VOIP with a linksys PAP2

[THUFIR HAWAT]

On 6/13/05, Kevin J. Cummings <cummings at kjchome.homeip.net> wrote:
> THUFIR HAWAT wrote:
> > On 6/12/05, Kevin J. Cummings <cummings at kjchome.homeip.net> wrote:
> > ...
> >
> >>Your internet connection is WI-FI????  Is this a Linksys router with
> >>WI-FI?  Is it configured to route multiple network traffic or just your
> >>linux machine?  Does it know about the "network" on your Linux machine's
> >>eth1?
> >
> >
> > the internet connection is from
> > <http://usa.asus.com/products/communication/wireless/wl-330g/overview.htm>
> > into eth0 and a hub is plugged into eth1, then a linksys PAP2
> > <http://www.linksys.com/products/product.asp?prid=651&scid=38> into the
> > hub.
> 
> OK, I assume that the WL330g is a wireless access point that connects to
> a local wireless router through which your Linux box can connect to the
> internet.  I'll also assume that it connectes to an ethernet card in
> your computer which is eth0.  Further, I'll assume that this connection
> is working fine.
> 
> You probably have a routing table (ip route or route) which looks
> something like:
> 
> 192.168.1.0/24 dev eth0  proto kernel  scope link  src 192.168.1.1
> default via 192.168.1.2 dev eth0
> 
> (the actual number might be different for you depending on your network)
> 
> > I think all I need is the masquerading..?  but, I'd first like to test
> > the hardware with pings, or something.
> 
> In order to ping the PAP2 from Linux, both need to have their network
> interfaces properly configured.  They need to be on the same "subnet",
> and your routing table needs to be able to send the packets over the
> correct ethernet device (eth1).  Once you know what the IP addresses
> are, you can use them to "ping" the devices.  If you don;t have the
> properly configured, you can't ping.
> 
> >>If PAP2 is plugged into a HUB, then you don't need a crossover cable,
> >>you want a straight through.  Is your HUB a router, a switch, or a
> >>bridge?  A switch doesn't need configuring, a router may.
> >
> >
> > according to the box:
> >
> > wisecom 8 port 10 base-T hub
> >
> > compliant with 10base-t, 10BASE2 and 10BASE5 specifications of the
> > IEEE 802.3 standard.
> 
> This is a standard 10base-t 8 port hub with 3 different upload ports,
> which you probably don't need to use.  It cares not about the network it
> is plugged into.  Any packets which arrive through 1 of the 8 ports will
> be re-transmitted out the other 7 (and the active upload port if its in
> use).  If you only have your computer and the PAP2 plugged into it, then
> the 2 should be able to talk to each other through the port.
> 
> > and, it's an ethernet HUB for WorkGroup
> >
> > I think it's a switch, definitely not a router.
> 
> No, a switch can handle multiple speeds and "remembers" which ports
> certain devices are attached to (via their MAC addresses) and only
> transmits the incoming packets out to the one destination port.
> Switches cost more than plain hubs.
> 
> >>How is the telephone plugged into a hub?   Ethernet hubs don't (usually)
> >>have POTS (analog telephone) jacks.  I would think that your telephone
> >>should be plugged into something which is not a network or ethernet
> >>router, but some kind of telephony equipment.  (Isn't that what your
> >>PAP2 is?)
> 
> According to the PAP2 documentation I looked at, it has 2 telephone
> ports.  You should plug your telephones into the PAP2.
> 
> > the PAP2 is plugged into the hub. the hub is plugged into eth1.
> 
> OK, that's good.
> 
> >>>on boot I got a message about lost packets, but it went by too fast.
> >>>I've installed firestarter.  I need to set up dhcp, perhaps.  how do I
> >>>ping, or ipconfig the hub?
> >>
> >>Have you checked your log files (/var/log/messages)?  used the "dmesg"
> >>command to see your boot-up messages?  Just because you didn't read them
> >>on the screen doesn't necessarily mean they are gone forever!
> >
> >
> > I'll check /var/log/messages, thanks.
> 
> I saw your boot messages, it looks like eth1 is being configured via
> DHCP as 198.162.2.1  and your eth0 configuration is failing to start?
> Are you sure you have them correctly identified?  What does "route" give
> you for output?  One of your interfaces is acting like there is no cable
> plugged into it....  What does "route" tell you?  Where does your
> "default" route go?
> 
> >
> >>Does your Linux box have IP forwarding configured?  Is the eth1 metwork
> >>publicly routable?  If not, have you configured Linux to do NATing?
> >
> >
> > this I haven't yet done.
> 
> Then your PAP2 won't be able to find its VOIP service until you do this.
> Using NAT will allow your Linux computer to masquarade the TCP/IP
> packets out to the internet and back to the PAP2 for you.  You'll also
> need to make sure that IP forwarding is turned on.  Without it, Linux
> won't even try to route the packets from eth1 to eth0 and vice versa.
> 
> >>How does your PAP2 get its IP address?  If you don't know, you probably
> >>need to configure a DHCP server on Linux as well!  Is there anything
> >>else on the eth1 network (ie, is anything else plugged into your hub)?
> >>If so, how are they allocated IP addresses?
> >
> >
> > the hub just has two connections.  one to the computer, one to the
> > PAP2.  I need to find out how the allocate IP addresses.
> >
> >>This is all *basic* network configuration....
> >>
> >
> >
> > I know it's basic, but it's not something I know about yet.
> 
> Its pretty simple once you understand it.  B^)
> 
> INET (via WIFI) <-> wl-330g <-> eth0 [linux] eth1 <-> hub <-> PAP2
> 
> eth0 needs an IP ADDRESS, NETMASK, and BROADCAST address in order to
> talk with the wl-330g which must somehow must communicate with your
> wireless INET connection.  It would not surprise me to find out the the
> wl-330g provides a DHCP/NATed subnet to eth0.  eth1 will require the
> same, though its possible they are being handled via DHCP from the PAP2.
>   You will probably need to make saure that the 2 ethernet networks are
> on different subnets for ease in routing (and NATing) and so that the
> wl-330g doesn't have to know anything about the network connection of
> eth1.  You can use "unroutable" IP address ranges locally for your
> internal private networks and handle the allocation of those addresses
> by yourself.
> 
> Looks like you're going to be having a lot of fun getting this to work!
> Enjoy!
> 
> --
> Kevin J. Cummings
> kjchome at rcn.com
> cummings at kjchome.homeip.net
> cummings at kjc386.framingham.ma.us
> 
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everything above makes sense and is correct.

-Thufir