[gentoo-user] How to do port-based routing?

[gentoo-user] How to do port-based routing?

[Grant Edwards]

I'm trying to figure out how to do port-based routing.  I found
a HOWTO that does pretty much exactly what I'm trying to do:

http://www.linuxhorizon.ro/iproute2.html

However, it's using iptables, which I thought was deprecated,
but there are iptables versions as recent at three months ago,
so it still seems to be maintained. The above page has
references to the "Linux Advanced Routing & Traffic Control"
site at www.lartc.org, but that site appears to be long-gone.

What's the recommended interface for doing advanced routing
stuff?

-- 
Grant Edwards                   grante             Yow! ... If I had heart
                                  at               failure right now,
                               visi.com            I couldn't be a more
                                                   fortunate man!!

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Re: [gentoo-user] How to do port-based routing?

[Uwe Thiem]

On Monday 03 March 2008, Grant Edwards wrote:
> I'm trying to figure out how to do port-based routing.  I found
> a HOWTO that does pretty much exactly what I'm trying to do:
>
> http://www.linuxhorizon.ro/iproute2.html
>
> However, it's using iptables, which I thought was deprecated,

Not to my knowledge.

Uwe

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Re: [gentoo-user] How to do port-based routing?

[Jason Carson]

> I'm trying to figure out how to do port-based routing.  I found
> a HOWTO that does pretty much exactly what I'm trying to do:
>
> http://www.linuxhorizon.ro/iproute2.html
>
> However, it's using iptables, which I thought was deprecated,
> but there are iptables versions as recent at three months ago,
> so it still seems to be maintained. The above page has
> references to the "Linux Advanced Routing & Traffic Control"
> site at www.lartc.org, but that site appears to be long-gone.
>
> What's the recommended interface for doing advanced routing
> stuff?

There are many interfaces but they are all frontends to iptables.
Personally I just did a lot of reading and built my firewall from scratch.

> --
> Grant Edwards                   grante             Yow! ... If I had heart
>                                   at               failure right now,
>                                visi.com            I couldn't be a more
>                                                    fortunate man!!
>
> --
> gentoo-user@lists.gentoo.org mailing list
>
>


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[gentoo-user] Re: How to do port-based routing?

[Grant Edwards]

On 2008-03-03, Uwe Thiem <uwix@iway.na> wrote:
> On Monday 03 March 2008, Grant Edwards wrote:
>> I'm trying to figure out how to do port-based routing.  I found
>> a HOWTO that does pretty much exactly what I'm trying to do:
>>
>> http://www.linuxhorizon.ro/iproute2.html
>>
>> However, it's using iptables, which I thought was deprecated,
>
> Not to my knowledge.

I would have sworn that one source I found said that ipchains
and iptables were both deprecated in favor of netfilter, but
AFAICT, iptables is the user-space portion of netfilter.

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                                  at               
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Re: [gentoo-user] Re: How to do port-based routing?

[Jason Carson]

> On 2008-03-03, Uwe Thiem <uwix@iway.na> wrote:
>> On Monday 03 March 2008, Grant Edwards wrote:
>>> I'm trying to figure out how to do port-based routing.  I found
>>> a HOWTO that does pretty much exactly what I'm trying to do:
>>>
>>> http://www.linuxhorizon.ro/iproute2.html
>>>
>>> However, it's using iptables, which I thought was deprecated,
>>
>> Not to my knowledge.
>
> I would have sworn that one source I found said that ipchains
> and iptables were both deprecated in favor of netfilter, but
> AFAICT, iptables is the user-space portion of netfilter.
>
> --
> Grant Edwards                   grante             Yow! I Know A Joke!!
>                                   at
>                                visi.com
>
> --
> gentoo-user@lists.gentoo.org mailing list
>
>
ipchains is used in the 2.2 kernel. iptables is for the 2.4 and 2.6
kernels. From the netfilter website "Software commonly associated with
netfilter.org is iptables."

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Re: [gentoo-user] Re: How to do port-based routing?

