Re: What would you like to see in next video?

[Hans Schou]

2011/10/20 Ole Tange <ole@tange.dk>:
> On Thu, Oct 20, 2011 at 1:01 PM, Hans Schou <chlor@schou.dk> wrote:
>> 2011/10/20 Ole Tange <tange@gnu.org>:
>>> On Wed, Oct 19, 2011 at 11:43 PM, Hans Schou <chlor@schou.dk> wrote:
>>>> On Sat, 15 Oct 2011, Ole Tange wrote:
>>>>
>>>>> It is probably time to get a new video out.
>>>>>
>>>>> What would you like to see demoed in that?
> :
>> Scan your private net for which IP-numbers is in use. Save data in a
>> file for later handling:
>>
>> time parallel --tag -j+128 ping -W2 -c1 192.168.112.{} \| grep from
>> ::: $(seq 254) | tee foo
>
> Good examples, though I would probably do:
>
>  seq 254 | parallel --tag -j0 ping -W2 -c1 192.168.4.{} |grep
> from|cut -f1|sort -nu
>
> Or use nmap, which has a much shorter syntax:
>
>  nmap -T insane -sP 10.10.13.0/24

Yes, but slow:

$ time nmap -T insane -sP 192.168.112.0/24
.... cut ....
real    0m17.153s
user    0m0.020s
sys     0m0.004s

With parallel and -j0 I am down to:
real    0m3.207s
user    0m0.840s
sys     0m1.480s

System usage is higher but Im alone on this box.

>> I use -j+128 here to start more ping's at the same time.
>
> You need to learn -j0.

Nice. That cut off 1.5sec (I will save them for later in my life).

/hans