Re: Policy routing (fwmark-based) and local traffic...

On 7/31/19 3:10 AM, Marco Gaiarin wrote:
> Ok. I manage some gateway that handle two or more connection to ISP; 
> i balance traffic between routes, and sometimes via policy routing i 
> 'bind' some traffic to some interfaces (forward traffic, so PREROUTING 
> in mangle).

Thank you for the high level.  I figured that was the case, but I wanted 
to ask to be sure.

> This time i needed to bind local generated traffic, because one of 
> the two line use dynamic IP and the service i use need static IP 
> (they have some ACLs).

That makes perfect sense.

I do wonder if a static route via the ISP connection with the static IP 
might suffice.  (Which it sounds like you might now be doing that.)

> Initially i've simply applied the same policy i was used to, but 
> does not work (clearly, PREROUTING is for forwarded traffic, not or 
> local generated one! Stupid me! ;).  Then i've tried with OUTPUT, 
> but with the same result.
> 
> Now i'm using explicit routing, and clearly works. But i was curious, 
> so i've posted here.

*nod*

> Do you mean this?
> 	https://netdevconf.org/1.2/papers/ahern-what-is-l3mdev-paper.pdf

Yes.

> I've no kernel 4.4, but i'm using load balancing with:
> 	https://www.tldp.org/HOWTO/Adv-Routing-HOWTO/lartc.rpdb.multiple-links.html
> 
> and i suppose is a similar concept...

Yes.

I think l3mdev takes that concept and extends it such that you don't 
need to worry about rules / fwmarks / etc.  Instead, the l3mdev plumbing 
takes care of choosing what routing table is used automatically.



-- 
Grant. . . .
unix || die