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centos 72 -- apache2 with virtual hosts -- sftp key-ed access

part2: operating system

  1. setup CentOS72
    • using virtualbox on host rohtang
    • configuring virtual machine
      1GB RAM // 1CPU + PAE/NX + VT-x/AMD-V + Nested Paging // i/o APIC // CLOCK UTC
      12MB display RAM
      28GB sata disk (host i/o cache)
      Network on vboxnet0 base-MAC: 080027472FFF
      machine01 will be 080027472F01
      machine02 will be 080027472F02
    • using ISO-image: CentOS-7-x86_64-NetInstall-1511.iso
      we get the following when booting:
    • in order to install in non-graphical mode,
      we press <TAB>
      and we add the parameter text


    • now we get this confusing user interface (did they copy fdisk from 1977?)


    • we enter the network in ipv6 only
      gateway = rohtang (prefix::2)
      dns = google (2001:4860:4860::8888)
      ipv6 = prefix::1100
    • time servers: (2017)
    • installation source is most difficult, we got stuck trying to use belnet, but it did not work, however we find the following

      (dit werkt ook in 2017 for centOS74: http://ftp.belnet.be/mirror/ftp.centos.org/7.4.1708/os/x86_64/ )

    • we select minimal install
    • we configure one user who will be administrator of all virtual machines, and a root account with a basic password;
    • we select standard but automatic MBR disk-layout which will later look like this:
      Device Boot      Start         End      Blocks   Id  System
      /dev/sda1   *        2048     1026047      512000   83  Linux
      /dev/sda2         1026048     5222399     2098176   82  Linux swap
      /dev/sda3         5222400    58720255    26748928   83  Linux
      /dev/sda3 on /     type xfs (rw,relatime,seclabel,attr2,inode64,noquota)
      /dev/sda1 on /boot type xfs (rw,relatime,seclabel,attr2,inode64,noquota)

      ... much later after correctly entering all parameters ...

    • the system gets installed, and reboots when done ...
    • after reboot we have a very basic machine without ifconfig or dig or route, but fortunately, the ip command, and almost everything else works:


  2. basic configuration
    The system has no editor at all, we install nano
    sudo yum install nano
    Since we will use ipv6 and only ipv6 we set parameter NETWORKING_IPV6 in the file /etc/sysconfig/network.
    When later removing it, everything still works, so it is not necessary. We just need patience: once the system is visibly up we still have to wait about a minute before we can connect. The above parameter and snippet below, doesn't change that.
    $ cat /etc/sysconfig/network
    # Created by anaconda


  3. cloning
    We have to set MAC-address in virtualbox -- we do a manual edit: the MAC-address ends in the student's machine-number: 08:00:27:47:2f:18
    We then set IPv6-address and hostname in the clone:
    The network configuration looks like this after correcting the IPV6ADDR:
    $ cat /etc/sysconfig/network-scripts/ifcfg-enp0s3 

    in IPV6ADDR=2a01:4f8:202:6116:1000::1118/68 the number 18 signifies the 18th clone.
    Finally we set /etc/hostname and /etc/hosts

    [user@centos72-s18 ~]$ cat /etc/hostname
    [user@centos72-s18 ~]$ cat /etc/hosts   localhost centos72-s18
    ::1         localhost centos72-s18

    .. and we restart the system to test everything.
    The product that the students will have to work with is now finished and ready to be deformed.

  4. routing
    On rohtang ports are opened to connect using ipv4 with these ipv6 machines:
    iptables -vA INPUT -p TCP --dport 61824 -j ACCEPT
    socat TCP4-LISTEN:61824,fork,su=nobody TCP6:[2a01:4f8:202:6116:1000::1118]:22 &


  5. users
    A sudo account is made on each machine with the first name of the student that will be using it. A random password containing at least 16 characters will be provided.
    The sudo-group is called wheel in centOS72. Using usermod we can add any user in this group as follows:
    $ sudo usermod -G -a wheel user
    It would be interesting to create a script for the final configuration of all machines, based on the MAC-address, which ends in the student's number: 08:00:27:47:2f:18
  6. personal configuration
    From here, the exercise starts. I get the same machine for my own 'exam', and I will install some basic utilities like vim, mc, ifconfig and the like ...
    Before doing this, however, it is time to take a snapshot.
    Next ...
    sudo yum install vim
    sudo yum install mc
    sudo yum install net-tools
    sudo yum install bind-utils