[nos-bbs] HTTP server restriction maybe

(Skip) K8RRA k8rra at ameritech.net
Wed Apr 18 21:27:08 EDT 2007

I hate to do this Jay, but the formula does not work here...

On Tue, 2007-04-17 at 15:03 -0400, Jay Nugent wrote:

> Greetings Skip (et al),
> On Tue, 17 Apr 2007, (Skip) K8RRA wrote:
> > On Tue, 2007-04-17 at 12:08 -0500, Barry Siegfried wrote:

>    Nada.  No way.  Uh uh. No sirie!  NAT, cough gag hurl!
>    The "source" address of an outgoing packet is determined by the
> *interface* address used.  And which *interface* is determined by the
> destination address you are trying to reach, and what *interface* the
> *route table* says you must use to get to the desired destination.

The above protocol did not work here - the FROM IP remained 192... as
seen in the tun0 trace.
I used ping (me) and (Dave)
In all cases the ICMP packet from ping did go out the radio as it should
- OUTBOUND is OK... except for FROM IP.
The route table is attached for your inspection.

>    That's alot to chew on.  Let me explain...
>    I have a Linux box here.  It's address is

I have a Linux box here with FC-6 and jnos on it.  The host is static

>   However, I 
> would like this box to also be able to reach the HTTP webpages at 
> wb8rcr.ampr.org.  To do this I added an additional *interface* to this box 
> along with the supporting *route* entry, as follows:
>    ifconfig eth0:44
>    route add -net gw

My choices were both:

    ifconfig eth0:44
    route add -net  tun0


   ifconfig tun0:44
   route add -net tun0

In both cases the ifconfig showed the desired added interface - I don't
have yours for comparison but they look OK to me.

Interesting fact (FYI):
In the first case "eth0:44" the ifconfig statement added a route to the
host table " * ... eth0"
In the second case "tun0:44" there was no route added to the table

>    So at this point I now have a Linux box that will send ALL it's traffic
> out onto my ethernet as *UNLESS* it happens to be going to
> anything in the AMPRnet (44/8).  In which case it flows out onto my
> ethernet addressesd FROM and GATEWAYED through
> (which happens to be my JNOS/Hamgate on that very same ethernet).
>    Now, remember what I said about "Think like a Packet" the other day.  
> What's missing?  ...a return route!!!
>    So on the JNOS/Hamgate I have to add a route that will send any packets
> it receives *for* *back* to the Linux box on the ethernet.  
> So on the JNOS/Hamgate I have added this route:
>    route add eth0

this was:
   route add tun0

The route tables partly worked - the packet went out.

>    BINGO!!!  

NO BINGO!!!  Lost packets for wrong FROM IP (I guess).

>    Skip, I believe you will be attending this Saturday's DRG meeting?  In
> my training session I'll be going over static routing and how to "Think
> like a Packet".  Hope to see you there!  And hope that we can help clear
> up any misconceptions and help lift the fog a little.  I'll bring an empty
> V8 juice can with me so you can smack it into your forehead when this all
> comes clear for you ;-)  See you there!

I expect you will see me - but I'd like to be successful before I arrive
at the meeting.

What say you?

>       --- Jay Nugent  WB8TKL

de [George (Skip) VerDuin] K8RRA k
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Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
k8rra.ampr.org  *      UH    0      0        0 tun0     *        U     0      0        0 eth0     *          U     0      0        0 eth0      *          U     0      0        0 tun0
default         UG    0      0        0 eth0

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