[ale] Question on Routes

Mike Harrison cluon at geeklabs.com
Sun Jul 29 05:31:25 EDT 2012


On Sat, 28 Jul 2012, Chuck Payne wrote:

> Guys,
>
> I am going to be switching ISP soons, but until then I am going to run
> two. I have an issue because I don't think I am doing something right.
> I can ping the new ISP, but I can't hit the old one from the outside
> world. I can ping it from the inside,  Here is my network
>
>
> eth0 --> br0 192.168.0.2 network 255.255.255.0  192.168.0.0/24 Internal
> eth1 --> br1 69.176.136.2 netmask 255.255.255.240 69.176.136.0/28 old ISP
> eth2 51.190.58.229. netmask 255.255.255.248 51.190.58.224/29

Once upon a time, I'd fake up such things with insane routing tables.
Then came RIP, OSPF and BGP, but those things are not applicable to a home 
network.

Linux will accept two (or more) default gateways, with weights
and in theory that will solve some of your issues. Others are probably 
beyond your control, as routes and firewalls at a good ISP are designed
to not let you hit them using their IP's from an outside connection.

Just for fun, to make this happen, but not reccomended beyond playing, add 
routes for each ISP's assigned networks blocks to the appropriate upstream
connections:

#whois 69.176.136.2
#
# The following results may also be obtained via:
# 
http://whois.arin.net/rest/nets;q=69.176.136.2?showDetails=true&showARIN=false&ext=netref2
#

NetRange:       69.176.128.0 - 69.176.159.255
CIDR:           69.176.128.0/19


(from memory, not tested, guessing br1?? may be eth??) ie:

route add -net 69.176.128.0 netmask 255.255.224.0 gw 69.176.136.1 br1

This should force the packets going to the local ISP to hit the right 
connection, and go up that stream.

>
> Here is what my routing table looks like.....
>
> route
> Kernel IP routing table
> Destination               Gateway         Genmask                Flags
> Metric Ref    Use Iface
> 51-190-58-224-s            *                  255.255.255.248       U
>   0      0        0 eth2
> 69.176.136.0             69.176.136.1    255.255.255.240       UG    0
>     0        0 br1
> 192.168.105.0               *                 255.255.255.0
> U     0      0        0 br0
> link-local                       *                 255.255.0.0
>     U     0      0        0 eth2
> loopback                       *                 255.0.0.0
>    U     0      0        0 lo
> default                     51-190-58-230-s 0.0.0.0
> UG    0      0        0 eth2



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