Using Multiple Internet Connections with FreeBSD

Ted Mittelstaedt tedm at toybox.placo.com
Fri Jul 15 06:23:19 GMT 2005


There isn't any such thing unless you speak BGP and minimum cost
of entry on that (at least in the United States) are 2 T1's and
a business justification to consume a minimum of a /20 of address
space, so that you can obtain your own AS #.

The fee on a /20 is about $2,250.00 a year.

Now, if you go to your ISP and get multiple T1's from him you can
do multilink PPP out of the box and aggregate as much as you want.
We have a couple customers we do this with who have 3Mbt links to
us.

No T1s?  Well, if all you want is DSL, then if you get two DSL lines
from your ISP, you might manage something.  He would have to setup to
speak
multilink PPP to you.  It's possible.  If you were a customer of
my employer and willing to drop a couple grand into a Cisco 2600 with 2
ADSL cards in it, I might even be willing configure this on our
side.

You need to think carefully about how networking operates and you
will eventually understand why what you want isn't possible.  (and
no, it's not because us dirty ISP's want to screw you little guys)

The closest you can get is multiple DSL lines to multiple gateways
inside your network, then set half of your machines up to use one
gateway, the other half to use the other.  That will give you more
combined bandwidth, but still any given individual transfer will
be limited to the max speed of the DSL line to the particular gateway
in use.  (exactly the same problem with the ipfw trick below)

I've responded to many of these kinds of posts over the years in
various forums.  Virtually all of them are people who want to get
2 $19.95 a month DSL lines that are classed as residential service,
instead of a single faster DSL line that is classed as business
service and is more expensive.  Rest assured that if such a thing
were possible (which it isn't) every ISP on the planet would take
steps to block it.