[Arturo 'Buanzo' Busleiman]

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Grant Edwards wrote:
| AFAICT, iptables is the user-space portion of netfilter.

That's correct, yes.

- --
Arturo "Buanzo" Busleiman
Reliable inter-continental Mail Relay Service - Ask me!
Independent Security Consultant - SANS - OISSG
http://www.buanzo.com.ar/pro/
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[gentoo-user] Re: How to do port-based routing?

[Grant Edwards]

On 2008-03-03, Jason Carson <jay@canuckster.org> wrote:
>> I'm trying to figure out how to do port-based routing.  I found
>> a HOWTO that does pretty much exactly what I'm trying to do:
>>
>> http://www.linuxhorizon.ro/iproute2.html
>>
>> However, it's using iptables, which I thought was deprecated,
>> but there are iptables versions as recent at three months ago,
>> so it still seems to be maintained. The above page has
>> references to the "Linux Advanced Routing & Traffic Control"
>> site at www.lartc.org, but that site appears to be long-gone.
>>
>> What's the recommended interface for doing advanced routing
>> stuff?
>
> There are many interfaces but they are all frontends to
> iptables. Personally I just did a lot of reading and built my
> firewall from scratch.

I found shorewall and firestarter, but neither looked very
useful to me:

 1) They're both designed for configuring firewalls, and I'm
    not building a firewall machine.

 2) Neither seemed to have any way to specify port-based routing.

So it looks like plain iptables is the way to go.

-- 
Grant Edwards                   grante             Yow! I want another
                                  at               RE-WRITE on my CEASAR
                               visi.com            SALAD!!

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Re: [gentoo-user] Re: How to do port-based routing?

[Dan Cowsill]

On Mon, Mar 3, 2008 at 2:36 PM, Grant Edwards <grante@visi.com> wrote:
> On 2008-03-03, Jason Carson <jay@canuckster.org> wrote:
>  >> I'm trying to figure out how to do port-based routing.  I found
>  >> a HOWTO that does pretty much exactly what I'm trying to do:
>  >>
>  >> http://www.linuxhorizon.ro/iproute2.html
>  >>
>  >> However, it's using iptables, which I thought was deprecated,
>  >> but there are iptables versions as recent at three months ago,
>  >> so it still seems to be maintained. The above page has
>  >> references to the "Linux Advanced Routing & Traffic Control"
>  >> site at www.lartc.org, but that site appears to be long-gone.
>  >>
>  >> What's the recommended interface for doing advanced routing
>  >> stuff?
>  >
>  > There are many interfaces but they are all frontends to
>  > iptables. Personally I just did a lot of reading and built my
>  > firewall from scratch.
>
>  I found shorewall and firestarter, but neither looked very
>  useful to me:
>
>   1) They're both designed for configuring firewalls, and I'm
>     not building a firewall machine.
>
>   2) Neither seemed to have any way to specify port-based routing.
>
>  So it looks like plain iptables is the way to go.
>
>  --
>  Grant Edwards                   grante             Yow! I want another
>                                   at               RE-WRITE on my CEASAR
>                                visi.com            SALAD!!
>
>  --
>
>
> gentoo-user@lists.gentoo.org mailing list
>
>

I hate to plug a non-gentoo distro, but if you're building yourself a
linux firewall and you want to do so without rtfm'ing, smoothwall is
the way to go.

-- 
Dan Cowsill
http://www.danthehat.net
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Re: [gentoo-user] Re: How to do port-based routing?

[kashani]

Grant Edwards wrote:
> I found shorewall and firestarter, but neither looked very
> useful to me:
> 
>  1) They're both designed for configuring firewalls, and I'm
>     not building a firewall machine.
> 
>  2) Neither seemed to have any way to specify port-based routing.
> 
> So it looks like plain iptables is the way to go.
> 

	I'm not aware of any iptables front end that will also manager policy 
based routing which is Cisco-ese and maybe general Network-ese for what 
you're trying to do. However I would use shorewall (or whatever you 
prefer) to do most of the work and then insert your custom rules where 
they need to go.
	All policy routing regardless of actual implementation has you build an 
ACL of traffic you'd like messed with. Then you need to specify what 
happens to traffic that matches the ACL. However one thing the original 
how-to you linked left didn't completely spell out is NAT. You MUST NAT 
on each interface or you'll have all sorts of routing fun that does not 
work.

kashani
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[gentoo-user] Re: How to do port-based routing?

