ip masquerading

Sun Nov 25 21:10:51 UTC 2007

bruce wrote:
> again.. hi john..
> 
> if by network mangler, you mean "network manager", no, it's not enabled on
> the laptop/system.
Well, it's not going to support this configuration. What do you think?
> 
> i've tried various route cmds, but it doesn't appear to be working. (or i'm
> screwing something up...)
> 
> i i'm on box1 (which is windows), and i do a ping 192.168.2.33 (which is the
> eth0 nic) on box2, i'm assuming i have to do something to "translate" the
> 192.168.2.33, into 192.168.1.33 (which is the ath0) on box2. the only way
> box1 can get to box2 is via the ath0 (wireless) nic..
> 
> any thoughts/comments/pointers.

I think you should go over my first response and ensure you've done 
everything and read every relevant man page.

Within the bounds of your private network, regardless of how many 
subnets you use, you do not need to translate network addresses. You do 
need to get your routes right, and you do need to ensure IP forwarding 
is enabled at every gateway, and you do need to ensure your firewalls 
allow the traffic you want.

Tecnically, you _can_ use NAT on your private network, unless you want 
every host to be able to access at least one host on every subnet.

have this setup:
<internet> == <gateway>
    == 192.168.4.x == <router>
    == 172.17.0.x == <router>
    == 192.168.9.x

on my setup, every machine on every network can directly access every 
other. if I used NAT at any point, that would not be possible.

I also run VPNs on the gateway to other locations; those other locations 
on other private network addresses also have direct access (limited by 
firewall rules).

> 
> 
> bruce wrote:
>> Hi John!!
>>
>> I've forgotten something, as I thought this was working at one time, so
> it's
>> back to the basics....
> 
> You haven't said whether you're using network mangler. It will not work
> with network mangler.
> 
>> to begin, i have two boxes:
>>
>>   box1              -->>>     box2
>>
>>  box1
>>   eth0 - 192.168.1.2
>>
>>  box2
>>   ath0 - 192.168.1.5
>>   eth0 - 192.168.2.5
>>
>> from box1, i can ping box2/ath0 as they're on the same subnet. i can't
> ping
>> box2/eth0.
>>
>> from box2, i can ping box1. on box2, i can ping both nics.
>>
>> how the heck do i setup box2 so box1 can ping box2/eth0??
>>
>> is there a route cmd i can try on box2 that does a forward of traffic? is
> 
> man route
> 
>> this even possible? i'm pretty sure it should be possible. while i'm
>> focusing on just a single box to connect to box2/eth0, i want to have all
>> the boxes in my system eventually connect to box2/eth0, just like they do
>> with box2/ath0... i shouldn't have to have a route cmd on each box,
>> particulary as some boxes are windows, and don't have route!!
>>
>> so.. what's the simple solution for this issue?
>>
>> i can post my iptables/route output on box2...
>>
>> thanks
>>
>>
>> -----Original Message-----
>> From: fedora-list-bounces at redhat.com
>> [mailto:fedora-list-bounces at redhat.com]On Behalf Of John Summerfield
>> Sent: Saturday, November 24, 2007 6:46 PM
>> To: For users of Fedora
>> Subject: Re: ip masquerading
>>
>>
>> bruce wrote:
>>> hi...
>>>
>>> i have a situation where i have a system with two connections, one
>> wireless,
>>> one eth connetion. i can currently connect with the wireless ath0 to my
>>> network/internet/etc...
>>>
>>> however, when i activate the eth0 at the same time, i can't access the
>>> network via ath0. as far as i can tell, i need to implement ip masquerade
>> to
>>> have eth0 map, to ath0...
>>>
>>> my test ip addresses are:
>>>  ath0 - 192.168.1.33
>>>  eth0 - 192.168.2.33
>>>
>>> any thoughts/comments/pointers...
>> You don't need IP masquerading, unless this system's going to be a
>> gateway to the Internet for other computers.
>>
>> You don't need IP masquerading if some other device is already doing it.
>> The other device does need enough routes to access everything connecting
>> through it, but in the usual case (you only have one subnet) that's how
>> it's working. In your case, I assume you're using a "hardware" router
>> and it's IP address is 192.168.1.1 or 192.168.1.254 (these are defaults
>> for some brands). If it can be configured to route traffic to
>> 192.168.2.33 via 192.168.1.33, then you don't need IP masquerading, you
>> just need to configure the route.
>>
>> You do need both interfaces active at the same time, and network manager
>> cannot do that at present, I've just engaged in a lengthy discussion
>> about that either on this list, or on -test.
>>
>> I don't know whether network manager can be configured to do one network
>> and not the other.
>>
>> In addition to configuring both network interfaces to be active at the
>> same time, you also need to enable forwarding in /etc/sysctl.conf
>>
>> Here's script I run for myself, for a similar task. It doesn't show
>> everything, and it won't suit you without some work.
>> [root at localhost ~]# cat bin/startrelay
>> #!/bin/bash
>> ifdown eth0
>> ifconfig eth0 172.17.0.1
>> route add -net 192.168.9.0 gw 172.17.0.19  netmask 255.255.255.0 eth0
>> service dhcpd restart
>>
>> [root at localhost ~]#
>>
>> ath0 in this system provides access to the Internet via a Linux system
>> function as an Internet gateway. It's configured via
> system-network-config.
>> "ifdown eth0" takes down the configuration established by
>> system-config-network for eth0, I don't want this configuration to be
>> standard.
>>
>>
>> --
>>
>> Cheers
>> John
>>
>> -- spambait
>> 1aaaaaaa at coco.merseine.nu  Z1aaaaaaa at coco.merseine.nu
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>>
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>>
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> 
> 
> --
> 
> Cheers
> John
> 
> -- spambait
> 1aaaaaaa at coco.merseine.nu  Z1aaaaaaa at coco.merseine.nu
> -- Advice
> http://webfoot.com/advice/email.top.php
> http://www.catb.org/~esr/faqs/smart-questions.html
> http://support.microsoft.com/kb/555375
> 
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-- 

Cheers
John

-- spambait
1aaaaaaa at coco.merseine.nu  Z1aaaaaaa at coco.merseine.nu
-- Advice
http://webfoot.com/advice/email.top.php
http://www.catb.org/~esr/faqs/smart-questions.html
http://support.microsoft.com/kb/555375

You cannot reply off-list:-)