Re: [TCLUG:22054] Debian DHCP (was Re: [TCLUG:21970] Should DSL orCable modem)

[Adam Maloney <adamm@sihope.com>]

One correction:
> Yep.  This is the correct way of doing it.  The client *MUST* request
> an acceptable lease time, by protocol standards.  Remember, the

The client can request whatever it wants, there's nothing in 1541 or 2131
that says the client must request an "acceptable" lease.  By default
dhcpcd requests 0xffffffff.  It doesn't matter if the client requests
something outrageous like this, the server's max_lease_time will override
it anyways.  

Adam Maloney
Systems Administrator
Sihope Communications

On Tue, 3 Oct 2000, ^chewie wrote:

> On Tue, Oct 03, 2000 at 10:23:51AM -0500, Adam Maloney wrote:
> > No, if he tells the client to ask for a lease time of 3 weeks, the
> > client sends that during the negotiation. The server can reject that
> > lease time if it's too long with a NACK followed by another OFFER
> > with a more plausible lease time.
> 
> Yep.  This is the correct way of doing it.  The client *MUST* request
> an acceptable lease time, by protocol standards.  Remember, the
> server, in most cases, will defer to allowing you to keep your IP if
> you renew your license at refresh time.  The server will give the
> client fair warning before it thinks the lease will expire.  If the
> client's still there and submits an ACK, the server issues an extended
> lease.  If not, the server drops the lease back into the pool of free
> IP's.
> 
> As Adam said, it's bad if you continue to use an IP that the server
> considers free; at some time the server will reassign the IP to
> another machine and you WILL have IP collisions.  No one will be able
> to keep a consistent connection.
> 
> For more info on how to correctly set up your dhcpcd, pump, or
> dhcpclient, please refer to their respective man pages or read
> NET3-HOWTO at http://www.linuxdoc.org.
> 
> For debian users, it's fairly easy to set up dhcp on a given
> interface:
> 
> 1. Install your preferred client
> 2. Configure the client for your preferred NIC ( not needed for debian
> 	systems using dhcpcd, if you're not using the init.d script )
> 3. Make sure the client daemon does NOT start from init.d
> 	scripts.
> 	
> 	bash# update-rc.d -f dhcpcd remove
> 
> 4. Edit your /etc/network/interfaces file to have a line like
> 	the following.
> 
> 	##############################################################
> 	# Added for eth0 (see interfaces(5))
> 	iface eth0 inet dhcp
> 	    #######################################################
> 	    # DHCP options
> 
> 	    #<pump,dhcpcd>#
> 	    #hostname iwantthisone
> 	    #<pump>#
> 	    #leasehours leasetime
> 	    #<dhcpcd>#
> 	    #leasetime leasetime
> 	    #<dhcpcd>#
> 	    #vendor vendor
> 	    #<dhcpcd>#
> 	    #client client_id
> 	    
> 	    #######################################################
> 	    # Nice way to add interface specific scripts (ipchains,
> 	    # ipmasqadm, tunneling scripts, etc.)  Executes these as
> 	    # they come, though a neat way to do it is to use
> 	    # run-parts on a *.d directory
> 	    #
> 	    #{pre-up|up|down|post-down} command
> 
> 	    pre-up run-parts /etc/interfaces/eth0_pre-up.d || true
> 	    up run-parts /etc/interfaces/eth0_up.d || true
> 	    down run-parts /etc/interfaces/eth0_down.d || true
> 	    post-down run-parts /etc/interfaces/eth0_post-down.d || true
> 
> 	# end file snippit
> 	##############################################################
> 
> 5. Execute "/etc/init.d/networking restart", or use "ifdown eth0; ifup
> 	eth0"
> 
> Violla...
> 
> -- 
>   Chad "^chewie, gunnarr" Walstrom <chewie@wookimus.net>
>               http://wookimus.net/chewie
>