Xen: Console Not working Ubuntu 7 // Crucial Paradigm

Some of the default HyperVM templates have an issue with nash-hotplug taking a large amount of resources (usually 99%). If you are having this issue, a quick an easy way to fix this is add the following to /etc/rc.local on the guest VDS:

pkill -9 nash

This is a temporary fix, until a more permanent one is provided by Lxlabs/HyperVM. This problem is supposedly already fixed in CentOS 4, however seems to still appear in Debian 3. For debian, do the following:

Open up /etc/init.d/local and add:

#!/bin/bash
pkill -9 nash

Then run the following:

chmod 755 /etc/init.d/local
update-rc.d local start 98 2 3 4 5 .
mkdir /etc/rc.d/
ln -s /etc/init.d/local /etc/rc.d/rc.local

Tags: debian, hypervm, vds, xen

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Filed under: Uncategorized by — aaron @ 5:10 pm

February 25, 2008

Configuring Network Interfaces on CentOS, Redhat, Fedora Core, and Debian

CentOS/Red Hat/Fedora Core:

The network configuration files are in the folder:
‘/etc/sysconfig/network-scripts’

The files for the interfaces will be ifcfg-eth0, ifcfg-eth1, ifcfg-eth0:0 (if there are sub-interfaces)

Static IP address configuration:
——————–
[root@sXXX network-scripts]# cat ifcfg-eth0
# Intel Corporation 82573L Gigabit Ethernet Controller
DEVICE=eth0
BOOTPROTO=static
HWADDR=YY:YY:YY:YY:YY
BROADCAST=XXX.XXX.XXX.XXX - specify the broadcast address here
IPADDR=xx.xx.xx.xx - specify the IP address here
NETMASK=255.255.255.0 - specify the netmask here
ONBOOT=yes
TYPE=Ethernet
———————-

Please specify ‘ONBOOT=yes’ which will activate the interface upon system boot

Dynamic IP address configuration: Change BOOTPROTO value to dhcp
——————–
[root@sXXX network-scripts]# cat ifcfg-eth0
# Intel Corporation 82573L Gigabit Ethernet Controller
DEVICE=eth0
BOOTPROTO=dhcp
ONBOOT=yes
TYPE=Ethernet
———————-

To bind a range of IP address, create a file called ifcfg-eth0-range0 (for example eth0:0, eth0:1, etc)

The entries should be:

——————————-
IPADDR_START=192.168.0.10
IPADDR_END=192.168.0.20
CLONENUM_START=0
NETMASK=xxx.xxx.xxx.xxx
——————————–

IPADDR_START: This is the first IP from the address range you want to bind to your ethernet device.
IPADDR_END: This is the last IP from that address range.
CLONENUM_START: This is the number that will be assigned to the first IP alias interface. For instance, if your Internet interface is eth0 and CLONENUM_START is 0, then this config file will create 10 interfaces starting with eth0:0 (eth0:0, eth0:1, eth0:2 etc) and ending with eth0:10.

The gateway for the network can be specified in the file ‘/etc/sysconfig/network’
——————————-
NETWORKING=yes
HOSTNAME=hostname
GATEWAY=”XXX.XXX.XXX.YYY”
———————————
Once you assign the IP addresses and configure the gateway please restart the service network ‘/etc/init.d/network restart’

You may also use ‘/usr/sbin/system-config-network-tui’ to configure the network interfaces

Debian:
In Debian the interface configuration file is ‘/etc/network/interfaces’

The entires are:
———————————
auto lo
iface lo inet loopback

auto eth0
iface eth0 inet static
address xxx.xxx.xxx.xxx
netmask yyy.yyy.yyy.yyy
broadcast xxx.xxx.xxx.xxy
network xxx.xxx.xxx.xxz
gateway xxx.xxx.xxx.xxw
———————————

After you configure the network interfaces restart the network service using ‘/etc/init.d/networking restart’

Tags: centos, debian, fedora core, networking, system administration

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Filed under: Uncategorized by — aaron @ 12:01 am

February 17, 2008

Resetting lost root password in Debian server

In Debian getting into just the single user mode may not allow you to reset the root password. It might prompt you with the following question

‘Give root password for maintenance (or Control-D to continue)’ .

Don’t worry, reboot the server.

(1) At grub boot screen, select the kernel and press ‘e’ to edit the entry.

(2) Another list will show up. Scroll down and pick from the list something that looks like this (or something similar):

kernel /vmlinuz-x.x.x-x.x ro root=/dev/abc/

(3) Type ‘e’ again to edit this line. Make sure that you press the space bar and add the following:

init=/bin/bash

(4) Then press enter. The line should look something like this then:

kernel /vmlinuz-x.x.x-x.x ro root=/dev/abc/ init=/bin/bash

(5) Press ‘b’ to boot. This will take you into a bash terminal. From there you’ll have to mount your hard drive and allow for read/write permissions.

(6) mount -o remount,rw /

You need to do this because / is currently mounted read-only and many disk partitions might have not been mounted yet.

If you have to see the mount details. Type the command

mount

It should come up with something like, for /:

/dev/abc (rw)

It looks like it’s already set for read/write permissions, but it’s not (just try and reset the password with the passwd command and see what happens). To mount it again type the following command:

mount -o remount,rw /dev/abc /

(7) Now you should be able to change the root password by issuing the following command:

passwd

(8) After the password has been reset, type ‘reboot’ and reboot the server.

The job is done

Note:

For LILO:

(1) As the server reboots, you might have to hold in the “shift” key to see the lilo: prompt (depending on the setup)

(2) At the lilo boot screen, as soon as ‘boot:’ appears enter:

boot: Linux init=/bin/bash

This causes the system to boot the kernel and run /bin/bash instead of its standard init.

Follow the same procedure of remounting slash as with GRUB.

Tags: debian, linux, system administration

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Filed under: Uncategorized by — aaron @ 2:39 pm