Ping the broadcast address

**Gunner 1** · 31-12-2009

Hello,
After reading some articles , I noted that one of them could be done with a ping on the broadcast address (we will not speak on the MAC address spoofing ). Since this technique is widespread, network administrators are sure to prohibit this kind of ping.
I say out of curiosity, why not try it on my network taf. I calculate the broadcast address, I make my table and watch what happens with wire shark.

MSRP:
My IP Address: 141.11.147.184
Subnet Mask: 255.255.240.00
Broadcast Address: 141.11.159.255
My ARP cache is composed of ten address.

What I see in console back:

Code:

H: \> ping 141.11.182.255
Pinging 141.11.182.255 with 32 bytes of data:
Request timed out.
Request timed out.

Why this time out? Is this normal in the case of a broadcast ping?
I note that it is the broadcast address that replied 8 times for each attempt, then it is timeout. You'd know why I did not see the IP addresses of machines that meet me? Protection made by the administrator?
After that, I check the status of my ARP cache and visibly, I have a hundred addresses. I should have much more, why is not this the case? Could this be due to a phenomenon of collision and therefore packet loss? If so, is there an option to avoid this (without ping one by one the machines)?

**Snake08** · 31-12-2009

Hello
This is certainly the collision that you do not see anyone (or you have VLAN?)
why do you avoid this? The ping a broadcast address is anyway to avoid. I can not understand why are you trying this, which is not at all necessary. Are you sure what you want, what will you do with the data which you will get after that. In my opinion this is unnecessary.

**Gunner 1** · 31-12-2009

Hi,

This is certainly the collision that you do not see anyone (or you have VLAN?)

Pure VLANs, I do not know, how can I deduct?

why do you avoid this?

In fact, just out of curiosity.

The ping a broadcast address is anyway to avoid

I doubt this.
Can I get an explanation on the output of wireshark and ping?

**Snake08** · 31-12-2009

Hello
For VLAN, you can always ask the person who manages the network but if there are many posts, there are things there VLANs, it can just limit the broadcast. On the table, certainly that the machines are configured to not respond to ping (this often happens with a firewall), I do not know for wireshark, sorry.

**Gunner 1** · 31-12-2009

Hi
Ok thank you for your answers. I have read that there are VLANs within the company. By cons I do not know how it works and what is the point. If you want to give a brief explanation is as you wish. Anyway, when I had a little time I throw a look on my friend. If others have an idea of what is visualized with wireshark can post back and help me.

**Snake08** · 31-12-2009

Hello
Briefly, a VLAN is a group of machine-level logic. This allows you to give more flexibility eg a bang for the commercial, a vlan for the technique, a bang for the marketing. So then you can define different security policies depending on your vlan (although all these machines are on the same physical network) Moreover, it reduced the area of broadcasting. When you send a broadcast, only with the machines you can bang your answer. Otherwise as you say, google will give you more details.