winipcfg or ipconfig /renew equivalent under Linux

[i]

I have to say I'm surprised I've never needed to know this before. If I have a Linux system on a network and power it up while the DHCP server is down, how the heck do I later get it to request an IP address once the DHCP server is back up?

 

[Mercutio]

If an interface is specified as controlled by DHCP, I believe it will continue to make requests until it receives an address.
You could always ifconfig your DHCPless interface to something static and then do "ifconfig eth0 (or whatever) auto-dhcp" when your server is back up and running.

 

[i]

If an interface is specified as controlled by DHCP, I believe it will continue to make requests until it receives an address.

That would be an intelligent option, and you'd think that's what would happen. But no...

 

[Mercutio]

Is there anything in /etc/dhclient.conf?
Mine are blank and I can't ever recall putting anything in that file but it's the place to put DHCP client options...

 

[i]

Mine has a load of sample configurations, but they're all commented out.

I've since restarted this system of course, so I'm up and running. It's still frustrating me that I don't know the answer to such a simple question. I'll have to play around with dhclient. Presumably there's some way to nudge it into doing something if it's either exited or just sitting there unhelpfully.

 

[Mercutio]

The dhclient.conf man page says the default time to rebroadcast a DHCP request is five minutes. Should be all magicky and just work.

 

[blakerwry]

redhat/fedora:

service network restart


Others:

ifconfig eth0 down
ifconfig eth0 up

 

[i]

ifconfig eth0 down
ifconfig eth0 up

Oh I tried that one. All it did was disable and then reenable the network. It had no effect on DHCP and whether I had an IP address or not. Kind of disappointing really.

 

[i]

Well that's it. I'm going to intentionally start my system up tonight without a DHCP server around and see how things play out. I'll post back here with the results.