[Grant Edwards]

On 2008-03-03, Dan Cowsill <danthehat@gmail.com> wrote:

>>  I found shorewall and firestarter, but neither looked very
>>  useful to me:
>>
>>   1) [...] I'm not building a firewall machine.

> I hate to plug a non-gentoo distro, but if you're building
> yourself a linux firewall and you want to do so without
> rtfm'ing, smoothwall is the way to go.

-- 
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                                  at               apartment entirely in ten
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[gentoo-user] Re: How to do port-based routing?

[Grant Edwards]

On 2008-03-03, kashani <kashani-list@badapple.net> wrote:

> I'm not aware of any iptables front end that will also manager
> policy based routing which is Cisco-ese and maybe general
> Network-ese for what you're trying to do. However I would use
> shorewall (or whatever you prefer) to do most of the work and
> then insert your custom rules where they need to go.

AFAICT, I only need to add 1 iptable rule to mark outbound
frames destined to particular ports.

> All policy routing regardless of actual implementation has you
> build an ACL of traffic you'd like messed with. Then you need
> to specify what happens to traffic that matches the ACL.
> However one thing the original how-to you linked left didn't
> completely spell out is NAT. You MUST NAT on each interface or
> you'll have all sorts of routing fun that does not work.

I don't understand why I have to do NAT.  Can you explain why?
(Or point me to docs that explain why?)

-- 
Grant Edwards                   grante             Yow!
                                  at               BI-BI-BI-BI-BI-BI-BI-BI-BI-BI-BI-BI-BI-BI-BI-BI-BI-BI-BI-BI-BI-BI-BI-BI-
                               visi.com            

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[gentoo-user] Re: How to do port-based routing?

[Grant Edwards]

On 2008-03-03, Grant Edwards <grante@visi.com> wrote:
> On 2008-03-03, kashani <kashani-list@badapple.net> wrote:
>
>> I'm not aware of any iptables front end that will also manager
>> policy based routing which is Cisco-ese and maybe general
>> Network-ese for what you're trying to do. However I would use
>> shorewall (or whatever you prefer) to do most of the work and
>> then insert your custom rules where they need to go.
>
> AFAICT, I only need to add 1 iptable rule to mark outbound
> frames destined to particular ports.
>
>> All policy routing regardless of actual implementation has you
>> build an ACL of traffic you'd like messed with. Then you need
>> to specify what happens to traffic that matches the ACL.
>> However one thing the original how-to you linked left didn't
>> completely spell out is NAT. You MUST NAT on each interface or
>> you'll have all sorts of routing fun that does not work.
>
> I don't understand why I have to do NAT.  Can you explain why?
> (Or point me to docs that explain why?)

OK, I think I see what you mean.  The in the HOWTO to which I
linked, the box in question is apparently routing between an
internal network on eth0 and two external gateways on eth1 and
eth2.  It is choosing the external gateway based on the
destination port of the outbound packet.  That's obviously only
make sense if it's also doing NAT.

My application is not routing for any other machines/networks.
It's just a desktop machine belonging to an end-user.  It has
two gateways to "the Internet" (each of those gateways is doing
NAT).  All I want to do is select a gateway based on the
destination port of outbound packets.

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Re: [gentoo-user] Re: How to do port-based routing?

