	O
own	O
variants	O
using	O
Vendor-Specific	O
Attributes	O
(	O
VSAs	O
)	O
.	O
</s>
<s>
VSA	O
definitions	O
from	O
many	O
other	O
companies	O
remain	O
proprietary	O
and/or	O
ad	O
hoc	O
,	O
nonetheless	O
many	O
VSA	O
dictionaries	O
can	O
be	O
found	O
by	O
downloading	O
the	O
source	O
code	O
of	O
open	O
source	O
RADIUS	B-Protocol
implementations	O
,	O
for	O
example	O
FreeRADIUS	O
.	O
</s>
<s>
The	O
RADIUS	B-Protocol
protocol	O
transmits	O
obfuscated	O
passwords	O
using	O
a	O
shared	O
secret	O
and	O
the	O
MD5	B-Algorithm
hashing	O
algorithm	O
.	O
</s>
<s>
As	O
this	O
particular	O
implementation	O
provides	O
only	O
weak	O
protection	O
of	O
the	O
user	O
's	O
credentials	O
,	O
additional	O
protection	O
,	O
such	O
as	O
IPsec	B-Protocol
tunnels	O
or	O
physically	O
secured	O
data-center	O
networks	O
,	O
should	O
be	O
used	O
to	O
further	O
protect	O
the	O
RADIUS	B-Protocol
traffic	O
between	O
the	O
NAS	O
device	O
and	O
the	O
RADIUS	B-Protocol
server	I-Protocol
.	O
</s>
<s>
Additionally	O
,	O
the	O
user	O
's	O
security	O
credentials	O
are	O
the	O
only	O
part	O
protected	O
by	O
RADIUS	B-Protocol
itself	O
,	O
yet	O
other	O
user-specific	O
attributes	O
such	O
as	O
tunnel-group	O
IDs	O
or	O
VLAN	B-General_Concept
memberships	O
passed	O
over	O
RADIUS	B-Protocol
may	O
be	O
considered	O
sensitive	O
(	O
helpful	O
to	O
an	O
attacker	O
)	O
or	O
private	O
(	O
sufficient	O
to	O
identify	O
the	O
individual	O
client	O
)	O
information	O
as	O
well	O
.	O
</s>
<s>
The	O
RadSec	B-Protocol
protocol	O
claims	O
to	O
solve	O
aforementioned	O
security	O
issues	O
.	O
</s>
<s>
Among	O
the	O
early	O
respondents	O
was	O
Livingston	O
Enterprises	O
and	O
an	O
early	O
version	O
of	O
the	O
RADIUS	B-Protocol
was	O
written	O
after	O
a	O
meeting	O
.	O
</s>
<s>
The	O
early	O
RADIUS	B-Protocol
server	I-Protocol
was	O
installed	O
on	O
a	O
UNIX	B-Application
operating	I-Application
system	I-Application
.	O
</s>
<s>
Livingston	O
Enterprises	O
was	O
acquired	O
by	O
Lucent	O
and	O
together	O
with	O
Merit	O
steps	O
were	O
taken	O
to	O
gain	O
industry	O
acceptance	O
for	O
RADIUS	B-Protocol
as	O
a	O
protocol	O
.	O
</s>
<s>
Both	O
companies	O
offered	O
a	O
RADIUS	B-Protocol
server	I-Protocol
at	O
no	O
charge	O
.	O
</s>
<s>
In	O
1997	O
RADIUS	B-Protocol
was	O
published	O
as	O
RFC	O
2058	O
and	O
RFC	O
2059	O
,	O
current	O
versions	O
are	O
RFC	O
2865	O
and	O
RFC	O
2866	O
.	O
</s>
<s>
The	O
original	O
RADIUS	B-Protocol
standard	O
specified	O
that	O
RADIUS	B-Protocol
is	O
stateless	B-Protocol
and	O
should	O
run	O
over	O
the	O
User	B-Protocol
Datagram	I-Protocol
Protocol	I-Protocol
(	O
UDP	B-Protocol
)	O
.	O
</s>
<s>
For	O
authentication	O
it	O
was	O
envisaged	O
that	O
RADIUS	B-Protocol
should	O
support	O
the	O
Password	B-Protocol
Authentication	I-Protocol
Protocol	I-Protocol
(	O
PAP	B-Protocol
