Subject: Authentication of multicast Reconfigure-init messages

From: Ralph Droms <[email-masked]>
Date: Mon, 05 Feb 2001 11:57:03 -0500

I don't know how to authenticate multicast DHCPv6 Reconfigure-init 
messages.  We can use DHCPv4-style authentication - with a separate secret 
key for each client - for unicast Reconfigure-init messages.  However, 
because the multicast Reconfigure-init will be received by multiple 
clients, we can't use a client-specific shared key.  And, if we use a 
single, shared server-specific key, any client configured with the key can 
masquerade as an authorized server.

I would guess we could use a public key encryption mechanism, where the 
authorized servers hold a private key and use it to generate an 
authenticator.  The clients can then authenticate the servers using the 
associated public key.  This scheme would assume that the servers are 
trusted and the private key can be shared among those servers.

Anyone care to jump in and tell me how to use DHCPv4-style authentication, 
flesh out this public key idea or come up with some entirely different 
strategy?

- Ralph

---

From: "Thirumalesh Bhat" <[email-masked]>
Date: Tue, 6 Feb 2001 09:34:28 -0800

We ( Microsoft ) has been looking at this problem. I think a
good solution is one where a client can authenticate the server. This
avoids
a) rogue dhcp servers cropping up in the network. ( intended or by
accident )
b) the client can avoid the problem of getting invalid configuration
info.

	However the problem here is that we want to minimize client
configuration before bootstrap. The question is how can we use DHCP as a
bootstrap protocol without using additional mechanism to configure the
client at boot. May be L-2 authentication protocols can be used in some
way to do this?

thx

-----Original Message-----
From: Ralph Droms [mailto:[email-masked]]
Sent: Monday, February 05, 2001 8:57 AM
To: DHCPv6 discussion list
Cc: [email-masked]
Subject: Authentication of multicast Reconfigure-init messages

I don't know how to authenticate multicast DHCPv6 Reconfigure-init 
messages.  We can use DHCPv4-style authentication - with a separate
secret 
key for each client - for unicast Reconfigure-init messages.  However, 
because the multicast Reconfigure-init will be received by multiple 
clients, we can't use a client-specific shared key.  And, if we use a 
single, shared server-specific key, any client configured with the key
can 
masquerade as an authorized server.

Anyone care to jump in and tell me how to use DHCPv4-style
authentication, 
flesh out this public key idea or come up with some entirely different 
strategy?

- Ralph

---

From: "Bernie Volz (EUD)" <[email-masked]>
Date: Tue, 6 Feb 2001 18:48:53 -0600

Ralph:

Another thought, what about just using IPsec?? It may be punting the problem, but why can't IPsec be used to handle this? The client and server should be able to define the appropriate security association needed (the client can add it when it  has addresses assigned by the server).

The PKI mechanism sounds good as a possibility as well. Wouldn't it simply require a new protocol for the DHCPv4-style authentication option to be defined? I'll leave it to PKI experts to define this.

- Bernie Volz
  Ericsson

-----Original Message-----
From: Ralph Droms [mailto:[email-masked]]
Sent: Monday, February 05, 2001 11:57 AM
To: DHCPv6 discussion list
Cc: [email-masked]
Subject: Authentication of multicast Reconfigure-init messages

- Ralph