Noob ifconfig question :-/ ...

[Michael Powell]

William A. Mahaffey III wrote:

> On 10/24/14 11:49, Gary Aitken wrote:
>>> ... I have been tussling w/ getting my newly acquired WatchGuard FireBox
>> Edge firewall appliance setup. It requires a computer on the LAN on its
>> own IP block (192.168.111.0/8), w/ netmask 255.255.255.0. I was/am
>> trying to use ifconfig to set this box up on that block (temporarily
>> !!!) to get that thing setup & configured. When I (successfully) reset
>> my IP address to 192.168.111.27, I am able to access the device w/ my
>> browser. However, it asked for a user name & passwd, which I don't have
>> & which the manual which came w/ it doesn't specify :-/ .... Any clues
>> what those might be .... Slightly OT, I realize, however I will probably
>> later try to change it over to *BSD, as per an earlier post, in case
>> that helps .... TIA for any & all clues ....
>>
>> A quick web search shows
>>    admin/admin
> 
> 1st thing I tried, nogo :-/ ....
> 
>>
>>> Separately, when I reset the IP address of this box back to normal
>> (192.168.0.27), I could no longer access the web, or my DSL modem (on a
>> different subnet behind a router (to be replaced by the afore-mentioned
>> firewall)) w/o rebooting. When I did an 'ifconfig re0', I got almost the
>> same output as before my twiddling, except that the 'inet' & inet6'
>> lines were switched (inet before inet6 before twiddling, inet after
>> inet6 after twiddling) .... Could that be the cause of my inability to
>> access the modem & web ? TIA here also :-/ ....
>>
>> That's because you changed the third digit of the ip address, and it is
>> no longer in the same subnet
>> as the rest of your network, which you just changed over to
>> 192.168.111.27.  If I understand what you
>> said above correctly.  All of the boxes have to reside on the same
>> subnet, either 192.168.111.* or
>> 192.168.0.*, in your scenario above.
> 
> 
> Everything is on subnet 192.168.0.nnn/8, *except* the new firewall, so I
> set *just* my computer (this box, FBSD 9.3p2) to the 192.168.111.nnn/8
> subnet using ifconfig. I could indeed reach the firewall through my
> simple switch (Netgear from Best Buy). However, when I set this box
> *back* to my usual subnet, nothing past the router (which the firewall
> is intended to replace) worked w/o a reboot.
> 
> 
I'm not expert, but /8 CIDR is a network of 192.0.0.0 - not 255.255.255.0 
which is /24. I suspect what possibly may be at the core of the problem is 
your sub-netting arrangement. In order to be in the same 'network' segment 
subnet mask needs to be set correctly.

Back in what was called the 'Class C' days one of the private non-routable 
(rfc 1918) blocks of 192.168.0.0 is subnetted to /24. A /8 is incorrect but 
I probably misunderstand what's going on here. (/8 would be a correct subnet 
for a 10.0.0.0 rfc-1918 network)

I don't think I understand your trouble completely, it's just this kinda 
jumps out at me as something I don't understand and therefore call in to 
question.

-Mike