)	O
and	O
the	O
Challenge-Handshake	B-Protocol
Authentication	I-Protocol
Protocol	I-Protocol
(	O
CHAP	B-Protocol
)	O
over	O
the	O
Point-to-Point	B-Protocol
Protocol	I-Protocol
.	O
</s>
<s>
Passwords	O
are	O
hidden	O
by	O
taking	O
the	O
MD5	B-Algorithm
hash	I-Algorithm
of	O
the	O
packet	B-Protocol
and	O
a	O
shared	O
secret	O
,	O
and	O
then	O
XORing	O
that	O
hash	O
with	O
the	O
password	O
.	O
</s>
<s>
The	O
original	O
RADIUS	B-Protocol
also	O
provided	O
more	O
than	O
50	O
attribute-value	O
pairs	O
,	O
with	O
the	O
possibility	O
for	O
vendors	O
to	O
configure	O
their	O
own	O
pairs	O
.	O
</s>
<s>
The	O
choice	O
of	O
the	O
hop-by-hop	O
security	O
model	O
,	O
rather	O
than	O
end-to-end	O
encryption	O
,	O
meant	O
that	O
if	O
several	O
proxy	O
RADIUS	B-Protocol
servers	I-Protocol
are	O
in	O
use	O
,	O
every	O
server	O
must	O
examine	O
,	O
perform	O
logic	O
on	O
and	O
pass	O
on	O
all	O
data	O
in	O
a	O
request	O
.	O
</s>
<s>
RADIUS	B-Protocol
servers	I-Protocol
also	O
did	O
not	O
have	O
the	O
ability	O
to	O
stop	O
access	O
to	O
resources	O
once	O
an	O
authorisation	O
had	O
been	O
issued	O
.	O
</s>
<s>
Subsequent	O
standards	O
such	O
as	O
RFC	O
3576	O
and	O
its	O
successor	O
RFC	O
5176	O
allowed	O
for	O
RADIUS	B-Protocol
servers	I-Protocol
to	O
dynamically	O
change	O
a	O
users	O
authorization	O
,	O
or	O
to	O
disconnect	O
a	O
user	O
entirely	O
.	O
</s>
<s>
Now	O
,	O
several	O
commercial	O
and	O
open-source	O
RADIUS	B-Protocol
servers	I-Protocol
exist	O
.	O
</s>
<s>
Features	O
can	O
vary	O
,	O
but	O
most	O
can	O
look	O
up	O
the	O
users	O
in	O
text	O
files	O
,	O
LDAP	B-Protocol
servers	O
,	O
various	O
databases	O
,	O
etc	O
.	O
</s>
<s>
SNMP	B-Protocol
is	O
often	O
used	O
for	O
remote	O
monitoring	O
and	O
keep-alive	O
checking	O
of	O
a	O
RADIUS	B-Protocol
server	I-Protocol
.	O
</s>
<s>
RADIUS	B-Protocol
proxy	B-Application
servers	I-Application
are	O
used	O
for	O
centralized	O
administration	O
and	O
can	O
rewrite	O
RADIUS	B-Protocol
packets	B-Protocol
on	O
the	O
fly	O
for	O
security	O
reasons	O
,	O
or	O
to	O
convert	O
between	O
vendor	O
dialects	O
.	O
</s>
<s>
The	O
Diameter	B-Protocol
protocol	O
was	O
intended	O
as	O
the	O
replacement	O
for	O
RADIUS	B-Protocol
.	O
</s>
<s>
Diameter	B-Protocol
is	O
largely	O
used	O
in	O
the	O
3G	B-Architecture
space	O
.	O
</s>
<s>
RADIUS	B-Protocol
is	O
used	O
elsewhere	O
.	O
</s>
<s>
One	O
of	O
the	O
largest	O
barriers	O
to	O
having	O
Diameter	B-Protocol
replace	O
RADIUS	B-Protocol
is	O
that	O
switches	B-Protocol
and	O
Access	B-Device
Points	I-Device
typically	O
implement	O
RADIUS	B-Protocol
,	O
but	O
not	O
Diameter	B-Protocol
.	O
</s>
<s>
Diameter	B-Protocol
uses	O
SCTP	B-Protocol
or	O
TCP	B-Protocol
while	O
RADIUS	B-Protocol
typically	O
uses	O
UDP	B-Protocol
as	O
the	O
transport	B-Architecture
