<s>
LogMeIn	B-Application
Hamachi	I-Application
is	O
a	O
virtual	B-Application
private	I-Application
network	I-Application
(	O
VPN	B-Application
)	O
application	O
developed	O
and	O
released	O
in	O
2004	O
by	O
Alex	O
Pankratov	O
.	O
</s>
<s>
It	O
is	O
capable	O
of	O
establishing	O
direct	O
links	O
between	O
computers	O
that	O
are	O
behind	O
network	B-Protocol
address	I-Protocol
translation	I-Protocol
(	O
NAT	O
)	O
firewalls	O
without	O
requiring	O
reconfiguration	O
(	O
when	O
the	O
user	O
's	O
PC	O
can	O
be	O
accessed	O
directly	O
without	O
relays	O
from	O
the	O
Internet/WAN	O
side	O
)	O
.	O
</s>
<s>
Like	O
other	O
VPNs	B-Application
,	O
it	O
establishes	O
a	O
connection	O
over	O
the	O
Internet	O
that	O
emulates	O
the	O
connection	O
that	O
would	O
exist	O
if	O
the	O
computers	O
were	O
connected	O
over	O
a	O
local	B-General_Concept
area	I-General_Concept
network	I-General_Concept
(	O
LAN	B-General_Concept
)	O
.	O
</s>
<s>
Hamachi	B-Application
became	O
a	O
LogMeIn	B-Application
product	O
after	O
the	O
acquisition	O
of	O
Applied	O
Networking	O
Inc	O
.	O
in	O
2006	O
.	O
</s>
<s>
It	O
is	O
currently	O
available	O
as	O
a	O
production	O
version	O
for	O
Microsoft	B-Application
Windows	I-Application
and	O
macOS	B-Application
,	O
as	O
a	O
beta	O
version	O
for	O
Linux	B-Application
,	O
and	O
as	O
a	O
system-VPN-based	O
client	O
compatible	O
with	O
Android	B-Application
and	O
iOS	B-Application
.	O
</s>
<s>
For	O
paid	O
subscribers	O
Hamachi	B-Application
runs	O
in	O
the	O
background	O
on	O
idle	O
computers	O
.	O
</s>
<s>
Hamachi	B-Application
is	O
a	O
proprietary	B-Application
centrally-managed	O
VPN	B-Application
system	O
,	O
consisting	O
of	O
the	O
server	O
cluster	O
managed	O
by	O
the	O
vendor	O
of	O
the	O
system	O
and	O
the	O
client	O
software	O
,	O
which	O
is	O
installed	O
on	O
end-user	O
devices	O
.	O
</s>
<s>
Client	O
software	O
adds	O
a	O
virtual	B-General_Concept
network	I-General_Concept
interface	I-General_Concept
to	O
a	O
computer	O
,	O
and	O
it	O
is	O
used	O
for	O
intercepting	O
outbound	O
as	O
well	O
as	O
injecting	O
inbound	O
VPN	B-Application
traffic	O
.	O
</s>
<s>
Outbound	O
traffic	O
sent	O
by	O
the	O
operating	B-General_Concept
system	I-General_Concept
to	O
this	O
interface	O
is	O
delivered	O
to	O
the	O
client	O
software	O
,	O
which	O
encrypts	O
and	O
authenticates	O
it	O
and	O
then	O
sends	O
it	O
to	O
the	O
destination	O
VPN	B-Application
peer	O
over	O
a	O
specially	O
initiated	O
UDP	B-Protocol
connection	O
.	O
</s>
<s>
Hamachi	B-Application
currently	O
handles	O
tunneling	B-Protocol
of	O
IP	B-Protocol
traffic	O
including	O
broadcasts	B-Operating_System
and	O
multicast	O
.	O
</s>
<s>
The	O
Windows	O
version	O
also	O
recognizes	O
and	O
tunnels	B-Protocol
IPX	B-Protocol
traffic	O
.	O
</s>
<s>
The	O
synchronization	O
step	O
brings	O
a	O
client	O
's	O
