PING to test

Networking/Security Forums -> UNIX // GNU/Linux

Author: gigsvoo PostPosted: Wed Dec 11, 2002 9:20 am    Post subject: PING to test
Hi there,

This question seems to be over wimped, but I still have to ask.

In Windows, we can test the MTU package size by using:

C:\> ping -F -I nnnn nnn.nnn.nnn

(where n is numbers Wink )

Rolling Eyes But, in UNIX/Linux, how do I do the same thing?

The reason being is I thought of can do the same thing similar to this article in Linux?,39006400,39089320,00.htm

What do you think?

Author: ShaolinTigerLocation: Kuala Lumpur, Malaysia PostPosted: Fri Dec 13, 2002 12:00 pm    Post subject:
You can check the performance with:

eth0 Link encap:Ethernet HWaddr 00:08:C7:33:F3:A8
inet addr: Bcast: Mask:
RX packets:3521270 errors:0 dropped:0 overruns:0 frame:0
TX packets:2930688 errors:3 dropped:0 overruns:0 carrier:3
collisions:0 txqueuelen:100
RX bytes:3866756450 (3.6 GiB) TX bytes:2179422397 (2.0 GiB)
Interrupt:5 Base address:0x2800

MTU is shown in ifconfig

Some info on optimising here:

You can usually set it with ifconfig ethX mtu NNN

man ifconfig for more info.

Hope this is what you need Smile

Author: gigsvoo PostPosted: Mon Dec 16, 2002 3:11 am    Post subject:
I have been told that the best value for LAN is 1492, do you agree? Why?

Author: WeaverLocation: WI, USA PostPosted: Sat Jan 04, 2003 6:53 am    Post subject:
Just out of curiosity, where did you hear that from? Did they say why?


Author: gigsvoo PostPosted: Sun Jan 05, 2003 5:07 am    Post subject:
That is on ExtremeTech forum. Someone told me that this is the general working MTU size. But I do make a test and found that my environment work best in 1470.

Author: max_blakkLocation: South Wales UK PostPosted: Sun Jan 05, 2003 3:24 pm    Post subject:
Try getting Hping for Linux very nice tool...


You can have fun with friends with this, make um think they are being probed by Yahoo... Laughing (but be sure to test on your own machines first with a packet sniffer. Ethereal rocks at this... Smile )

With the mtu I use 1460 1500 minus the standard packet header 40 bytes.

Also I have additional commented lines in my options file for a lower mtu for gaming. I get better latency and faster game play with around 552 mileage varies though.


Author: squidlyLocation: Umm.. I dont know.. somewhere PostPosted: Sun Jan 05, 2003 8:18 pm    Post subject:
In general the twisted pair only makes the packed 1500 bites for each packet. Most OSes dont bother to play with the ethernet headder and let that be set and handeled by the card (if I rembemer correctly) and the 1460 MTU is the packet size minus the 40 bit headder.

That is generaly the size for ethernet. I'm still trying to figure out why they decided on such a small size for the packet though. Propibaly because of the expence of memory way back when (before memory was measured in KB Smile).

If you want to take down a network try playing with a small packet size like about 500 bites and then start pinging places. hping is a great tool.. Very usefull for playing with packets. Also check out fragrouter (I dont have a url for that but I know you can find it on google).

Check out RFC826 for more information on the ethernet protocols.

Author: gigsvoo PostPosted: Mon Jan 06, 2003 3:42 am    Post subject:
OK, great xplanation guys thanks alot! But do your think that the MTU size works for me? I am running in a 10MBps LAN and connected thru a floor switch (actually is a hub coz some floors uses 100MBps but ours still 10Mbps), and connected to the backbone of ATM.

Crying or Very sad

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