add missing control messages to the manual page, including
addmulti, remmulti, scanbs, bridge and headersonly.

Notes:
Fri May 7 12:21:19 EDT 2010 geoff
    see ip(3), not ether(3).


Reference: /n/sources/patch/maybe/man-ether
Date: Thu May  6 15:32:17 CES 2010
Signed-off-by: quanstro@quantro.net
Reviewed-by: geoff

--- /sys/man/3/ether	Thu May  6 15:30:49 2010
+++ /sys/man/3/ether	Thu May  6 15:30:48 2010
@@ -67,8 +67,8 @@
 is a decimal integer constant identifying the Ethernet packet type.
 A type of \-1 enables the connection to receive copies of packets of
 all types.  A type of \-2 enables the connection to receive copies of
-the first 64 bytes of packets of all types.
-If multiple connections are assigned to a given packet type
+the first 64 bytes of packets of all types.  Other types must be unique.
+If multiple connections may receive a given packet type,
 a copy of each packet is passed up each connection.
 .PP
 Some interfaces also accept unique options when written to the
@@ -94,9 +94,20 @@
 contains device-specific data and statistics about the card.
 .PP
 An interface normally receives only those packets whose 
-destination address is that of the interface or is the
+destination address is that of the interface, the
 broadcast address,
-.BR ff:ff:ff:ff:ff:ff .
+.BR ff:ff:ff:ff:ff:ff ,
+or a a multicast address assigned to the interface.
+Multicast addresses are added by writing
+.B addmulti
+.I ea
+and remove by writing
+.B remmulti
+.I ea
+to the
+.B ctl
+file.  Multicast addresses are automatically dropped when
+the connection is closed.
 The interface can be made to receive all packets on the
 network by writing the string 
 .B promiscuous
@@ -104,8 +115,35 @@
 .B ctl
 file. 
 The interface remains promiscuous until the control file is
-closed.
-The extra packets are passed up connections only of types \-1
-and \-2.
+closed by all connections requesting promiscuous mode.
+The extra packets are passed up connections of types \-1
+and \-2 only.
+.PP
+Writing
+.B bridge
+to the
+.B ctl
+file causes loop back packets to be ignored.  This is useful for
+layer 3 bridging.
+Writing
+.B scanbs
+[
+.I secs
+]
+starts a scan for wireless base stations and sets the
+scanning interval to
+.IR secs.
+Scanning is terminated when the connection is closed.
+The default interval is 5s.  
+For wired connections, this command is ignored.
+.PP
+Writing
+.B headersonly
+causes the connection to return only the first
+58 bytes of the packet followed by a two-byte
+length and a four-byte time in machine ticks.
+Both numbers are in big-endian format.
 .SH SOURCE
 .B /sys/src/9/*/devether.c
+.br
+.B /sys/src/9/port/netif.c