[NCLUG] dhcpcd and pump

[Mark Fassler]

I've got a RedHat Linux machine on a mostly Windows network.

When the Windows machines request an IP address via dhcp, they get a lease 
time of 8 days.  

The Linux box, by default, requests a lease time of 1 hour, and the server 
happily provides it with that.  By default, RedHat uses pump.

If I change /etc/sysconfig/network-scripts/ifup to call pump like this: 
"pump -l 192" then the machine requests an 8 day lease and gets it.  The 
problem is that the machine only does a renewal only after 7 days, so, 
worst case scenario, if the machine is off for 1 day, it will lose its IP 
address.  This is a problem for this user's application.  (The network 
admin doesn't want to give static IP addresses.  He figures with an 8 day 
lease, you pratically have a static IP.)

So if I remove pump, RedHat defaults to using dhcpcd.  dhcpcd requests an 
infinite lease and the server gives it an 8 day lease.  dhcpcd then renews 
its lease every 4 days.  This is acceptable, since even on a three day 
weekend, the machine would be down for just under 4 days.  

I could do a cron-type thing that forces a renew once a day...  or I could 
do a shutdown-type thing that forces a renew upon shutdown... but I'd 
rather have a dhcp client that just plays nice (after all, dhcp is 
supposed to be "plug and play".)  

Is there a reason that Redhat prefers pump over dhcpcd?  (I don't want to 
use dhcpcd only to discover that it has its own set of special "features" 
that I'll hate.)  Is pump not totally RFC-compliant?  Are there flags for 
either dhcpcd or pump that control renewal time? (I've found them for 
lease time, but not renewal).

Anyway, if someone's resolved this problem before, I'd be grateful to hear 
about it (before I go willy-nilly creating more scripts that I have to 
keep track of).

--
Mark Fassler
fassler at monkeysoft.net