Re: tlug: IP "refresh" (cable modem/router)

["Andrew S. Howell" <andy@example.com>]

>>>>> "Shawn" == Atlas21 Shawn <gray_s@example.com> writes:

    Shawn> I was wondering about how linux goes about
    Shawn> renewing/refreshing (my japanese win95 says "henshin") the
    Shawn> IP.

    Shawn> What should I do with Linux to get the same results? What
    Shawn> is the linux equivalent of winipcfg?

Shawn,

	Not sure if you got your answer to this or not. This is done
using dhcp protocol. The daemon dhcpcd makes a request to the cable
modem. It gets back a IP, along with a lease saying how long it is
good for. If you look in /var/log/messages, you should see something
like:

pr 22 17:53:50 localhost dhcpcd[12510]: msg from the DHCP server: NAK: Address does not belong to requesting client 
Apr 22 17:53:50 localhost dhcpcd[12510]: REBOOTING: got DHCPNAK. Fall back to INIT 
Apr 22 17:54:06 localhost dhcpcd[12510]: assigned IP address:        172.16.50.66 
Apr 22 17:54:06 localhost dhcpcd[12510]: assigned subnetmask:        255.255.248.0 
Apr 22 17:54:06 localhost dhcpcd[12510]: got in BOUND state 

>From dchpcd's man page:       

	dhcpcd is an implementation of the DHCP client specified in
RFC2131 (when -r option is not specified) and RFC1541 (when -r option
is specified).

It gets the host information (IP address, netmask, broadcast address,
etc.) from a DHCP server and configures the network interface of the
machine on which it is running. It also tries to renew the lease time
according to RFC2131 or RFC1541 (obsolete). 

The cable modem will specify how long to lease is good for, and how
often it should be renewed. dchpcd will keep trying to renew to lease, 
which the cable modem will normal grant. With my provider, it there is 
no traffic for 12-18 hours, then it denies the lease.

So, depending on your provider, you may be able to keep the lease
indefinitely.

Regards,

	Andy
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