Ubuntu Overssh Reinstallation

If your ISP/Datacenter dosn't provide standard or trusted iso for your server. Get ugly server from it with installed version of Ubuntu server.

I have same situation installed ubuntu has bad partition table or huge list of stupid package installed. Datacenter network is my primary concern or it's really cheap price but administrators dosn't care. What should i do? That's my way to solve this issue easily.

Ask them to install ubuntu server what ever is it. re install it over ssh, repartition and get clean installation of ubuntu server.

Create your own netiso and reinstall it over ssh. You can partion yor server as you desire. And set more configuration using ubuntu preseed just over ssh; no kvm/ipmi/vnc required.

It's simple, create modified iso based on your network and preseed url file and continue installation over ssh.

I use mini.iso because it's small and get most packages from ubuntu repository so you server after installation is fully updated.

⚠️ Requirement

1. Installed ubuntu version on server via ssh access
2. Root access require (or sudo user).
3. Clone this repo to your server
4. Copy config.sample to config file and edit field by field exactly:

   # country
   COUNTRY='IR'
   
   # network: check network before create iso file
   INTERFACE_DEV='eth0'
   INTERFACE_IP='10.1.1.100'
   INTERFACE_NETMASK='255.255.255.0'
   INTERFACE_GATEWAY='10.1.1.1'
   INTERFACE_NAMESERVERS='4.2.2.4'
   
   # preseed file: upload created preseed.cfg to your own host before reboot system
   PRESEED_URL="http://yourserver.tld/preseed.cfg"
   
   # ssh installer password
   PASSWORD="tHISiSpASSWORD"
   
   # hostname and domain
   HOSTNAME="${INTERFACE_IP//\./\-}"
   DOMAIN="example.tld"
   
   # lowercase of country code dont change it
   COUNTRY_LOWER="${COUNTRY,,}"
   

5. Upload your preseed.cfg file to your own host.

Find Predictable Network Interface Names

If your current installation of ubuntu not using Predictable Network Interface Names you can find out the name by using this command for example for eth0:

udevadm test /sys/class/net/eth0 2>/dev/null | grep ID_NET_NAME_
ID_NET_NAME_MAC=enxd4bed95f24db
ID_NET_NAME_PATH=enp7s0

You can use enp7s0 as predictable network interface name.

Clone repository

cd /tmp
git clone https://github.com/mhf-ir/ubuntu-overssh-reinstallation.git
cd ubuntu-overssh-reinstallation

Config

See config.sample and change it. ⚠️ Carefull about your network settings. It's can hold your server until get new kvm/ipmi/vnc to restore the ssh again.

cp config.sample config
vim config

Download network mini iso from ubuntu website

wget http://archive.ubuntu.com/ubuntu/dists/xenial/main/installer-amd64/current/images/netboot/mini.iso

Build iso

Remember you must do as root user

./create-iso.sh
...
Your network iso is ready '/tmp/ubuntu-overssh-reinstallation/ubuntu-overssh-reinstall.iso'

Update grub imageboot

Remember you must do as root user also

./grub.sh
...
Your password is tHISiSpASSWORD

Upload your preseed file

Upload your preseed.cfg file to configured location PRESEED_URL.

You can test it. We must get 200 response as we expected

curl -o /dev/null --silent --head --write-out '%{http_code}\n' http://yourserver.tld/preseed.cfg
200

⚠️ If your webserver not reachable you must reboot your server to get preseed file. so test it before reboot your server.

Reboot

reboot

Get ssh

Wait it until boot to iso complete and install require packages then

ssh installer@10.1.1.100

Continue installation of ubuntu

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✔️ This script test on Ubuntu Server 16.04 and 18.04.