[kashani]

Grant Edwards wrote:

> I don't understand why I have to do NAT.  Can you explain why?
> (Or point me to docs that explain why?)
> 

router01.your.network.com
	eth0 - 10.11.12.1
	eth1 - 24.1.2.231 - Comcast
	eth2 - 64.1.2.132 - Speakeasy

Naturally RFC 1918 space is useless outside your network so you have to 
NAT. However you need to make sure that you are making your policy 
routing decisions at eth0. You don't want traffic marked as originating 
from 24.1.2.231 going out eth2 since Speakeasy could (and should) drop 
traffic that is not origination from its IP space. Additionally traffic 
will be routing back to your via Comcast connection resulting in 
asymmetric routing which can increase the chances of packets arriving 
out of order.

router01.your.network.com
	eth0 - 24.2.3.1/29
	eth0 - 64.2.3.1/29
	eth1 - 24.1.2.231 - Comcast
	eth2 - 64.1.2.132 - Speakeasy

Same case with this setup even with real IPs. The chances of convincing 
any ISP to accept routes smaller than /24 from you are tiny. And finding 
anyone who knows what you even want to do even when you have the IP 
space is pretty much non-existent. I know, I've tried. Same thing in 
this case, you'll NAT at eth1 and eth2 and policy router at eth0.

If you are doing this from a single machine with two IP's and no other 
networks or interfaces, it should just work. Linux should use the IP of 
interface the packet leaves from, but I'd use tcpdump to make sure.

kashani
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[gentoo-user] Re: How to do port-based routing?

[Grant Edwards]

On 2008-03-03, kashani <kashani-list@badapple.net> wrote:
> Grant Edwards wrote:
>
>> I don't understand why I have to do NAT.  Can you explain why?
>> (Or point me to docs that explain why?)
>
> router01.your.network.com
> 	eth0 - 10.11.12.1
> 	eth1 - 24.1.2.231 - Comcast
> 	eth2 - 64.1.2.132 - Speakeasy
>
> Naturally RFC 1918 space is useless outside your network so
> you have to NAT.

Both of my gateways are on local networks and are doing NAT.

> However you need to make sure that you are making your policy 
> routing decisions at eth0. You don't want traffic marked as
> originating from 24.1.2.231 going out eth2

I don't have IP forwarding enabled, so that shouldn't happen.

> since Speakeasy could (and should) drop traffic that is not
> origination from its IP space. Additionally traffic will be
> routing back to your via Comcast connection resulting in 
> asymmetric routing which can increase the chances of packets
> arriving out of order.
>
> router01.your.network.com
> 	eth0 - 24.2.3.1/29
> 	eth0 - 64.2.3.1/29
> 	eth1 - 24.1.2.231 - Comcast
> 	eth2 - 64.1.2.132 - Speakeasy
>
> Same case with this setup even with real IPs. The chances of convincing 
> any ISP to accept routes smaller than /24 from you are tiny. And finding 
> anyone who knows what you even want to do even when you have the IP 
> space is pretty much non-existent. I know, I've tried. Same thing in 
> this case, you'll NAT at eth1 and eth2 and policy router at eth0.
>
> If you are doing this from a single machine with two IP's and no other 
> networks or interfaces, it should just work.

The machine will have different non-routing IPs on the two
interfaces where the two NAT/firewall/gateways are.  The
machine does have interfaces/networks, but since I'm not
forwarding packets, they should be irrelevant.

> Linux should use the IP of interface the packet leaves from,
> but I'd use tcpdump to make sure.

Good idea.

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Re: [gentoo-user] How to do port-based routing?

[Dan Farrell]

On Mon, 3 Mar 2008 14:11:20 -0500 (EST)
"Jason Carson" <jay@canuckster.org> wrote:

> There are many interfaces but they are all frontends to iptables.
> Personally I just did a lot of reading and built my firewall from
> scratch.

that's the spirit ; )
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Re: [gentoo-user] How to do port-based routing?

[Mark David Dumlao]

[-- Attachment #1: Type: text/plain, Size: 270 bytes --]

to be accurate, Netfilter is the internal name of the Linux subsystem that
plays
around with packets.

ipchains and iptables are specific implementations of Netfilter.  They also
just
happen to be the names of the programs that edit Netfilter rules as well.

-- 
thing.

[-- Attachment #2: Type: text/html, Size: 309 bytes --]