DHCP DECLINE from ISC DHCP Client 4.1.2

Shreyansh shrey.linux at gmail.com
Sat Dec 22 08:47:32 UTC 2012


Hi list,

Since the last few days, I have been looking into the RFC2131 (DHCP) and for 
implementation referring to ISC DHCP Client (4.1.2), trying to understand 
sections of code for some future work. When I was reading through DHCP Decline 
in RFC, and then trying to relate it with its implementation, I observed that:

1. Function send_decline is called from function bind_lease() 
[client/dhclient.c]
2. The script parameters to be passed to /sbin/dhclient-script are created by 
bind_lease() contain "BOUND|RENEW|REBOOT|REBIND". No mention of "ARPSEND" and 
"ARPCHECK" is present.
3. When I look into the file /sbin/dhclient-script, I notice that the scripts 
main code has implementation of $reason variable being "ARPCHECK" and "ARPSEND" 
but neither the does the script internally call it, nor the dhclient.c file 
functions are calling it.

I searched through the previous posting of similar issue and found an old post 
here: http://article.gmane.org/gmane.network.dhcp.isc.dhcp-
client/530/match=decline

Then, I tried to search for previous or recent most version which might have had 
such a change, but could find none.

After reading through other posts and various opinion (voiced in mailing list on 
similar issue), I am of the opinion that DECLINE has not been implemented in ISC 
DHCP 4.1.2 source (in fact 4.* version, but I am still to confirm once again). 
In fact, people are of opinion that it is not a responsibility of dhclient-
script to send ARP (assuming what if environment doesn't support ARP), but 
should be directly implemented in dhclient binary.

In fact, the man pages of Dhclient-script too doesn't talk about ARPSEND or 
ARPCHECK. [The recent version of man pages I could find].

Can some one please help in correcting my understanding above? Any suggestions 
or pointer too would be great.

-
Shreyansh 



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