Ted

>-----Original Message-----
>From: owner-freebsd-questions at freebsd.org
>[mailto:owner-freebsd-questions at freebsd.org]On Behalf Of John Barbieri
>Sent: Thursday, July 14, 2005 10:20 AM
>To: Philip Hallstrom
>Cc: freebsd-questions at freebsd.org
>Subject: Re: Using Multiple Internet Connections with FreeBSD
>
>
>Thanks for the reply, but this isnt exactly what I was looking for.
>
>This one is used to force packets out to a specific network depending on
>the destination IP address and such.
>
>
>I was looking for something that would allow for both rundunancy and
>speed increase, similar to PPP multi-link or connection teaming (which,
>from what ive read, can effecticly double bandwidth).
>
>Thanks again
>
>John
>
>Philip Hallstrom wrote:
>
>>> To start off, I have a FreeBSD router running Nat and dhcp, it is
>>> currently the router for my LAN.
>>>
>>> I was wondering if there was a way to aggregate more then
>one internet
>>> connection using FreeBSD?
>>>
>>> That is, have 2 or 3 internet connections coming in on seperate NICs,
>>> and being able to have the box route and nat the packets
>accordingly to
>>> the lan, thus giving the experience of more bandwidth. Is it even
>>> possible?
>>>
>>> Has someone done it before? and if you have, do you have a
>webpage that
>>> you followed instructions from?
>>
>>
>> I haven't done it, but I've saved the following email/posts that
>> talked about this...  I've left them intact so you can see
>the context...
>>
>> good luck!
>>
>>> From gerti at bitart.com Wed Dec 24 09:35:16 2003
>>
>> Date: Fri,  3 Nov 2000 18:46:34 -0600
>> From: Gerd Knops <gerti at bitart.com>
>> Reply-To: gerti-freebsdq at bitart.com
>> To: Simon Nielsen <simon at dkik.dk>
>> Cc: questions at FreeBSD.ORG
>> Subject: Re: Two ISP's. Two IP. One default route...
>>
>> Simon Nielsen wrote:
>>
>>> Hello
>>>
>>> I currently have two internet connections though two different ISP's.
>>> One is a ADSL and another is shared with the rest of my dorm. The
>>> shared line is rather slow because many people are using it.
>>>
>>> I must have an IP on the shared connection since that's the only
>>> place where I can be sure to have a non changing IP for my DNS. But
>>> the ADSL is much faster so I would like to use that as much as
>>> possible.
>>>
>>> I can give my machine an IP on each connection but I can of course
>>> only set one default route. The default route is currently set to the
>>> ADSL. The problem is that when a connection is made to IP on the
>>> shared connection my computer uses the ADSL IP to respond and that
>>> does not work.
>>>
>>> Is there a solution to this? I thought about maybe it is possible to
>>> route differently when a connection is made on the shared connection
>>> but I can't find out how to do it.
>>>
>> Yes, it can be done (though I have not found it documented anywhere).
>> I really think there should be separate routing tables for each
>> interface, but I don't know of any such feature in any Unix.
>>
>> However ipfw can be abused for the above task. Assuming:
>>
>>     - ipfw is set to pass on default
>>     - your ADSL IP/network is a.a.a.a/aa
>>     - your shared IP/network is s.s.s.s/ss
>>     - your ADSL gateway is set as default route
>>     - your shared gateway is s.s.s.gw
>>
>> the following ipfw rules do the trick:
>>
>> # Pass anything that should go via normal routes
>> # This rule is really just to speed up the bulk
>> # of the packets
>> add 1000 allow all from a.a.a.a to any
>> # Pass anything to local addresses on ADSL network
>> add 1010 allow all from any to a.a.a.a/aa
>> # Pass anything to local addesses on shared network
>> add 1020 allow all from any to s.s.s.s/ss
>> # And here the trick: if the source address is the one
>> # from the shared network, pass packets to the
>> # gateway on the shared network
>> add 1030 fwd s.s.s.gw all from s.s.s.s to any
>>
>> With the above connections will leave your system on the same route
>> they entered it. Great for redundant mail and dns setup!
>>
>> If you already use ipfw you need to adapt the above rules accordingly.
>> The important part is that packets coming from your host's shared
>> address going to the 'outside' (and only those packets) are forwarded
>> to the shared networks gateway.
>>
>> Gerd
>>
>>
>>> From mwm at mired.org Wed Dec 24 09:35:23 2003
>>
>> Date: Sat, 4 Nov 2000 09:34:48 -0600 (CST)
>> From: Mike Meyer <mwm at mired.org>
>> To: Simon Nielsen <simon at dkik.dk>
>> Cc: questions at FreeBSD.ORG
>> Subject: Re: Two ISP's. Two IP. One default route...
>> Resent-Date: Wed, 24 Dec 2003 10:35:16 -0800 (PST)
>> Resent-From: Philip Hallstrom <philip at alkinetworks.com>
>> Resent-To: Philip Hallstrom <philip at eilio.com>
>> Resent-Subject: Re: Two ISP's. Two IP. One default route...
>>
>> Simon Nielsen <simon at dkik.dk> types:
>>
>>> I currently have two internet connections though two different ISP's.
>>> One is a ADSL and another is shared with the rest of my
>dorm. The shared
>>> line is rather slow because many people are using it.
>>>
>>> I must have an IP on the shared connection since that's the
>only place
>>> where I can be sure to have a non changing IP for my DNS.
>But the ADSL
>>> is much faster so I would like to use that as much as possible.
>>
>>
>> Question: what are you using the static IP for? I.e. - who connects to
>> it, and vice versa?
>>
>>> I can give my machine an IP on each connection but I can of
>course only
>>> set one default route. The default route is currently set to
>the ADSL.
>>> The problem is that when a connection is made to IP on the shared
>>> connection my computer uses the ADSL IP to respond and that does not
>>> work.
>>>
>>> Is there a solution to this? I thought about maybe it is possible to
>>> route differently when a connection is made on the shared
>connection but
>>> I can't find out how to do it.
>>
>>
>> Well, if you can narrow down who connect on the shared connection, you
>> can add a route for those addresses pointing to the shared
>> connection. It's been about five years, but I used to do that, but if
>> the only people connecting to the shared IP are on the campus net, you
>> can add a route that looks like
>>
>>     route add -net campus.net static.ip [campus.netmask]
>>
>>     <mike
>>
>>
>> -------- Original Message --------
>> Subject: two isps routing
>> Date: Wed, 28 Jan 2004 16:38:52 -0800 (PST)
>>
>>
http://www.tldp.org/HOWTO/Adv-Routing-HOWTO/lartc.rpdb.multiple-links.htm
l
>
>
>
>

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