NormanSPremium,MVM
join:2001-02-14
San Jose, CA
kudos:4 Reviews:
 ·SONIC.NET
·Pacific Bell - SBC
3 edits | reply to msj
Re: DHCP Spoofing / Half Bridgingsaid by msj:I don't have one of these modems (I have the Actiontec GT701WG) but I was interested in finding out how these modems do what they do (and possibly adding the feature to the Actiontec in the future). So, from reading as much as I can find, I believe I understand how this works. The "DHCP Spoofing" part describes the process in which you get the external IP address on your machine. This process is the same as what has been done in the past with dumb (non routing) cable modems. When you first connect to the modem (or after power is cycled on the modem) the modem first delivers a local IP address to your machine, however the lease is very short). This allows you to connect to the modem and possibly do configuration, etc. Meanwhile the modem is establishing a connection via PPPoA to your ISP. Once it gets the external IP address to use it waits for the lease to expire. When your machines lease expires it makes a new request for an IP address via DHCP, and this time the modem gives you the external address with a normal lease. I assume that if the connection fails or doesn't complete before the first short lease expires the modem will just reissue the internal IP with another short lease. Something like this?
2005/08/25 11:05:21 GMT E |System |=============== SYSTEM UP ===============
2005/08/25 11:05:21 GMT E |System |Current Mode: PPP on the modem (Public IP for LAN device)
2005/08/25 11:05:22 GMT E |DSL |DataPump Version 01.01.00.00
2005/08/25 11:05:22 GMT E |DSL |State: WAITING
2005/08/25 11:05:24 GMT E |Ethernet |Link 1 Up - 100Base-TX Full Duplex
2005/08/25 11:05:26 GMT E |DSL |State: INITIALIZING
2005/08/25 11:05:34 GMT E |DSL |HYBRID 1
2005/08/25 11:05:34 GMT E |DSL |Link up 1 US 384 DS 1536 (FAST:G.dmt)
2005/08/25 11:06:02 GMT E |DHCP Server |Smarttimeout invoked, lease timeout
2005/08/25 11:06:31 GMT E |DHCP Server |Address 192.168.1.64 given out to 00:09:5b:2c: f2:3b
2005/08/25 11:06:31 GMT E |PPPoE |tx PADI, id: 0000, ac: (NULL), sn: (NULL)
2005/08/25 11:06:31 GMT E |PPPoE |rx AC Name: 62011030047564-rback2.sntc01
2005/08/25 11:06:31 GMT E |PPPoE |tx PADR, id: 0000, ac: (NULL), sn: (NULL)
2005/08/25 11:06:31 GMT E |PPPoE |rx PADS id: C644
2005/08/25 11:06:31 GMT E |PPP |LCP neg PAP
2005/08/25 11:06:31 GMT E |PPP |LCP up
2005/08/25 11:06:33 GMT E |PPP |IPCP nak option: 3
2005/08/25 11:06:33 GMT E |PPP |IPCP nak option: 129
2005/08/25 11:06:33 GMT E |PPP |IPCP nak option: 131
2005/08/25 11:06:33 GMT E |PPP |IPCP up ip: 64.161.28.158,
gw: 64.161.31.254,
dns: 206.13.31.12, 20 6.13.28.12
2005/08/25 11:06:46 GMT E |DHCP Server |Address 64.161.28.158 given out to 00:09:5b:2c :f2:3b
2005/08/25 11:07:10 GMT E |SNTP Client |Updated time from Primary server 132.163.4.102
2005/08/25 11:26:36 GMT E |Ethernet |Link 1 Down
2005/08/25 11:26:37 GMT E |Ethernet |Link 1 Up - 100Base-TX Full Duplex
2005/08/25 12:13:09 GMT E |Ethernet |Link 1 Down
2005/08/25 12:13:11 GMT E |Ethernet |Link 1 Up - 100Base-TX Full Duplex
--
Norman
~A deam, dream, no dream
~Voices of the night go across the forest
~A dream, dream, no dream
~Good night my good child |