view	O
of	O
its	O
private	B-Protocol
networks	I-Protocol
in	O
sync	O
with	O
other	O
members	O
of	O
these	O
networks	O
.	O
</s>
<s>
When	O
a	O
member	O
of	O
a	O
network	O
goes	O
online	O
or	O
offline	O
,	O
the	O
server	O
instructs	O
other	O
network	O
peers	O
to	O
either	O
establish	O
or	O
tear	O
down	O
tunnels	B-Protocol
to	O
the	O
former	O
.	O
</s>
<s>
When	O
establishing	O
tunnels	B-Protocol
between	O
the	O
peers	O
,	O
Hamachi	B-Application
uses	O
a	O
server-assisted	O
NAT	B-Protocol
traversal	I-Protocol
technique	O
,	O
similar	O
to	O
UDP	B-Protocol
hole	O
punching	O
.	O
</s>
<s>
This	O
process	O
does	O
not	O
work	O
on	O
certain	O
combinations	O
of	O
NAT	B-Protocol
devices	I-Protocol
,	O
requiring	O
the	O
user	O
to	O
explicitly	O
set	O
up	O
a	O
port	B-Protocol
forward	I-Protocol
.	O
</s>
<s>
In	O
the	O
event	O
of	O
unexpectedly	O
losing	O
a	O
connection	O
to	O
the	O
server	O
,	O
the	O
client	O
retains	O
all	O
its	O
tunnels	B-Protocol
and	O
starts	O
actively	O
checking	O
their	O
status	O
.	O
</s>
<s>
This	O
enables	O
Hamachi	B-Application
tunnels	B-Protocol
to	O
withstand	O
transient	O
network	O
problems	O
on	O
the	O
route	O
between	O
the	O
client	O
and	O
the	O
server	O
as	O
well	O
as	O
short	O
periods	O
of	O
complete	O
server	O
unavailability	O
.	O
</s>
<s>
Some	O
Hamachi	B-Application
clients	O
also	O
get	O
closed	O
port	O
on	O
other	O
clients	O
,	O
which	O
cannot	O
be	O
repaired	O
by	O
port	B-Protocol
forwarding	I-Protocol
.	O
</s>
<s>
Hamachi	B-Application
is	O
frequently	O
used	O
for	O
gaming	O
and	O
remote	O
administration	O
.	O
</s>
<s>
In	O
February	O
2007	O
,	O
an	O
IP-level	O
block	O
was	O
imposed	O
by	O
Hamachi	B-Application
servers	O
on	O
parts	O
of	O
Vietnamese	O
Internet	O
space	O
due	O
to	O
"	O
the	O
scale	O
of	O
the	O
system	O
abuse	O
originating	O
from	O
blocked	O
addresses	O
"	O
.	O
</s>
<s>
Each	O
Hamachi	B-Application
client	O
is	O
normally	O
assigned	O
an	O
IP	B-Protocol
address	I-Protocol
when	O
it	O
logs	O
into	O
the	O
system	O
for	O
the	O
first	O
time	O
.	O
</s>
<s>
To	O
avoid	O
conflicting	O
with	O
existing	O
private	B-Protocol
networks	I-Protocol
on	O
the	O
client	O
side	O
the	O
normal	O
private	B-Protocol
IP	I-Protocol
address	I-Protocol
blocks	I-Protocol
10.0.0.0/8	B-Protocol
,	O
172.16.0.0/12	B-Protocol
and	O
192.168.0.0/16	B-Protocol
are	O
not	O
used	O
.	O
</s>
<s>
Hamachi	B-Application
switched	O
to	O
the	O
25.0.0.0/8	O
block	O
.	O
</s>
<s>
The	O
client	O
now	O
supports	O
IPv6	B-Protocol
,	O
and	O
if	O
this	O
is	O
selected	O
then	O
the	O
address	O
assigned	O
is	O
picked	O
from	O
a	O
range	O
registered	O
to	O
LogMeIn	B-Application
.	O
</s>
<s>
The	O
IP	B-Protocol
address	I-Protocol
assigned	O
to	O
the	O
Hamachi	B-Application
client	O
is	O
henceforth	O
associated	O
with	O
the	O
client	O
's	O
public	B-Application
crypto	I-Application
