Nope, no response. I never did figure it out. I just rearranged my network so the machines I want to monitor (i.e. the Windows ones!) are attached to the device which allows tcpdump to watch what they're doing. I still find it really odd.... On Wednesday 09 April 2003 14:37, Steven Augart wrote:

Derek,

Did you ever get an answer to your Ethernet Hubs question?

It certainly sounds to me as if you got more than you paid for.

--Steve Augart

Derek Fountain wrote at 16/02/2003 02:11 (GMT-0800):

...

I have, amongst my collection of bits, two ethernet hubs. One is by Netgear and one by Linksys. Both work. I have 3 machines, 1, 2 and 3.

I plug them all into the Netgear hub.

I log onto box 2 (at the console) and ping 3. Away to goes, every second. I open a tcpdump on 1 and watch the packets going by.

I now plug all the cables into the Linksys hub and repeat the experiment. Nothing!

When the machines are connected via the Linksys hub, tcpdump can't see the packets going from one machine to another, unless, it turns out, the machine running tcpdump is the one being pinged.

The Linksys device is a hub, not a switch! I know, I paid for it!

Anyone know why this is the case? Does Linksys stuff have some anti-snooping, don't-pass-through-to-promiscous cards sort of thing in it?

-- "...our desktop is falling behind stability-wise and feature wise to KDE ...when I went to Mexico in December to the facility where we launched gnome, they had all switched to KDE3." - Miguel de Icaza, March 2003

On Wed, 09 Apr 2003 09:45:03 -0700 Magnus Hagebris wrote:

What's the linksys model name?

I usually double check my IP settings, especially the netmask when strange things happens.... It shouldn't make a difference on a hub; but you never know... I used to have a Linksys hub as well as a switch. One thing you've got to be careful about is that some Linksys hubs have an uplink/downlink switch so you can daisy chain multiple hubs.

Also, your ethernet cards should be set to half duplex for hubs, but full duplex for switches. And, with a hub, all the systems attached to that hub should be running the same speed. Most will autosense correctly. The bottom line is that as long as your routing tables are set up correctly in your systems, each system should be able to ping eachother. BTW: With a switch, you may have a combination of 10Mbps and 100Mbps, but with a hub, as I mentioned above a single 10Mbps system on the hub will cause just about every other system to run at 10Mbps (there are some exceptions). -- Jerry Feldman Boston Linux and Unix user group http://www.blu.org PGP key id:C5061EA9 PGP Key fingerprint:053C 73EC 3AC1 5C44 3E14 9245 FB00 3ED5 C506 1EA9

I bought four Linksys HUBS for my work a while back, for the express purpose of being able to sniff some traffic. Couldn't do it. Opened a unit, and googled for the chip part number. It was an ethernet switch part number. The chip manufacturer's web site claimed a new breakthrough technology that lowered the price point to the point that their chips could be used instead of simple repeater chips.

Interesting. In my case it's a Linksys which is clearly a hub, not a switch, but it's interesting that the components can be, and are, interchanged quite readily. Maybe my Netgear hub is actually a switch after all. That would certainly make sense with regard to what I'm seeing. -- "...our desktop is falling behind stability-wise and feature wise to KDE ...when I went to Mexico in December to the facility where we launched gnome, they had all switched to KDE3." - Miguel de Icaza, March 2003

...

I bought four Linksys HUBS for my work a while back, for the express purpose of being able to sniff some traffic. Couldn't do it. Opened a unit, and googled for the chip part number. It was an ethernet switch

Hi Doug, Switch : http://computer.howstuffworks.com/lan-switch.htm Router : http://computer.howstuffworks.com/router.htm Other useful info here : http://computer.howstuffworks.com/home-network.htm Hope this helps. - Mark Dodd -----Original Message----- From: Doug McGarrett [mailto:dougmack@i-2000.com] Sent: Friday, April 11, 2003 9:49 AM To: Derek Fountain; SuSE English Subject: Re: [SLE] Ethernet hubs question For those of use who are not IT savvy, what's the difference between a hub and a switch and a router? I have a Linksys "router" which, I believe, I could use to connect 2 or up to 4 computers in a network. I use it for its firewall capability. Could you, or someone, please explain what these words--hub, switch, router--actually mean? Thanx. --doug At 19:43 04/10/2003 +0800, Derek Fountain wrote: part

...

number. The chip manufacturer's web site claimed a new breakthrough technology that lowered the price point to the point that their chips could be used instead of simple repeater chips.

Interesting. In my case it's a Linksys which is clearly a hub, not a switch, but it's interesting that the components can be, and are, interchanged quite readily. Maybe my Netgear hub is actually a switch after all. That would certainly make sense with regard to what I'm seeing.

-- "...our desktop is falling behind stability-wise and feature wise to KDE ...when I went to Mexico in December to the facility where we launched gnome, they had all switched to KDE3." - Miguel de Icaza, March 2003

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For those of use who are not IT savvy, what's the difference between a hub and a switch and a router? I have a Linksys "router" which, I believe, I could use to connect 2 or up to 4 computers in a network. I use it for its firewall capability. Could you, or someone, please explain what these words--hub, switch, router--actually mean?

A hub is the simplest of the three. A hub merely simulates a single wire that all machines are connected to and share bandwidth from - either 10 or 100 Mbit/s, and only in half duplex mode. That is a machine may only transmit or receive at any one time. Full duplex mode - the ability to simultaneously transmit or receive - requires a switch. Only one machine can transmit on the "wire" at a time. Other machines must wait. If a machine transmits while another machine is transmitting the packets of data will collide - a collision in technical terminology. When a collision occurs the packets involved must be resent. This obviously slows down your connection. A (layer 2) switch is a "smarter" device and offers more bandwidth through "virtual" connections. When two machines wish to communicate the switch configures a dedicated connection between the two. Many of these connections can be created on the same switch between many different machines. The number of connections that can be maintained is limited by the speed and bandwidth available on the "backplane" of the switch. The backplane consists of the internal "mesh" that connects all ports on the switch and the processor or processors in the switch (some switches have seperate processors per port, some use a single processor). Each connection to the switch can be negotiated at either 10, 100, or 1000 Mbit/s and at half or full duplex modes (with some exceptions. Some older switches only worked at 10 Mbit/s or only in half duplex mode). A router is used to connect two different networks or network topologies. For example connecting your internal LAN to your ISP's lan requires a router. Connecting your machines to your LAN requires a hub or switch. As you know based on the device you own these devices can be configured in the same box. Some advanced switches - called "layer 3" or higher switches - can actually perform routing. In many enterprises many routers have been replaced by these types of switches. That's obviously the mile high view, and I've over simplified in a lot of places, but hopefully that was of some help. -- John LeMay KC2KTH Senior Enterprise Consultant NJMC | http://www.njmc.com | Phone 732-557-4848 Specializing in Microsoft and Unix based solutions