layer	I-Architecture
.	O
</s>
<s>
As	O
of	O
2012	O
,	O
RADIUS	B-Protocol
can	O
also	O
use	O
TCP	B-Protocol
as	O
the	O
transport	B-Architecture
layer	I-Architecture
with	O
TLS	B-Protocol
for	O
security	O
.	O
</s>
<s>
The	O
RADIUS	B-Protocol
protocol	O
is	O
currently	O
defined	O
in	O
the	O
following	O
IETF	O
RFC	O
documents	O
.	O
</s>
<s>
RFC	O
Title	O
Date	O
published	O
Related	O
article	O
Related	O
RFCs	O
Note	O
RFC	O
2058	O
Remote	B-Protocol
Authentication	I-Protocol
Dial	I-Protocol
In	I-Protocol
User	I-Protocol
Service	I-Protocol
(	O
RADIUS	B-Protocol
)	O
January	O
1997	O
RADIUS	B-Protocol
Obsoleted	O
by	O
RFC	O
2138	O
RFC	O
2059	O
RADIUS	B-Protocol
Accounting	O
January	O
1997	O
RADIUS	B-Protocol
Obsoleted	O
by	O
RFC	O
2139	O
RFC	O
2138	O
Remote	B-Protocol
Authentication	I-Protocol
Dial	I-Protocol
In	I-Protocol
User	I-Protocol
Service	I-Protocol
(	O
RADIUS	B-Protocol
)	O
April	O
1997	O
RADIUS	B-Protocol
Obsoleted	O
by	O
RFC	O
2865	O
RFC	O
2139	O
RADIUS	B-Protocol
Accounting	O
April	O
1997	O
RADIUS	B-Protocol
Obsoleted	O
by	O
RFC	O
2866	O
RFC	O
2548	O
Microsoft	O
Vendor-specific	O
RADIUS	B-Protocol
Attributes	O
March	O
1999	O
RADIUS	B-Protocol
RFC	O
2607	O
Proxy	B-Application
Chaining	I-Application
and	O
Policy	O
Implementation	O
in	O
Roaming	O
June	O
1999	O
RFC	O
2618	O
RADIUS	B-Protocol
Authentication	O
Client	O
MIB	O
Management	O
information	O
base	O
Obsoleted	O
by	O
RFC	O
4668	O
RFC	O
2619	O
RADIUS	B-Protocol
Authentication	O
Server	O
MIB	O
Management	O
information	O
base	O
Obsoleted	O
by	O
RFC	O
4669	O
RFC	O
2620	O
RADIUS	B-Protocol
Accounting	O
Client	O
MIB	O
June	O
1999	O
Management	O
information	O
base	O
Obsoleted	O
by	O
RFC	O
4670	O
RFC	O
2621	O
RADIUS	B-Protocol
Accounting	O
Server	O
MIB	O
June	O
1999	O
Management	O
information	O
base	O
Obsoleted	O
by	O
RFC	O
4671	O
RFC	O
2809	O
Implementation	O
of	O
L2TP	B-Application
Compulsory	O
Tunneling	O
via	O
RADIUS	B-Protocol
April	O
2000	O
RFC	O
2865	O
Remote	B-Protocol
Authentication	I-Protocol
Dial	I-Protocol
In	I-Protocol
User	I-Protocol
Service	I-Protocol
(	O
RADIUS	B-Protocol
)	O
June	O
2000	O
RADIUS	B-Protocol
Updated	O
by	O
RFC	O
2868	O
,	O
RFC	O
3575	O
,	O
RFC	O
5080	O
This	O
standard	O
describes	O
RADIUS	B-Protocol
authentication	O
and	O
authorization	O
between	O
a	O
Network	O
Access	O
Server	O
(	O
NAS	O
)	O
and	O
a	O
shared	O
RADIUS	B-Protocol
authentication	O
server	O
.	O
</s>
<s>
This	O
protocol	O
is	O
also	O
used	O
to	O
carry	O
configuration	O
information	O
from	O
the	O
RADIUS	B-Protocol
server	I-Protocol
to	O
the	O
NAS	O
.	O
</s>
<s>
RFC	O
2866	O
RADIUS	B-Protocol
Accounting	O
June	O
2000	O
RADIUS	B-Protocol
This	O
standard	O
describes	O
how	O
accounting	O
information	O
is	O
carried	O
from	O
the	O
NAS	O
to	O
a	O
shared	O
RADIUS	B-Protocol
accounting	O
server	O
.	O
</s>
