<s>
AICCU	B-Language
(	O
Automatic	O
IPv6	B-Protocol
Connectivity	O
Client	O
Utility	O
)	O
was	O
a	O
popular	O
cross-platform	B-Operating_System
utility	O
for	O
automatically	O
configuring	O
an	O
IPv6	B-Protocol
tunnel	B-Protocol
.	O
</s>
<s>
It	O
is	O
free	B-Application
software	I-Application
available	O
under	O
a	O
BSD	B-Operating_System
license	I-Operating_System
.	O
</s>
<s>
The	O
utility	O
was	O
originally	O
provided	O
for	O
the	O
SixXS	O
Tunnel	B-Protocol
Broker	I-Protocol
but	O
it	O
can	O
also	O
be	O
used	O
by	O
a	O
variety	O
of	O
other	O
tunnel	B-Protocol
brokers	I-Protocol
.	O
</s>
<s>
AICCU	B-Language
was	O
written	O
and	O
maintained	O
by	O
Jeroen	O
Massar	O
.	O
</s>
<s>
AICCU	B-Language
is	O
the	O
successor	O
of	O
the	O
Windows-only	O
and	O
Linux/BSD	O
-variety	O
of	O
the	O
Heartbeat	O
tool	O
that	O
was	O
provided	O
by	O
SixXS	O
,	O
solely	O
to	O
use	O
the	O
Heartbeat	O
protocol	O
.	O
</s>
<s>
When	O
the	O
AYIYA	B-Protocol
protocol	O
came	O
into	O
existence	O
it	O
was	O
decided	O
that	O
to	O
support	O
this	O
new	O
protocol	O
it	O
would	O
be	O
better	O
to	O
merge	O
the	O
Windows	B-Application
and	O
Unix	O
trees	O
into	O
one	O
program	O
and	O
give	O
it	O
a	O
better	O
appearance	O
.	O
</s>
<s>
AICCU	B-Language
has	O
won	O
the	O
Award	O
of	O
Excellence	O
in	O
the	O
Implementation	O
Category	O
of	O
the	O
2004	O
Edition	O
of	O
the	O
IPv6	B-Protocol
Application	O
Contest	O
.	O
</s>
<s>
The	O
following	O
tunneling	B-Protocol
protocols	I-Protocol
are	O
currently	O
supported	O
:	O
</s>
<s>
6in4	B-Protocol
-	O
Standard	O
IPv6	B-Protocol
in	O
IPv4	O
tunnels	O
using	O
protocol	O
41	O
in	O
the	O
IPv4	O
protocol	O
header	O
.	O
</s>
<s>
AYIYA	B-Protocol
-	O
For	O
IPv6	B-Protocol
over	O
IPv4	O
UDP	O
in	O
a	O
secure	O
manner	O
and	O
being	O
able	O
to	O
work	O
through	O
a	O
NAT	O
.	O
</s>
<s>
AICCU	B-Language
primarily	O
uses	O
the	O
TIC	O
protocol	O
to	O
retrieve	O
the	O
configuration	O
parameters	O
of	O
the	O
tunnel	B-Protocol
automatically	O
that	O
the	O
user	O
wants	O
to	O
have	O
configured	O
.	O
</s>
<s>
AICCU	B-Language
finds	O
available	O
tunnel	B-Protocol
brokers	I-Protocol
by	O
looking	O
up	O
the	O
TXT	O
DNS	B-Protocol
records	O
from	O
"	O
_aiccu.sixxs.net	O
"	O
.	O
</s>
<s>
Non-local	O
tunnel	B-Protocol
brokers	I-Protocol
could	O
then	O
be	O
added	O
by	O
requesting	O
the	O
SixXS	O
staff	O
to	O
add	O
an	O
entry	O
to	O
the	O
global	O
DNS	B-Protocol
records	O
.	O
</s>
<s>
The	O
following	O
operating	O
systems/platforms/distributions	O
are	O
supported	O
by	O
AICCU	B-Language
:	O
</s>
<s>
Various	O
distributions	O
have	O
an	O
AICCU	B-Language
package	O
included	O
in	O
their	O
distribution	O
.	O
</s>
<s>
The	O
main	O
usage	O
of	O
AICCU	B-Language
was	O
in	O
combination	O
with	O
the	O
SixXS	O
tunnel	B-Protocol
broker	I-Protocol
service	O
.	O
</s>
<s>
There	O
are	O
other	O
ISPs	O
who	O
have	O
implemented	O
parts	O
of	O
the	O
protocols	O
that	O
AICCU	B-Language
support	O
,	O
for	O
instance	O
the	O
Czech	O
ISP	O
uses	O
AICCU	B-Language
to	O
configure	O
tunnels	O
automatically	O
for	O
their	O
users	O
by	O
providing	O
a	O
TIC	O
(	O
Tunnel	B-Protocol
Information	O
and	O
Control	O
protocol	O
)	O
implementation	O
that	O
ignores	O
the	O
username/password/tunnel_id	O
but	O
uses	O
the	O
source	O
address	O
where	O
the	O
TIC	O
connection	O
originates	O
from	O
to	O
determine	O
and	O
return	O
the	O
tunnel	B-Protocol
configuration	O
using	O
the	O
TIC	O
protocol	O
,	O
which	O
AICCU	B-Language
then	O
uses	O
to	O
configure	O
the	O
tunnel	B-Protocol
.	O
</s>
