Graham J <graham@invalid> wrote
Many thanks for your comments everyone.
>
>Curious.
>
>I've used all versions of Vigor routers since the 2600 and never had any
>problems with setting up a VPN and getting reliable operation.
>
>But:
>
>1) Ideally, you must have a static IP address at both ends of the VPN.
>Exceptions to this require some manual intervention.
Have that.
>2) Configure the routers so you have remote management. You must have a
>static IP address at your management location to achieve this.
The routers have external admin ports but they are disabled. One can
access the router config only from one of the PCs on the internal LAN;
I am happy with that.
Oddly enough, the 2900 still responds to port 443 packets on its admin
port, even when remote management is disabled, facilitating dictionary
attacks (which get nowhere but "somebody" out there keeps running
them)

One way around this we found is to port-forward port 443
packets to an internal IP which has nothing listening on it. Draytek
never fixed this, despite it having been reported.
>If ADSL sync fails or the PPP session gets stuck you will have to
>manually reboot the remote router; but I've only seen this where
>lightning strikes cause the local mains to twitch. But it has happened
>with every ISP I've used and every router I've used, so in your
>application this is why you need the SMS power resetter. Even that
>isn't reliable - no phone operator I've talked to will guarantee the
>(timely) delivery of an SMS message. Is it in fact the lack of internet
>connection that causes your VPN to fail? You must distinguish between
>the two.
I am aware that if the ADSL is interrupted then the router may need
resetting, and that alone is a good reason for the SMS-triggered
remote power cycle facility, but I am sure this is not the cause of
the vast majority of the very regular router crashes during VPN usage.
>3) Where possible I use the LAN-to-LAN option. Depending on the
>application I might use dial-in/dial-out or both call directions. IPSec
>tunnel only; this forces the IKE Pre-shared key. Security method =
>High(ESP), AES with Authentication. I specify the remote network IP
>range + mask and the local network IP (the local router itself) and
>mask. RIP off. Route to remote subnet.
I think this is what I have, though the config was opaque to me.
>The VPN can be brought up by any network traffic for an IP address at
>the other end. Where I want the VPN to be nailed-up I set it one-way
>only and add the "always on" and "ping to keepalive" setting.
The VPN sets up in a few secs so I am not keeping it alive.
>4) Given that I have a static address, if I have to connect to a client
>with a dynamic address I set my router to dial-out only and equip the
>remote client with a DDNS setting. At the client end his router is
>configured as dial-in only. It follows that I can bring up the VPN but
>he cannot.
>
>You cannot make a LAN-to-LAN VPN if both ends have dynamic addresses.
>
>The problem with this is that quite often network traffic is not enough
>to bring up the VPN. I find it necessary to open a browser on the
>management of the remote router - this is sufficient, don't even have to
>log in - ping something on the remote network - then close the browser.
>
>The LAN-to-LAN VPN is very sensitive to the transit time from one site
>to another. If the ADSL or cable service is very congested the VPN will
>drop. Changing to a professional ISP usually resolves this.
Interesting. I wonder if that's it. One is Eclipse and the other is
ZEN. ZEN is the better of the two but I can't have the same ISP for
both locations. But both ADSL services come off the same (rural)
exchange; the sites are only 2 miles apart.
>------------
>
>I tried these settings with a satellite link (ping times over half a
>second!) - total failure. However - use PPTP (simple username &
>password, VJ compression, set remote site to dial-out and my management
>site for dial-in, configure as always-on. If the satellite connection
>fails (which it does, far more frequently than you would blame on power
>failures at the remote site - a quarry in the middle of nowhere) the
>remote router reconnects to mine as soon as the satellite link comes up.
>
>Using this VPN is a different matter - it does require real patience -
>but it saves a 50-mile trip to the site!
>
>The DDNS presents a problem - the satallite IP address doesn't actually
>change, but the supplier says it is dynamic. So the DDNS supplier sends
>reqular emails warning that the service hasn't been used, which have to
>be responded to. Paying for a DDNS service would solve that.
>
>------------
>
>These LAN-to-LAN VPNs work from any model of Vigor router to any other,
>provided that they have the current firmware.
>
>When setting up a new VPN I have sometimes found it necessary to reboot
>one or other router - not often enough to form a view as to which
>actually resolves the problem.
>
>If I can get a management connection to the router I can always get the
>VPN up - even where the VPN is between sites A and B and I am at site C
>- but as above, if the address (of A or B) is resolved through DDNS then
>it may be necessary at C to open a browser on either router A or router B.
>
>------------
>
>How are your routers connected to the internet? You mentioned 3G/GPRS -
>in my experience this won't work with IPSec, but (as with my satellite
>link) might work with PPTP. There are 3G services which assign static
>IP addresses.
One has a D-link something-300 modem (now quite old but once very
popular) and the other has a Draytek Vigor 120, but used to have a
D-link before that.
I am not using 3G fallback at all at present.
>My remote management is done either with VNC or Remote Desktop - or
>simply with a browser where the remote device is a printer or the like
>with a web management page. Telnet will also work - the beauty of the
>LAN-to-LAN configuration is that it connects your LAN to the remote LAN,
>so anything that would work locally will work to the remote site. All
>devices must have the router set as the default gateway.
>
>A Windows PC at one site connected to a Windows Domain Controller at
>another site must have its DNS pointed to the DC. This is a potential
>performance bottleneck and I haven't found a good solution to it ....
>
>The remote LAN's IP address must of course be different to your local
>one; and most older Vigor routers only support 32 concurrent LAN-LAN
>profiles. I'm running out ....
I think none of this is an issue, but the VPN crashing (and the WIFI
crashing with Apple clients) remain.
Good point in another post about using a separate WIFI AP... I have a
WRT54GC at home, used this way. One can also set up port range
blocking in that, and blocking ports 138 etc stops windoze networking
working which can be very handy because visitors can use the WIFI but
can't even see your PCs.