Default OM settings, no lan messed up

[Joel Newkirk]

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')

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

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.  

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.

j