Le 17/12/2010 08:15, Julian Elischer a écrit :
On 12/16/10 10:32 PM, Jayster wrote:
I am in need of immediate help and while I rarely post on boards or
lists (I promise I'll start sharing more of my own wisdom in the
future), this issue has me stumped like no other. First of all, I
need multiple gateways. Yes, I understand there is no such thing as
multiple "default" gateways and I have a solid grasp of networking in
general... . I also have a reasonable grasp of FreeBSD, though I am
no where near the expert of many. I actually come from the world of
programming and I've only used Linux and Windows in the past.
I am currently working on a big project that involves many sites and
a custom appliance with multiple applications designed in-house. In
fact, I might be the ONLY person in snowy Michigan hiring right
now... . After an exhaustive investigation, I chose FreeBSD over all
other OSs. It was not a light choice, but I've been very pleased
despite having zero knowledge at the start of it. The main reasons
were flexibility, licensing and most important, I'm still shocked how
open the community is to answering questions in posts, instead of
putting people down for having less knowledge than a rude poster. I
have found an answer to the most obscure questions through very quick
google searches...until now. Kudos to those who take the
time...FreeBSD far outnumbers other OS communities. Please help me
avoid this issue being the big letdown, possibly forcing us to leave
FreeBSD. I like the OS way too much already.
Now the issue. Without too much detail, my device has 4 GigE ports on
it. Each will be attached to a routed network. There is NO routing
required between networks inside the box (not a router or firewall)
and in fact, it CANNOT be allowed to happen because of security.
Instead, each WAN port needs access to this box, but nothing beyond.
The access consists of a Web Server, though several other Ports are
required, such as SNMP Traps, Syslog, etc. Getting to the box is
easy, routers do all the work. The issue is getting traffic back
through the same interface it came in on and through the same router
gateway. As we all know, only 1 gateway can be assigned in FreeBSD,
unlike other flavors of Linux. Even the ones who don't offer single
line gateway support can use IPTables to accomplish this task. But
IPTables is not supported in FreeBSD. Not a bad thing as long as
comparable solutions exist.
Setting up static routes is not the solution. The problem with it is
that multiple sites which will have this box will not have access to
the next hop info from the gateway (the next hop gateway and subnet
on the other side of the router). So I cannot use static routes.
PFSense appears to support this (though not tested by me). I REALLY
do not want to go that route. We have invested 3 months into adding
many apps to the FreeBSD we have. PFSense is a custom FreeBSD kernel
with many changes. Many message boards claim it breaks many Ports and
changes other behaviors. Even if it didn't, we are under deadline and
moving everything over to a new FreeBSD Version and then extensively
testing everything repeatedly again would be a nightmare. I am
interested in experiences with it if it becomes the last resort, though.
I have tried both PF and IPFW. Different posts around the web claim
Multiple Gateway solutions using both of them. I have tried each of
the recommended setups, but had no luck. If you read the last
responses to each of those posts, others also state they could not
duplicate what is claimed, as well. PF looks the most promising. It
has "if-bound", which is supposed to keep interface traffic on the
same interface. That is a good first step. But pointing it to the
gateway on that interface is still an issue. Please HELP!!! I haven't
slept in days and I've been stuck for a week now!!! This is our last
showstopper.
if you are running on freeBSD 8 or newer you have two solutions open
to you (maybe 3).
* Firstly, you can assign a completely different routing table to each
socket so that
packets from one socket only see things through the perspective of one
routing
table but packets from another socket behave according to the rules of
a completely
different routing table. alternatively you can assign a different
routing table to a
process and its descendants.
you can also use ipfw fwd to remap ports and addresses, in conjunction
with the
different routing tables. Routing tables are sometimes called FIBs
(Forwarding Information Bases)
man setfib(1) and setfib(2) for more details.
Also see the setfib socket option in setsockopt(2).
There are details that are still open for development (like IPV6
support) but
it sounds like it will do what you want.
* The second option is the new jail support.
while setfib and friends can easily allow a single process to act
differently on a socket by socket basis
the new jail facilities allow you to take multiple interfaces and
assign them to different jails,
and each jail can be given a completely different routing table or in
fact a completely different SET of routing tables.
man jail and man ifconfig (ifconfig vnet)
* As a poor third contender you can do really funky things with the
ipfw 'fwd' command.
julian
(let me know offline a bit more about what you want and maybe I can be
a bit more specific about how to do it.)
A third solution that does not involve jails or fib (which to me sounds
like the better approach btw) is to use pf and "route-to" rules such as
this one:
pass out quick on ! bge1 route-to (bge1 ip.of.gateway.on.bge1) from bge1
to any
and repeat for all four network interface.
This should work properly for all TCP based protocols as the source IP
on return packet from your server will be set to the IP of the interface
the trafic came in from. The route-to mechanism will force the gateway
and interface for the return packets based on that knowledge.
I use this on FreeBSD 6 based machines where the new setfib
functionality is not available and that works like a charm.
I don't think any specific kernel option is needed for that. I tried the
forward rules on ipfw, but they were not as easy to setup and not
working reliably in my setup.
Best regards,
Patrick Bihan-Faou
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