.B ENOENT
.RI ( "No such file or directory" ).
.PP
+If a read error occurs, or the directory
+.B /etc/authbind
+cannot be accessed, then not only will
+.B bind
+fail, but an error message will be printed to stderr. Unrecognised
+lines in
+.BI /etc/authbind/byuid/ uid
+files are silently ignored, as are lines whose
+.I addr
+has non-zero bits more than
+.I length
+from the top or where some
+.I min
+is larger than
+.IR max .
+.SH EXAMPLE
So for example an attempt by uid 432
-to bind to [2620:106:e002:f00f::21]:80
+to bind to port 80 of address [2620:106:e002:f00f::21]
would result in authbind calling
.I access(2)
on, in order,
.br
.B ::/0,80
.RE
-.PP
-If a read error occurs, or the directory
-.B /etc/authbind
-cannot be accessed, then not only will
-.B bind
-fail, but an error message will be printed to stderr. Unrecognised
-lines in
-.BI /etc/authbind/byuid/ uid
-files are silently ignored (as are lines whose
-.I addr
-has non-zero bits more than
-.I length
-from the top) or where some
-.I min
-is larger than
-.IR max .
-.PP
+.SH PORTS 512-1023
Authorising binding to ports from 512 to 1023 inclusive is
not recommended. Some protocols (including some versions of NFS)
authorise clients by seeing that they are using a port number in this
range. So by authorising a program to be a server for such a port,
you are also authorising it to impersonate the whole host for those
-protocols. To make sure that this isn't done by accident,
+protocols.
+
+To make sure that this isn't done by accident,
if the port number requested is in the range 512-1023, authbind
will expect the permission files to have an additional
.B !