Default OM settings, no lan messed up

[Sarton O'Brien]

On Tuesday 14 October 2008 13:38:45 Joel Newkirk wrote:
> On Tue, 14 Oct 2008 12:57:07 +1100, "Sarton O'Brien"
>
> <roguemoko at roguewrt.org> wrote:
> > On Tuesday 14 October 2008 06:14:35 Joel Newkirk wrote:
> >> PS: ipcalc is a handy tool...  
> >>
> >> $ ipcalc -b 192.168.1.20/29
> >> Address:   192.168.1.20        
> >> Netmask:   255.255.255.248 = 29
> >> Wildcard:  0.0.0.7              
> >> =>
> >> Network:   192.168.1.16/29      
> >> HostMin:   192.168.1.17        
> >> HostMax:   192.168.1.22        
> >> Broadcast: 192.168.1.23        
> >> Hosts/Net: 6                     Class C, Private Internet
> >
> > But you'll lose those awfully useful on-demand binary skillz :)
> >
> > Seriously though, nice tool. Would have been really handy when I was
> > bothering
> > with cisco, if only to give to the people looking over my shoulder ;). I
> > swear
> > they sit around trying to figure out how to confuse people as much as
> > possible.
> >
> > Sarton
>
> sort of like riding a bicycle...  My first computer I programmed via a hex
> keypad, 1802 machine code (no assembler, no mnemonics, just hex opcodes),
> so at the start of things I became (painfully) familiar with
> hex<->dec<->bin relationships, masks, and binary arithmetic.  (I still see
> things like 'a*8' while my brain thinks 'a<<3')

I agree, though I haven't ridden that bicycle for a very long time. Although 
I've done some programming using hex on the z80s, I was always very fluent at 
deriving binary logic and determining boolean expressions by briefly looking 
at a diagram. So shuffling binary around in my head was never an issue, but 
the base 10 conversion was. Hex <-> binary was always easier but most likely 
due to the typically quad/octal nature of computing.

> For the people over your shoulder you should omit the '-b' flag, which
> tells it to skip the bitwise output... ;)
>
> $ ipcalc 192.168.1.20/29
> Address:   192.168.1.20         11000000.10101000.00000001.00010 100
> Netmask:   255.255.255.248 = 29 11111111.11111111.11111111.11111 000
> Wildcard:  0.0.0.7              00000000.00000000.00000000.00000 111
> =>
> Network:   192.168.1.16/29      11000000.10101000.00000001.00010 000
> HostMin:   192.168.1.17         11000000.10101000.00000001.00010 001
> HostMax:   192.168.1.22         11000000.10101000.00000001.00010 110
> Broadcast: 192.168.1.23         11000000.10101000.00000001.00010 111
> Hosts/Net: 6                     Class C, Private Internet

Yep, this program would have saved me a lot of time ;)

> Seems most people who don't understand binary all the way down to their
> souls can't even see the dotted quads, their eyes and brains get stuck on
> the 'big' block of binary.

You mean octal yeah?

> For those interested in achieving understanding of netmasks it can be
> helpful to generate a few of these for familiar networks and look at the
> binary portion... The meaning of a /29 netmask for example is pretty clear
> above.

I second that. Anyone who doesn't completely understand what they are doing 
when they alter routes, IPs and netmasks should make sure to investigate 
further. Worst case you might light up an area of your brain that hasn't seen 
activity in a while :)

Sarton