RE: UDP port 500 traffic from two clients

From: Greg A. Woods (
Date: 01/29/02

From: (Greg A. Woods)
To: "Fernando Cardoso" <>
Date: Tue, 29 Jan 2002 12:47:43 -0500 (EST)

[ On Tuesday, January 29, 2002 at 09:48:56 (-0000), Fernando Cardoso wrote: ]
> Subject: RE: UDP port 500 traffic from two clients
> Just a small note on this: you can use IPSec for remote administration of
> servers with the same degree of confidence you'd use SSH. I do understand
> and agree with Greg's concerns about trusting everything on the remote
> network, but you're thinking of IPSec only in terms of tunelling, where you
> have a couple of gateways (peers) doing encryption and decryption on behalf
> of other hosts.

I thought I had explained clearly enough in my post that most
implementations of VPNs using IPSec for this purpose will be of the form
where the remote user is connecting his host to a network via a gateway.

> If you use IPSec in transport mode, you'll have end-to-end
> encryption between two hosts, which is equivalent to what you'd achieve with
> SSH.

That implies that the remote administrator has prepared for the ability
to run IPSec on every host that might be managed from a remote location.
This is very often not true, and sometimes not even possible (such as
with a console terminal server that might be used to reboot a remote
server, etc.).

I wanted to re-iterate this fact because I also wanted to mention that
system managers should probably be using SSH (or maybe if they want and
they can, IPSec in transport mode with every managed server)
consistently even when they are working from a host directly attached to
the private network, and for the very same reasons (which primarily are
of course that with most security incidents originating as "inside
jobs", your greatest threats are probably already legitimately on your
private nework!).

								Greg A. Woods

+1 416 218-0098; <>; <>; <> Planix, Inc. <>; VE3TCP; Secrets of the Weird <>

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