In message <20020721235210.B8B9AD4F2@ns1.vrx.net>, jfw writes:
>My ISP has just changed their servers, and now requires users with static IP
>to use DHCP.  (More precisely, when I called, I was specifically told that
>those few users who still had static IP addresses would need to "check the
>Use DHCP box in the Windows TCP/IP Control Panel", and until I've at least
>tried the equivalent of this, arguing about how loony this sounds isn't going
>to help.)
>
>When I fire up dhclient, however, it sets the address of the PPP link to 0
>(specifically "inet 0.0.0.0 -> 255.255.255.255 netmask 0xff000000"), and
>then proceeds to fail miserably:
>
>Listening on BPF/ppp0/00:00:00:00:00
>Sending on   BPF/ppp0/00:00:00:00:00
>Sending on   Socket/fallback
>DHCPDISCOVER on ppp0 to 255.255.255.255 port 67 interval 5
>send_packet: Input/output error
>DHCPDISCOVER on ppp0 to 255.255.255.255 port 67 interval 13
>send_packet: Input/output error
>DHCPDISCOVER on ppp0 to 255.255.255.255 port 67 interval 7
>send_packet: Input/output error
>DHCPDISCOVER on ppp0 to 255.255.255.255 port 67 interval 8
>send_packet: Input/output error
>DHCPDISCOVER on ppp0 to 255.255.255.255 port 67 interval 13
>send_packet: Input/output error
>DHCPDISCOVER on ppp0 to 255.255.255.255 port 67 interval 10
>send_packet: Input/output error
>DHCPDISCOVER on ppp0 to 255.255.255.255 port 67 interval 5
>send_packet: Input/output error
>No DHCPOFFERS received.
>No working leases in persistent database - sleeping.
>
>
>So:  does anyone use dhclient over PPP?  How do I configure it to work
>properly without blindly hammering the ppp0 interface address?  (Or at
>least hammering it in such a way that it will actually work.)  And does
>anyone believe that sending a dhcp request will convince their dialup
>network to re-issue my static address like the phone clone promised?
>

You can't run dhcp over ppp -- ppp has its own dynamic address 
assignment mechanisms.  Is this PPPoE or dialup?  I haven't played with 
the former; for the latter, address assignment should just work, 
though you may need an ip-up or ip-down script to handle DNS 
assignment.  But if you've been using ppp with a static IP address, you 
may have that set in your ppp/peers file, and you'll have to pull it 
out.  (I suspect that all of this is true for PPPoE as well, but as I 
said I haven't tried it.)

		--Steve Bellovin, http://www.research.att.com/~smb (me)
		http://www.wilyhacker.com ("Firewalls" book)