On Fri, 2009-10-02 at 23:40 +0530, sathya sai wrote: [...] > But, when I reconfigure my network interface with the below ifconfig > command, I am shocked that the above netlink program is giving me two > notifications with RTM_NEWADDR (new address being added to an > interface) > > I am not sure why the second ifconfig command gives me the two > RTM_NEWADDR netlink notifications? > > ifconfig eth0 inet 0 > ifconfig eth0 inet 10.208.34.114 netmask 255.255.255.0 > > To analyse further on this, I then changed the second ifconfig to as > in below(removed the netmask part), > > ifconfig eth0 inet 10.208.34.114 > > Now I am getting only one RTM_NEWADDR netlink notification from the > kernel.(although the netmask and broadcast address as been assigned to > the default address by the kernel). > > Could you please help me out by answering why with my prior netlink > command the debian kernel was triggering two RTM_NEWADDR > notifications.
If I run:
strace ifconfig eth0 inet 10.208.34.114 netmask 255.255.255.0
it shows me:
ioctl(4, SIOCSIFADDR, 0xff97ca88) = 0
ioctl(4, SIOCGIFFLAGS, {ifr_name="eth0",
ifr_flags=IFF_UP|IFF_BROADCAST|IFF_MULTICAST}) = 0
ioctl(4, SIOCSIFFLAGS, 0xff97c98c) = 0
ioctl(4, SIOCSIFNETMASK, 0xff97ca88) = 0
So the address and netmask configuration are two separation operations
that are notified separately.
Ben.
--
Ben Hutchings
Who are all these weirdos? - David Bowie, about L-Space IRC channel #afp
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