Firewall Wizards mailing list archives

Re: VPN concentrators


From: Patrick Darden <darden () armc org>
Date: Tue, 27 Aug 2002 08:05:40 -0400 (EDT)


So, you have traffic coming thru your bastion router, hitting your
firewall, and if vpn traffic then routed to the vpn engine, then routed
back to the firewall on another interface, then into your internal
network.  Have you made this work?  Where is your second vpn switch for
redundancy and failover?  How does vrrp/whatever work?  Frankly, it looks
unwieldy--but you can't argue with success.  I'd be interested in more
details.

--
--Patrick Darden                Internetworking Manager             
--                              706.475.3312    darden () armc org
--                              Athens Regional Medical Center


On Tue, 27 Aug 2002 scouser () paradise net nz wrote:

Actually I was thinking more along these lines.(trying to keep the box count
down, to reduce management overhead)

Internet connection
      |
 -----|-----
 bastionrouter
 -------------
  |        
 firewall ---- vpn engine
  |   |___________|         
  |       
  | 
  |
  |
 --------------------
 internal network


I do not trust incoming traffic. I do not trust the X hundred VPN users to
secure there endpoints from trojans, malware etc... So I want to be able to
inspect and filter traffic after it leaves the tunnel and before it enters my
network.
It is also nice to beable to inspect the traffic more than once, ie run some
NIDS on the traffic (before it has entered the network).
I have yet to find a single product that does both to a satisfactory level of
assurance.

James
Quoting Patrick Darden <darden () armc org>:


I think the original poster's idea was (just to be clear):

 ds3
 |
-----|-----
bastionrouter
-------------
 | |
firewall vpn engine
 | |
 | |
 | firewall
 | |
 | |
-----------------------
internal network


In my original diagram, DOS attacks would be filtered at the bastion
router. In this diagram, after the vpn engine receives and verifies and
confirms packets, then they are routed through a firewall.... Redundant
and useless. Let's say it is a top of the line content-inspecting,
state-keeping, packet filtering firewall--how is that better than the
vpn
engine which does all of this and more? The vpn engine verifies and
confirms and filters based on the sip, dip, state, and packet contents;
and can do this on a per-user or per-group basis, thus giving different
users different "levels" of access.

Having this extra firewall is not useful.

--
--Patrick Darden Internetworking Manager 
-- 706.475.3312 darden () armc org
-- Athens Regional Medical Center


On Mon, 26 Aug 2002, m p wrote:

--- Patrick Darden <darden () armc org> schrieb: > 
I don't agree. Putting authenticated and authorized traffic through
a
firewall is redundant. IPSEC traffic is trusted traffic. A VPN is
an
extension of your network--it is as trusted as any traffic internal
to
your network--perhaps more, as it can be completely accounted
for--remember that every packet has a confirmed sip, dip, and
payload.


I beg to differ.

He talked about VPN - not authorized and authenticated traffic from a
source he can trust 100%.

Traffic via a VPN can be from different sources with different levels
of trust. It can be a company or an employee or a branch office. That
are 3 classes of different trustworthy. Perhaps there are more.

There were some DoS-attacks against the Windows IPSEC implementation
last year. There too was a DoS attack against some open source IPSEC
implementation. If you can limit the addresses that connect to the
termination point of your VPN it may be worth the additional layer of
security.

To make sure each person that logins / operate via the VPN is only
allowed to see what he/she/it should see there should be a firewall
behind the termination point of the VPN.

Yes, traffic via VPN should be the same as normal "in-house" traffic.
But the connection begin can be a problem - and if traffic via VPN is
not "in-house" traffic. If you firewall the RAS users in your company
you should too firewall the VPN users.

Just my 2 euro cent

Marc


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