[ntp:questions] multicast - wrong interface

Martin martin at pr41.sk
Wed Feb 14 17:08:06 UTC 2007

Hello !

My NTP server sends all multicast traffic from eth0 and I don't
know how to configure it to send it to the LAN connected via eth2.
The details are below. Could you please give me some
hints or help ?

Thank you


- - - - - -

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

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

but the output from ntp -D2 shows, that NTP has chosen eth0 (fd #18) and
not eth2 (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=, 
	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=, 
	MCAST   ***** sendpkt(fd=18 dst=, src=217.XX.XXX.XX, ttl=96, len=68)

(BTW, why is ttl=96 and not 3 ? But that's not the problem.)

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