key	I-Application
.	O
</s>
<s>
As	O
long	O
as	O
the	O
client	O
retains	O
its	O
key	O
,	O
it	O
can	O
log	O
into	O
the	O
system	O
and	O
use	O
this	O
IP	B-Protocol
address	I-Protocol
.	O
</s>
<s>
Hamachi	B-Application
creates	O
a	O
single	O
broadcast	B-Operating_System
domain	O
between	O
all	O
clients	O
.	O
</s>
<s>
This	O
makes	O
it	O
possible	O
to	O
use	O
LAN	B-General_Concept
protocols	O
that	O
rely	O
on	O
IP	B-Protocol
broadcasts	B-Operating_System
for	O
discovery	O
and	O
announcement	O
services	O
over	O
Hamachi	B-Application
networks	O
.	O
</s>
<s>
The	O
following	O
considerations	O
apply	O
to	O
Hamachi	B-Application
's	O
use	O
as	O
a	O
VPN	B-Application
application	O
:	O
</s>
<s>
The	O
security	O
risks	O
due	O
to	O
vulnerable	O
services	O
on	O
remote	O
machines	O
otherwise	O
not	O
accessible	O
behind	O
a	O
firewall	O
,	O
common	O
to	O
all	O
VPNs	B-Application
.	O
</s>
<s>
Hamachi	B-Application
is	O
stated	O
to	O
use	O
strong	O
,	O
industry-standard	O
algorithms	O
to	O
secure	O
and	O
authenticate	O
the	O
data	O
and	O
its	O
security	O
architecture	O
is	O
open	O
.	O
</s>
<s>
This	O
server	O
stores	O
the	O
nickname	O
,	O
maintenance	O
password	O
,	O
statically-allocated	O
25.0.0.0/8	O
IP	B-Protocol
address	I-Protocol
and	O
the	O
associated	O
authentication	O
token	O
of	O
the	O
user	O
.	O
</s>
<s>
As	O
such	O
,	O
it	O
can	O
potentially	O
log	O
actual	O
IP	B-Protocol
addresses	I-Protocol
of	O
the	O
VPN	B-Application
users	O
as	O
well	O
as	O
various	O
details	O
of	O
the	O
session	O
.	O
</s>
<s>
The	O
current	O
builds	O
of	O
Hamachi	B-Application
are	O
available	O
for	O
the	O
following	O
operating	B-General_Concept
systems	I-General_Concept
:	O
</s>
<s>
macOS	B-Application
(	O
Mac	B-Device
OS	I-Device
X	I-Device
10.6	I-Device
or	O
newer	O
,	O
which	O
run	O
only	O
on	O
x86	O
,	O
not	O
PowerPC	O
or	O
Apple	O
Silicon	O
(	O
ARM	O
)	O
.	O
)	O
</s>
<s>
Linux	B-Application
(	O
officially	O
supported	O
on	O
Ubuntu	O
16.04	O
or	O
newer	O
/	O
CentOS	O
7.2	O
or	O
newer	O
-	O
x86/x64	O
,	O
beta	O
armel/armhf	O
versions	O
available	O
)	O
Note	O
:	O
Stability	O
issues	O
on	O
Ubuntu	O
20.04	O
LTS	O
.	O
</s>
<s>
FreeBSD	B-Operating_System
users	O
can	O
install	O
and	O
utilize	O
Linux	B-Application
version	O
,	O
there	O
's	O
a	O
port	O
created	O
in	O
FreeBSD	B-Application
Ports	I-Application
.	O
</s>
<s>
Prior	O
to	O
versions	O
1.0.2.0	O
and	O
1.0.2.1	O
for	O
the	O
Windows	O
release	O
,	O
many	O
Windows	B-Application
Vista	I-Application
users	O
had	O
experienced	O
compatibility	O
and	O
connection	O
issues	O
while	O
using	O
Hamachi	B-Application
.	O
</s>
<s>
As	O
of	O
March	O
30	O
,	O
2007	O
,	O
the	O
software	O
now	O
includes	O
Vista	B-Application
tweaks	O
,	O
which	O
answer	O
these	O
OS-related	B-General_Concept
problems	O
,	O
among	O
other	O
specific	O
solutions	O
.	O
</s>
