Installation Over the Network

For installations on S/390, this is the default method after setting up the network.

You will be asked for a new password to be used for connecting to the installation system and for its confirmation. That’s all. Now you should see a screen which instructs you to login remotely as the 10. That is: press theAltkey on the left-hand side of thespace barand theF2function key at the same time.

Chapter 6. Using the Ubuntu Installer userinstallerwith the password you just provided. Another important detail to notice on this screen is the fingerprint of this system. You need to transfer the fingerprint securely to the person who will continue the installation remotely.

Should you decide to continue with the installation locally, you can always pressEnter, which will bring you back to the main menu, where you can select another component.

Now let’s switch to the other side of the wire. As a prerequisite, you need to configure your terminal for UTF-8 encoding, because that is what the installation system uses. If you do not, remote instal-lation will be still possible, but you may encounter strange display artefacts like destroyed dialog borders or unreadable non-ascii characters. Establishing a connection with the installation system is as simple as typing:

$ ssh -l installer install_host

Whereinstall_hostis either the name or IP address of the computer being installed. Before the actual login the fingerprint of the remote system will be displayed and you will have to confirm that it is correct.

Note:Thesshserver in the installer uses a default configuration that does not send keep-alive packets. In principle, a connection to the system being installed should be kept open indefinitely.

However, in some situations — depending on your local network setup — the connection may be lost after some period of inactivity. One common case where this can happen is when there is some form of Network Address Translation (NAT) somewhere between the client and the system being installed. Depending on at which point of the installation the connection was lost, you may or may not be able to resume the installation after reconnecting.

You may be able to avoid the connection being dropped by adding the option -o ServerAliveInterval=valuewhen starting thesshconnection, or by adding that option in yoursshconfiguration file. Note however that in some cases adding this option may alsocause a connection to be dropped (for example if keep-alive packets are sent during a brief network outage, from which ssh would otherwise have recovered), so it should only be used when needed.

Note: If you install several computers in turn and they happen to have the same IP address or hostname, sshwill refuse to connect to such host. The reason is that it will have different fingerprint, which is usually a sign of a spoofing attack. If you are sure this is not the case, you will need to delete the relevant line from~/.ssh/known_hosts¹¹and try again.

After the login you will be presented with an initial screen where you have two possibilities called Start menu and Start shell. The former brings you to the main installer menu, where you can continue with the installation as usual. The latter starts a shell from which you can examine and possibly fix the remote system. You should only start one SSH session for the installation menu, but may start multiple sessions for shells.

Warning

After you have started the installation remotely over SSH, you should not go back to the installation session running on the local console. Doing so may corrupt the database that holds the configuration of the new system. This in turn may result in a failed installation or problems with the installed system.

Chapter 7. Booting Into Your New Ubuntu System

7.1. The Moment of Truth

Your system’s first boot on its own power is what electrical engineers call the “smoke test”.

If the system fails to start up correctly, don’t panic. If the installation was successful, chances are good that there is only a relatively minor problem that is preventing the system from booting Ubuntu. In most cases such problems can be fixed without having to repeat the installation. One available option to fix boot problems is to use the installer’s built-in rescue mode (seeSection 8.7).

7.2. Mounting encrypted volumes

If you created encrypted volumes during the installation and assigned them mount points, you will be asked to enter the passphrase for each of these volumes during the boot.

For partitions encrypted using dm-crypt you will be shown the following prompt during the boot:

Starting early crypto disks... part_crypt(starting) Enter LUKS passphrase:

In the first line of the prompt,^partis the name of the underlying partition, e.g. sda2 or md0. You are now probably wonderingfor which volumeyou are actually entering the passphrase. Does it relate to your^/home? Or to^/var? Of course, if you have just one encrypted volume, this is easy and you can just enter the passphrase you used when setting up this volume. If you set up more than one encrypted volume during the installation, the notes you wrote down as the last step inSection 6.3.3.6come in handy. If you did not make a note of the mapping between^part_cryptand the mount points before, you can still find it in/etc/crypttaband^/etc/fstabof your new system.

The prompt may look somewhat different when an encrypted root file system is mounted. This de-pends on which initramfs generator was used to generate the initrd used to boot the system. The example below is for an initrd generated usinginitramfs-tools:

Begin: Mounting root file system... ...

Begin: Running /scripts/local-top ...

Enter LUKS passphrase:

No characters (even asterisks) will be shown while entering the passphrase. If you enter the wrong passphrase, you have two more tries to correct it. After the third try the boot process will skip this volume and continue to mount the next filesystem. Please seeSection 7.2.1for further information.

After entering all passphrases the boot should continue as usual.

7.2.1. Troubleshooting

If some of the encrypted volumes could not be mounted because a wrong passphrase was entered, you will have to mount them manually after the boot. There are several cases.