<s>
FTP	B-Protocol
server	B-Application
return	O
codes	O
always	O
have	O
three	O
digits	O
,	O
and	O
each	O
digit	O
has	O
a	O
special	O
meaning	O
.	O
</s>
<s>
(	O
The	O
user-process	O
sending	O
another	O
command	O
before	O
the	O
completion	O
reply	O
would	O
be	O
in	O
violation	O
of	O
protocol	O
;	O
but	O
server-FTP	O
processes	O
should	O
queue	O
any	O
commands	O
that	O
arrive	O
while	O
a	O
preceding	O
command	O
is	O
in	O
progress	O
.	O
)	O
</s>
<s>
The	O
server-FTP	O
process	O
may	O
send	O
at	O
most	O
,	O
one	O
1xx	O
reply	O
per	O
command	O
.	O
</s>
<s>
It	O
is	O
difficult	O
to	O
assign	O
a	O
meaning	O
to	O
"	O
transient	O
"	O
,	O
particularly	O
when	O
two	O
distinct	O
sites	O
(	O
Server	B-Application
-	O
and	O
User-processes	O
)	O
have	O
to	O
agree	O
on	O
the	O
interpretation	O
.	O
</s>
<s>
A	O
rule	O
of	O
thumb	O
in	O
determining	O
if	O
a	O
reply	O
fits	O
into	O
the	O
4xx	O
or	O
the	O
5xx	O
(	O
Permanent	O
Negative	O
)	O
category	O
is	O
that	O
replies	O
are	O
4xx	O
if	O
the	O
commands	O
can	O
be	O
repeated	O
without	O
any	O
change	O
in	O
command	O
form	O
or	O
in	O
properties	O
of	O
the	O
User	O
or	O
Server	B-Application
(	O
e.g.	O
,	O
the	O
command	O
is	O
spelled	O
the	O
same	O
with	O
the	O
same	O
arguments	O
used	O
;	O
the	O
user	O
does	O
not	O
change	O
his	O
file	O
access	O
or	O
user	O
name	O
;	O
the	O
server	B-Application
does	O
not	O
put	O
up	O
a	O
new	O
implementation	O
.	O
)	O
</s>
<s>
The	O
RFC	O
2228	O
introduced	O
the	O
concept	O
of	O
protected	O
replies	O
to	O
increase	O
security	O
over	O
the	O
FTP	B-Protocol
communications	O
.	O
</s>
<s>
The	O
6xx	O
replies	O
are	O
Base64	B-Protocol
encoded	O
protected	O
messages	O
that	O
serves	O
as	O
responses	O
to	O
secure	O
commands	O
.	O
</s>
<s>
These	O
replies	O
indicate	O
the	O
status	O
of	O
the	O
Server	B-Application
file	O
system	O
vis-a-vis	O
the	O
requested	O
transfer	O
or	O
other	O
file	O
system	O
action	O
.	O
</s>
<s>
Below	O
is	O
a	O
list	O
of	O
all	O
known	O
return	O
codes	O
that	O
may	O
be	O
issued	O
by	O
an	O
FTP	B-Protocol
server	B-Application
.	O
</s>
<s>
In	O
this	O
case	O
,	O
the	O
text	O
is	O
exact	O
and	O
not	O
left	O
to	O
the	O
particular	O
implementation	O
;	O
it	O
must	O
read	O
:	O
MARK	O
yyyy	O
=	O
mmmm	O
where	O
yyyy	O
is	O
User-process	O
data	O
stream	O
marker	O
,	O
and	O
mmmm	O
server	B-Application
's	O
equivalent	O
marker	O
(	O
note	O
the	O
spaces	O
between	O
markers	O
and	O
"	O
=	O
"	O
)	O
.	O
</s>
<s>
Explains	O
how	O
to	O
use	O
the	O
server	B-Application
or	O
the	O
meaning	O
of	O
a	O
particular	O
non-standard	O
command	O
.	O
</s>
<s>
234	O
Server	B-Application
accepts	O
the	O
security	O
mechanism	O
specified	O
by	O
the	O
client	O
;	O
no	O
security	O
data	O
needs	O
to	O
be	O
exchanged	O
.	O
</s>
<s>
10000	O
SeriesCommon	O
Winsock	O
Error	O
CodesWindows	O
Socket	O
Error	O
Codes	O
,	O
Microsoft	O
Windows	O
Dev	O
Center	O
(	O
These	O
are	O
not	O
FTP	B-Protocol
return	O
codes	O
)	O
10054Connection	O
reset	O
by	O
peer	O
.	O
</s>
<s>
10060Cannot	O
connect	O
to	O
remote	O
server	B-Application
.	O
</s>
<s>
10061Cannot	O
connect	O
to	O
remote	O
server	B-Application
.	O
</s>
<s>
The	O
connection	O
is	O
actively	O
refused	O
by	O
the	O
server	B-Application
.	O
</s>
<s>
10068Too	O
many	O
users	O
,	O
server	B-Application
is	O
full	O
.	O
</s>
