D&C Lug - Home Page
Devon & Cornwall Linux Users' Group

[ Date Index ][ Thread Index ]
[ <= Previous by date / thread ] [ Next by date / thread => ]

Re: [LUG] Do other LUG Members find X a pain to configure ?



On Wednesday 09 April 2003 9:07 pm, Julian Hall wrote:
>

http://www.google.co.uk/linux  is your friend.

> 1. What is "promiscuous mode"?
;-> promiscuous merely allows that interface to receive all packets on the
> ;-> network.
http://isp-lists.isp-planet.com/isp-linux/0102/msg00078.html
This message talks about an attack on the box but just having eth0 in 
promiscuous mode doesn't mean an attack is easier or more likely if the 
network itself is behind a firewall.


> 2. I noticed the MTU is 1500.. is this OK for a 1Mb cablemodem or should
> I look at altering it? (always remembering the tech's Golden Rule..
> "Don't fix what's NOT broken!"  If I should alter it, err.. how please?
--------------------------------
http://mail.nl.linux.org/linuxperf/2001-08/msg00001.html
Well I know why the MTU should be set to 1500 bytes. That's a bit less
than the MTU on ethernet. So if your ISP uses Ethernet (which they
probably do), you can't send larger packets than about 1500 byte. If you
had a higher MTU value, your computer would send longer packets and they
would have to be split up before transmission. If the value is to small
you would send to many packets, each one with it's own header. That
would slow down the transmission, too. So about 1500 bytes is rather
well. You might still go a bit higher to maybe 1600 bytes before they
get splitted up, but that's not sure. For example with PPPoE (ADSL) the
maximum MTU you should set is 1502.
------------------------------
1500 | 1502 - I'd say there wasn't really much to gain.

> 3. When I boot up the nvnet (ethernet) module is "tainted".  Now I've
> found out that this means NVidia didn't bother "signing" it properly,

Signing? That's more like XP. What is a bit more likely is that NVidia haven't 
released the source code for the driver so that you have to install a binary 
that doesn't fit 100% with the surrounding Free Software. You've got a bit of 
patented/protected/closed source binary code that has not been released under 
an open licence like GPL. It doesn't mean that the two pieces won't work 
together, it just means that you are still tied to proprietary software and 
restrictive licences whereas other cards have open source drivers. It's about 
the 'purity' of what would otherwise be a fully open source machine.
http://www.codehelp.co.uk/code/gpl.html

Here's another reason for 'tainted' messages:
----------------------------------
http://lists.maconlinux.org/pipermail/mol-general/2002-July/000472.html
> So what does this "tainted kernel" thing mean? When I ran startmol --test
> it displayed "test successful".

you get this message if you do things like

1) load a module not specifically compiled for YOUR version of the kernel
2) load a non-GPL'd module code

generally. there are another couple of reasons, but they arent as common.

its not 'too bad' a thing.
-------------------------------------

> although as I said it works OK.  Is this something I should be bugging
> them about?

Yes, if you can. Most network cards are already served by open source drivers 
- it's worth considering in your next hardware purchase.

> alias eth0 nvnet

I used a real cheap card from PCWorld badged by LinkSys and these cheap cards 
pay off - the feature set is basic but adequate and the driver support is 
comprehensive.


-- 

Neil Williams
=============
http://www.codehelp.co.uk
http://www.dclug.org.uk

http://www.wewantbroadband.co.uk/

Attachment: pgp00011.pgp
Description: signature


Lynx friendly