oping(8): Document the new SetUID behavior in connection with the "-f" option.

[liboping.git] / src / mans / oping.pod

diff --git a/src/mans/oping.pod b/src/mans/oping.pod
index 90d6b02..e076299 100644 (file)
--- a/src/mans/oping.pod
+++ b/src/mans/oping.pod
@@ -66,10 +66,18 @@ Set the outgoing network device to use.
 Instead of specifying hostnames on the command line, read them from
 I<filename>. If I<filename> is B<->, read from C<STDIN>.
 
-If the real user ID (as returned by L<getuid(2)>) and the effective user ID (as
+If I<oping> is installed with the SetUID-bit, it will set the effective UID to
+the real UID before opening the file. In the special (but common) case that
+I<oping> is owned by the super-user (UIDE<nbsp>0), this means that privileges
+are temporarily dropped before opening the file, in order to prevent users from
+reading arbitrary files on the system.
+
+If your system doesn't provide I<saved set-user IDs> (this was an optional
+feature before POSIXE<nbsp>2001), the behavior is different because it is not
+possible to I<temporarily> drop privileges. The alternative behavior is: If the
+real user ID (as returned by L<getuid(2)>) and the effective user ID (as
 returned by L<geteuid(2)>) differ, the only argument allowed for this option is
-"-" (i.E<nbsp>e. standard input). This is meant to avoid security issues when
-I<oping> is installed with the SUID-bit.
+"-" (i.e. standard input).
 
 =item B<-Q> I<qos>
 
@@ -78,17 +86,28 @@ somewhat tricky option, since the meaning of the bits in the IPv4 header has
 been revised several times.
 
 The currently recommended method is I<Differentiated Services> which is used in
-IPv6 headers as well. There are shortcuts for 13E<nbsp>predefined
+IPv6 headers as well. There are shortcuts for various predefined
 I<per-hop behaviors> (PHBs):
 
 =over 4
 
+=item B<be>
+
+Selects the I<Best Effort> behavior. This is the default behavior.
+
 =item B<ef>
 
 Selects the I<Expedited Forwarding> (EF) per-hop behavior, as defined in
 I<RFCE<nbsp>3246>. This PHB is characterised by low delay, low loss and low
 jitter, i.e. high priority traffic.
 
+=item B<va>
+
+Selects the I<Voice Admitted> (VA) per-hop behavior, as defined in
+I<RFCE<nbsp>5865>. This traffic class is meant for I<Voice over IP> (VoIP)
+traffic which uses I<Call Admission Control> (CAC) for reserving network
+capacity.
+
 =item  B<af>I<c>I<p>
 
 Selects one of 12E<nbsp>differentiated services code points (DSCPs), which are
@@ -98,6 +117,13 @@ betweenE<nbsp>1 throughE<nbsp>3, for example "af13", "af22" and "af41". In each
 class, the lower priority number takes precedence over the higher priority
 number.
 
+=item B<cs>I<n>
+
+Selects one of the eight I<Class Selector> PHBs. I<n> is a number
+betweenE<nbsp>0 throughE<nbsp>7. The class selectors have been defined to be
+compatible to the I<Precedence> field in the IPv4 header as defined in
+I<RFCE<nbsp>791>. Please note that "cs0" is synonymous to "be".
+
 =back
 
 The old definition of the same bits in the IPv4 header was as I<Type of
@@ -130,6 +156,16 @@ decimal number (0-255), a hexadecimal number (0x00-0xff) or an octal number
 (00-0377) using the usual "0x" and "0" prefixes for hexadecimal and octal
 respectively.
 
+The printed lines will contain information about the QoS field of received
+packets if either a non-standard QoS setting was used on outgoing packets or if
+the QoS byte of incoming packets is not zero. In other words, the QoS
+information is omitted if both, the outgoing and the incoming QoS bytes are
+zero. The received byte is always interpreted as
+I<Differentiated Services Code Point> (DSCP) and
+I<Explicit Congestion Notification> (ECN), even if the deprecated
+I<Type of Service> (ToS) aliases were used to specify the bits of outgoing
+packets.
+
 =back
 
 =head1 COLORS
@@ -154,7 +190,7 @@ L<ping(8)>, L<http://www.fping.com/>, L<liboping(3)>
 
 =head1 AUTHOR
 
-liboping is written by Florian octo Forster E<lt>octo at verplant.orgE<gt>.
+liboping is written by Florian octo Forster E<lt>ff at octo.itE<gt>.
 Its homepage can be found at L<http://verplant.org/liboping/>.
 
 (c) 2005-2010 by Florian octo Forster.