Ubuntu
netcfg package

Can't set MTU during installation

Bug #32355 reported by feralert
8
Affects Status Importance Assigned to Milestone
netcfg (Ubuntu)
Confirmed
Wishlist
Unassigned

Bug Description

Using alpha4 i386 dapper release at the moment (but had this problem with earlier ubuntu releases too).

The installation founds my nic fine and prompts for ip address, mask, gateway, dns, etc... but doesnt prompt for MTU so it tries to download files and since it cant access them it just stays there forever and the installation process does not continue.

I have a pppoe connection and my router dials in for me (so i dont need to use pppoeconf or anything else) but it is a must to set MTU to 1492 (this is so in window$ too).

I manage to continue the installation by switching to ALT+F2 and manually setting mtu to 1492 with 'ifconfig eth0 mtu 1492', but i think thats too much trouble for a newbie. Besides, when the installation finishes and the system reboots the MTU setting of 1492 is gone so you log in and you have no internet connection working so you have to manually edit /etc/network/interfaces and add a new line with 'mtu 1492' in the section of the interface you use to connect to the net.

Could MTU be asked during install??

Regards,
Fernando.

P.S.:Sorry if this is not the place to say this, its my first time using this reporting thing, so i apologize if this is not done this way.

Revision history for this message
Dennis Kaarsemaker (dennis) wrote :

Such questions generally are not added to the installer, but changing the package to the correct one will at least make sure the question reaches the right person :)

Revision history for this message
Dennis Kaarsemaker (dennis) wrote : Re: [Bug 32355] Can't set MTU during installation

 subscribe <email address hidden>

Revision history for this message
Matt Zimmerman (mdz) wrote :

If a nonstandard MTU is required, it should be provided by the DHCP server so that everything works automatically

Revision history for this message
Fernando Domínguez Flórez (feralert) wrote : Re: [Bug 32355] Re: Can't set MTU during installation

But what if you use static addressing instead of getting it from a
DHCP server? (which, BTW, is my case).

On 4/4/06, Matt Zimmerman <email address hidden> wrote:
> If a nonstandard MTU is required, it should be provided by the DHCP server so that everything works automatically
>
> ** Changed in: netcfg (Ubuntu)
> Severity: Normal => Wishlist
> --
> Can't set MTU during installation
> https://launchpad.net/malone/bugs/32355
>

Revision history for this message
Matt Zimmerman (mdz) wrote : Re: [Bug 32355] Re: [Bug 32355] Re: Can't set MTU during installation

On Wed, Apr 05, 2006 at 08:45:55AM -0000, Fernando Domínguez Flórez wrote:
> But what if you use static addressing instead of getting it from a
> DHCP server? (which, BTW, is my case).

Then this is an even smaller corner case than I originally thought. ;-)

Most commonly, a non-default MTU is not appropriate at all.
When it is, it should generally be provided by the DHCP server.
If it isn't, then packets should simply be fragmented automatically.
If the router doesn't do that properly...only then is there a problem.

--
 - mdz

Revision history for this message
Pavel Šimerda (pavlix) wrote :

But.... it seems ubuntu applications send packets with the Don't Fragment bit set. So this really is an issue.

Anyway I wouldn't add any question to the installer. Changing MTU is for expert users (you have to yous registers even on windows).

I suggest editing '/etc/network/interfaces' (and using 'man interfaces' to get help). It's simple and it
s the right way to do network configuration. During install you can use either 'ifconfig' or 'ip'.

If this is right, can the bug be closed?

Revision history for this message
Rodolfo Bonnin (bonninrodolfo) wrote :

Well, I'm not sure if this can be an example, but the utility pppoeconf asks this sort of question, explaing the possible corner case. Maybe an "Advanced" tab or an "Advanced..." button?
Regards.

Thomas Hotz (thotz-deactivatedaccount)
Changed in netcfg (Ubuntu):
status: New → Confirmed
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