<s>
In	O
computing	O
,	O
syslog	B-Protocol
is	O
a	O
standard	O
for	O
message	B-Application
logging	I-Application
.	O
</s>
<s>
Computer	O
system	O
designers	O
may	O
use	O
syslog	B-Protocol
for	O
system	O
management	O
and	O
security	O
auditing	O
as	O
well	O
as	O
general	O
informational	O
,	O
analysis	O
,	O
and	O
debugging	O
messages	O
.	O
</s>
<s>
A	O
wide	O
variety	O
of	O
devices	O
,	O
such	O
as	O
printers	O
,	O
routers	B-Protocol
,	O
and	O
message	O
receivers	O
across	O
many	O
platforms	O
use	O
the	O
syslog	B-Protocol
standard	O
.	O
</s>
<s>
This	O
permits	O
the	O
consolidation	O
of	O
logging	B-Application
data	O
from	O
different	O
types	O
of	O
systems	O
in	O
a	O
central	O
repository	O
.	O
</s>
<s>
Implementations	O
of	O
syslog	B-Protocol
exist	O
for	O
many	O
operating	O
systems	O
.	O
</s>
<s>
When	O
operating	O
over	O
a	O
network	O
,	O
syslog	B-Protocol
uses	O
a	O
client-server	B-Operating_System
architecture	I-Operating_System
where	O
a	O
syslog	B-Protocol
server	I-Protocol
listens	O
for	O
and	O
logs	O
messages	O
coming	O
from	O
clients	O
.	O
</s>
<s>
Syslog	B-Protocol
was	O
developed	O
in	O
the	O
1980s	O
by	O
Eric	O
Allman	O
as	O
part	O
of	O
the	O
Sendmail	B-Application
project	O
.	O
</s>
<s>
It	O
was	O
readily	O
adopted	O
by	O
other	O
applications	O
and	O
has	O
since	O
become	O
the	O
standard	O
logging	B-Application
solution	O
on	O
Unix-like	B-Operating_System
systems	I-Operating_System
.	O
</s>
<s>
A	O
variety	O
of	O
implementations	O
also	O
exist	O
on	O
other	O
operating	O
systems	O
and	O
it	O
is	O
commonly	O
found	O
in	O
network	O
devices	O
,	O
such	O
as	O
routers	B-Protocol
.	O
</s>
<s>
Syslog	B-Protocol
originally	O
functioned	O
as	O
a	O
de	O
facto	O
standard	O
,	O
without	O
any	O
authoritative	O
published	O
specification	O
,	O
and	O
many	O
implementations	O
existed	O
,	O
some	O
of	O
which	O
were	O
incompatible	O
.	O
</s>
<s>
Various	O
companies	O
have	O
attempted	O
to	O
claim	O
patents	O
for	O
specific	O
aspects	O
of	O
syslog	B-Protocol
implementations	O
.	O
</s>
<s>
The	O
information	O
provided	O
by	O
the	O
originator	O
of	O
a	O
syslog	B-Protocol
message	O
includes	O
the	O
facility	O
code	O
and	O
the	O
severity	O
level	O
.	O
</s>
<s>
The	O
syslog	B-Protocol
software	O
adds	O
information	O
to	O
the	O
information	O
header	O
before	O
passing	O
the	O
entry	O
to	O
the	O
syslog	B-Protocol
receiver	O
.	O
</s>
<s>
Such	O
components	O
include	O
an	O
originator	O
process	O
ID	O
,	O
a	O
timestamp	O
,	O
and	O
the	O
hostname	O
or	O
IP	B-Protocol
address	I-Protocol
of	O
the	O
device	O
.	O
</s>
<s>
A	O
facility	O
code	O
is	O
used	O
to	O
specify	O
the	O
type	O
of	O
system	O
that	O
is	O
logging	B-Application
the	O
message	O
.	O
</s>
<s>
The	O
mapping	O
between	O
facility	O
code	O
and	O
keyword	O
is	O
not	O
uniform	O
in	O
different	O
operating	O
systems	O
and	O
syslog	B-Protocol
implementations	O
.	O
</s>
<s>
Popular	O
syslog	B-Protocol
tools	O
such	O
as	O
Rsyslog	B-Protocol
conform	O
to	O
this	O
new	O
