9 Aug
2014
9 Aug
'14
2:29 a.m.
On 2014-08-08 20:55, Eric Fort wrote:
[..]
Occasionally I have access to 2 Verizon DSL
connections in the same
location. the connections while being the same provider are generally a
dynamic IP from different /24 subnets and there's about 4 hops between
them. (once they reach a common point a couple hops away all other
traceroute data is the same. how can I test to see if one connection
filters source addresses belonging to the other?
Depends on your platform. On most OSs just add the IP as a /32 to the
DSL interface.
eg: ip addr add 192.0.2.1/32 dev eth0
and then use it by pinging something.
Then tcpdump on the other interface to see if packets coming back.
If it works, and you want to use it as fail-over, then search for
"Source-based Routing".
(and any guesses as to what the results may be?)
Its Verizon, likely no uRPF enabled at all in that network.
Though there is actually a big chance that by now they have, at least at
their edges.
If you have two lines from the same provider anyway, why not ask them to
support a failover IP/prefix over them?
Greets,
Jeroen