[ntp:bugs] [Bug 785] New: unable to select multicast (IPv4) source interface

[Martin H via the NTP Bugzilla]

http://bugs.ntp.isc.org/785

           Summary: unable to select multicast (IPv4) source interface
           Product: ntp
           Version: 4.2.4
          Platform: PC
        OS/Version: Linux
            Status: NEW
          Severity: normal
          Priority: P3
         Component: ntpd
        AssignedTo: stenn at ntp.org
        ReportedBy: martin at pr41.sk
                CC: bugs at ntp.isc.org


I need to configure the ntpd to send the multicast traffic from the eth2
interface, but the server uses eth0.

There are two related problems:
1.It is not possible to specify the interface in the configuration file.
2.The server selects the wrong interface.

In my ntp.conf there is:
	broadcast 224.0.1.1 key 145 ttl 3

and the linux kernel has a route for class D addresses, which uses eth2:
	Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
	224.0.0.0       *               240.0.0.0       U     0      0        0 eth2

but the output from ntp -D2 shows, that NTP has chosen eth0 (fd #18) and
not eth2 (also verified with tcpdump):
	created interface #2: fd=18, bfd=-1, name=eth0, flags=0x19, scope=0, 
ifindex=0, sin=217.XX.XXX.XX, bcast=217.XX.XXX.223,, mask=255.255.255.224, 
Enabled:
	......
	created interface #3: fd=19, bfd=-1, name=eth2, flags=0x19, scope=0, 
ifindex=0, sin=192.168.XX.XX, bcast=192.168.XX.255,, mask=255.255.255.0, 
Enabled:
	......
	MCAST   ***** sendpkt(fd=18 dst=224.0.1.1, src=217.XX.XXX.XX, ttl=96, len=68)

-- 
Martin H <martin at pr41.sk>



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