[SOLVED] How to change MTU value (and make it stick)?

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robenroute
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Posts: 80
Joined: Wed Feb 10, 2010 3:34 pm

[SOLVED] How to change MTU value (and make it stick)?

Post by robenroute » Thu Mar 19, 2015 12:04 pm

Hi there,

I'm struggling with setting up VPN connections reliably and was advised (by the VPN provider) to change my system's (17.1) MTU value to something between 900 and 1100. Although this strikes me as being on the low side, the default value apparently is 1500

Code: Select all

ifconfig | grep MTU
My system is connected to my DSL-modem/router via an ethernet cable if that is of any help.

Although I'm not a networking expert, I do understand the basics ans so I've perused several postings regarding this topic, but the offered "solutions" have not been able to provide anything useful:

1. http://serverfault.com/questions/608931 ... amazon-vpc
I've changed the dhclient.conf file to include:

Code: Select all

interface "eth0" {
        default interface-mtu 1492;
        supersede interface-mtu 1492;
}

interface "lo" {
        default interface-mtu 1492;
        supersede interface-mtu 1492;
}
In the comments/feedback, someone mentioned that a certain ethtool command should be entered to make things work. Because my system doesn't recognise eth0 (it does know lo), I tried

Code: Select all

sudo ethtool -K lo sg off
but I got a notice that scatter-gather (what on Earth is that?) could not be changed.

2. http://ubuntuforums.org/showthread.php?t=1284176
Tried the "interface-mtu" settings before as well as after the "request" entry: no success

3. http://www.ubuntugeek.com/how-to-change ... linux.html
Tried the interfaces file: added MTU 1100, but no success


Is anyone able to offer a solution or a poiting in the right direction? Help would be much appreciated. Many thanks in advance!
Last edited by robenroute on Fri Mar 20, 2015 9:39 am, edited 2 times in total.

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mank_in
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Joined: Wed Nov 16, 2011 2:29 pm
Location: Bali

Re: How to change MTU value (and make it stick)?

Post by mank_in » Thu Mar 19, 2015 12:45 pm

What is yours vpn protocol , I am only use openVPN,
In open VPN, you can change MTU in VPN tab>advanced>general: use custom tunnel MTU
Image
Sorry for my bad English , I am Indonesian.

robenroute
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Posts: 80
Joined: Wed Feb 10, 2010 3:34 pm

Re: How to change MTU value (and make it stick)?

Post by robenroute » Thu Mar 19, 2015 4:13 pm

Thanks, mank_in! I completely missed that setting. How simple certain problems can be solved...

(Don't worry about your English; as long as people understand what you mean, all is fine! Furthermore, your English is much better than my Bahasa Indonesia :lol: )

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