standard	O
.	O
</s>
<s>
Generated	O
log	O
messages	O
may	O
be	O
directed	O
to	O
various	O
destinations	O
including	O
console	B-Device
,	O
files	O
,	O
remote	O
syslog	B-Protocol
servers	I-Protocol
,	O
or	O
relays	O
.	O
</s>
<s>
Most	O
implementations	O
provide	O
a	O
command	O
line	O
utility	O
,	O
often	O
called	O
logger	O
,	O
as	O
well	O
as	O
a	O
software	B-Library
library	I-Library
,	O
to	O
send	O
messages	O
to	O
the	O
log	O
.	O
</s>
<s>
To	O
display	O
and	O
monitor	O
the	O
collected	O
logs	O
one	O
needs	O
to	O
use	O
a	O
client	O
application	O
or	O
access	O
the	O
log	B-Application
file	I-Application
directly	O
on	O
the	O
system	O
.	O
</s>
<s>
The	O
basic	O
command	O
line	O
tools	O
are	O
tail	B-Application
and	O
grep	B-Application
.	O
</s>
<s>
Some	O
implementations	O
include	O
reporting	O
programs	O
for	O
filtering	O
and	O
displaying	O
of	O
syslog	B-Protocol
messages	O
.	O
</s>
<s>
When	O
operating	O
over	O
a	O
network	O
,	O
syslog	B-Protocol
uses	O
a	O
client-server	B-Operating_System
architecture	I-Operating_System
where	O
the	O
server	O
listens	O
on	O
a	O
well-known	O
or	O
registered	B-Protocol
port	I-Protocol
for	O
protocol	O
requests	O
from	O
clients	O
.	O
</s>
<s>
Historically	O
the	O
most	O
common	O
transport	O
layer	O
protocol	O
for	O
network	O
logging	B-Application
has	O
been	O
User	B-Protocol
Datagram	I-Protocol
Protocol	I-Protocol
(	O
UDP	O
)	O
,	O
with	O
the	O
server	O
listening	O
on	O
port	O
514	O
.	O
</s>
<s>
Because	O
UDP	O
lacks	O
congestion	O
control	O
mechanisms	O
,	O
Transmission	B-Protocol
Control	I-Protocol
Protocol	I-Protocol
(	O
TCP	O
)	O
port	O
6514	O
is	O
used	O
;	O
Transport	B-Protocol
Layer	I-Protocol
Security	I-Protocol
is	O
also	O
required	O
in	O
implementations	O
and	O
recommended	O
for	O
general	O
use	O
.	O
</s>
<s>
A	O
syslog	B-Protocol
message	O
is	O
formatted	O
(	O
RFC	O
5424	O
gives	O
the	O
Augmented	O
Backus	O
–	O
Naur	O
form	O
(	O
ABNF	O
)	O
definition	O
)	O
,	O
but	O
its	O
MSG	O
field	O
is	O
not	O
.	O
</s>
<s>
Various	O
groups	O
are	O
working	O
on	O
draft	O
standards	O
detailing	O
the	O
use	O
of	O
syslog	B-Protocol
for	O
more	O
than	O
just	O
network	O
and	O
security	O
event	O
logging	B-Application
,	O
such	O
as	O
its	O
proposed	O
application	O
within	O
the	O
healthcare	O
environment	O
.	O
</s>
<s>
The	O
syslog	B-Protocol
format	O
has	O
proven	O
effective	O
in	O
consolidating	O
logs	O
,	O
as	O
there	O
are	O
many	O
open-source	O
and	O
proprietary	O
tools	O
for	O
reporting	O
and	O
analysis	O
of	O
these	O
logs	O
.	O
</s>
<s>
Utilities	O
exist	O
for	O
conversion	O
from	O
Windows	O
Event	O
Log	O
and	O
other	O
log	O
formats	O
to	O
syslog	B-Protocol
.	O
</s>
<s>
The	O
Syslog	B-Protocol
protocol	O
is	O
defined	O
by	O
Request	O
for	O
Comments	O
(	O
RFC	O
)	O
documents	O
published	O
by	O
the	O
Internet	O
Engineering	O
Task	O
Force	O
(	O
Internet	O
standards	O
)	O
.	O
</s>
<s>
The	O
following	O
is	O
a	O
list	O
of	O
RFCs	O
that	O
define	O
the	O
syslog	B-Protocol
protocol	O
:	O
</s>
