Day three: enhance SSH security in two separate phases. Closes #3

day3_geninventory_phase1.sh

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+#
+#   Day 3 - Generate Inventory (Phase 1: tachyon user)
+#   Requires linode-cli to be installed (`pip3 install linode-cli`)
+#   The hosts file generated requires ansible (`pip3 install ansible`)
+#   This will crush any ansible.cfg and hosts files in the current directory.
+
+# Default ansible group and linode label
+if [ -z "$CATEGORY" ]
+then
+    CATEGORY="UpskillChallengeNode"
+fi
+
+if [ -z "$ADMINUSER" ]
+then
+    ADMINUSER="tachyon"
+fi
+
+# fetch IP address from Linode. Assumes one device (TODO: handle a swarm of them).
+NODEIP=$(linode-cli linodes list --format 'ipv4' --label "$CATEGORY" --text | tail -n 1)
+
+# create or clobber hosts file
+cat > hosts << EOF
+[$CATEGORY]
+$NODEIP   ansible_user=$ADMINUSER 
+
+[$CATEGORY:vars]
+ansible_ssh_user=$ADMINUSER
+ansible_become=yes
+ansible_become_user=root
+ansible_become_method=sudo
+EOF
+
+# create or clobber hosts file
+cat > ansible.cfg << EOF
+[defaults]
+inventory = $(pwd)/hosts
+EOF
+
+ansible "$CATEGORY" -m ping

day3_geninventory_phase2.sh

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+#
+#   Day 3 - Generate Inventory (Phase 2: tachyon user on obscure port)
+#   Requires linode-cli to be installed (`pip3 install linode-cli`)
+#   The hosts file generated requires ansible (`pip3 install ansible`)
+#   This will crush any ansible.cfg and hosts files in the current directory.
+
+# Default ansible group and linode label
+if [ -z "$CATEGORY" ]
+then
+    CATEGORY="UpskillChallengeNode"
+fi
+
+if [ -z "$ADMINUSER" ]
+then
+    ADMINUSER="tachyon"
+fi
+
+if [ -z "$NODESSHPORT" ]
+then
+    NODESSHPORT=22022
+fi
+
+# fetch IP address from Linode. Assumes one device (TODO: handle a swarm of them).
+NODEIP=$(linode-cli linodes list --format 'ipv4' --label "$CATEGORY" --text | tail -n 1)
+
+# create or clobber hosts file
+cat > hosts << EOF
+[$CATEGORY]
+$NODEIP:$NODESSHPORT   ansible_user=$ADMINUSER 
+
+[$CATEGORY:vars]
+ansible_ssh_user=$ADMINUSER
+ansible_become=yes
+ansible_become_user=root
+ansible_become_method=sudo
+EOF
+
+# create or clobber hosts file
+cat > ansible.cfg << EOF
+[defaults]
+inventory = $(pwd)/hosts
+EOF
+
+ansible "$CATEGORY" -m ping

phase1user.yml

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+---
+- name: Create admin user
+  hosts: UpskillChallengeNode
+
+  vars:
+    newusername: "tachyon"
+
+  vars_prompt:
+    - name: "passhash"
+      prompt: "Password for the user account"
+      private: yes
+      encrypt: "sha512_crypt"
+      confirm: yes
+
+  tasks:
+  - name: install sudo
+    ansible.builtin.apt:
+      package: sudo
+      state: present
+
+  - name: create user
+    ansible.builtin.user:
+      name: "{{ newusername }}"
+      password: "{{ passhash }}"
+      groups:
+       - sudo
+      state: present
+      shell: /bin/bash
+      createhome: yes
+
+  - name: set public key authentication
+    ansible.posix.authorized_key:
+      user: "{{ newusername }}"
+      key: ssh-rsa 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 john@arecibo
+
+
+  - name: grant {{ newusername }} passwordless sudo access
+    ansible.builtin.lineinfile:
+      path: /etc/sudoers
+      regexp: '^%sudo'
+      line: "%sudo  ALL=(ALL:ALL) NOPASSWD: ALL"
+      validate: 'visudo -cf %s'
+
+
+

phase2user.yml

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+---
+- name: Lock down root & SSH on the server
+  hosts: UpskillChallengeNode
+
+  tasks:
+  - name: Disable root login over ssh
+    ansible.builtin.lineinfile:
+      path: /etc/ssh/sshd_config
+      regexp: '^PermitRootLogin'
+      line: 'PermitRootLogin no'
+
+  - name: Disable all users' password login
+    ansible.builtin.lineinfile:
+      path: /etc/ssh/sshd_config
+      regexp: '^PasswordAuthentication'
+      line: 'PasswordAuthentication no'
+
+  - name: Change SSH port
+    ansible.builtin.lineinfile:
+      path: /etc/ssh/sshd_config
+      regexp: '^#?Port '
+      line: 'Port 22022'
+
+  - name: update and upgrade packages
+    ansible.builtin.apt:
+      update_cache: yes
+      upgrade: yes
+
+  - name: install fail2ban
+    ansible.builtin.apt:
+      package: fail2ban
+      state: present
+
+  - name: restart ssh
+    service:
+      name: ssh
+      state: restarted
+