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Re: Get to the bottom of what is running my networks

Andrei POPESCU <andreimpopescu@gmail.com> writes:


> Unless ifupdown is smart enough (don't know, you have to research this) 
> the "second" DHCP might override the default gateway of the "first"[1]. 
> Assuming you may want to connect other devices to the OpenWrt you 
> probably don't want to tinker with it's DHCP server and should handle 
> this on the client side. Useful reading:

Andrei suggests:
> man interfaces
> man dhcpclient.conf

What you feared above, did seem to be happening.  But aren't you
supposed to be able to set gateway in /etc/network/interfaces?

`man interfaces' seems to indicate that I could by adding a line like
 gateway xxx.xxx.xxx.xxx

to an interface.


Stealing an idea from Tom H and Bob P, I find even without setting a
gateway, if I add `auto' to the stanzas it seems to come up like I want
it to, and both interfaces can be start/stopped with
/etc/init.d/networking start/stop

/etc/network/interfaces now looks like this: 
  # The loopback network interface
  auto lo
  iface lo inet loopback
  # The primary network interface
  allow-hotplug eth0
  auto eth0
  iface eth0 inet dhcp
  # a secondary network interface
  allow-hotplug eth1
  auto eth1
  iface eth1 inet dhcp
And route -n shows what I wanted to see:

Kernel IP routing table
Destination  Gateway      Genmask         Flags Metric Ref Use Iface         UG    0      0     0 eth0   U     0      0     0 eth0   U     0      0     0 eth1

And it all survives rebooting.

Surprisingly, even when it was coming up with gateway in network, it still seemed to work just fine.  Probably
due to having the pet router hooked up with its wan port facing the
subnet lan, and lan port facing subnet 


> BTW, in a similar situation as yours I decided to connect the OpenWrt 
> device (Asus WL 500gP v2) directly to the gateway via one of the 
> "lan"[2] ports and with a static IP in the same subnet. This way I can 
> use it as just another device on my lan and plan to use it as DNS and 
> web server.

Interesting... I thought about trying that hookup at first, before
going the lan wan route on the test router.  I thought it would be
more like a real setup if I had it as transfer point between and

I expect to throw different stuff at it and watch reactions until I
learn enough about openwrt and iptables to trust my self to run my own
router at the main gateway with wan facing cable modem.

> [2] most devices of this type actually implement the "wan" and "lan" via 
> vlans and it's very under OpenWrt to disable this functionality and use 
> the wan port as just another switch port.

Thanks, and vlans is how this one defaults.

Veering a little off topic here but:

I'm curious when you say you are going to be using embedded openwrt on
a router to run a dns server; Do you mean an honest to god real DNS
server running bind/named (or similar).  I did notice that bind
software is available for recent builds of openwrt.

I don't know about it to hazard a guess myself but I guess you don't
think the small amount of available ram will be a factor in a dns
server or web server of your lans' proportions eh?

That would be a very nice kind of server to have... the size of a
smallish book, quiet, no fans running, not much heat... nice. 

I wonder if you'd know if mine could do the same by these two ouputs:

(TP-Link WR1043ND running very recent openwrt Using: 

-------        ---------       ---=---       ---------      -------- 

/proc/cpuinfo and `free'

system type             : Atheros AR9132 rev 2
machine                 : TP-LINK TL-WR1043ND
processor               : 0
cpu model               : MIPS 24Kc V7.4
BogoMIPS                : 265.42
wait instruction        : yes
microsecond timers      : yes
tlb_entries             : 16
extra interrupt vector  : yes
hardware watchpoint     : yes, count: 4, address/irw mask: [0x0000, 0x0e50, 0x0088, 0x0360]
ASEs implemented        : mips16
shadow register sets    : 1
kscratch registers      : 0
core                    : 0
VCED exceptions         : not available
VCEI exceptions         : not available

-------        ---------       ---=---       ---------      -------- 

             total         used         free       shared      buffers
Mem:         29416        18872        10544            0         1440
-/+ buffers:              17432        11984
Swap:            0            0            0

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