ncae-2025

Scripts for NCAE Cyber Games 2025

1 First steps

1.1 Change to root user (will prevent GUI login):

sudo su -l
passwd
apt uninstall sudo # or whichever package manager

1.2 IP address configuration

1.2.1 Kali

1.2.1.1 Edit /etc/network/interfaces:

auto eth0
iface eth0 inet static
address 192.168.13.x
netmask 255.255.255.0
gateway 192.168.13.1

1.2.1.2 Edit: /etc/resolv.conf:

nameserver 192.168.13.12

1.2.1.3 Restart networking service:

systemctl restart networking.service

1.2.2 Ubuntu

1.2.2.1 Edit /etc/netplan/01-network-manager-all.yaml:

network:
  # ...
  ethernets:
    ens18:
      dhcp4: false
      addresses:
        - 192.168.13.x/24
      gateway4: 192.168.13.1
      nameservers:
        addresses:
        - 192.168.13.12

1.2.2.2 Apply network settings:

netplan apply

1.2.3 CentOS

1.2.3.1 Edit /etc/sysconfig/network-scripts/ifcfg-eth0:

# ...
BOOTPROTO=none
IPADDR=192.168.13.x
PREFIX=24
GATEWAY=192.168.13.1
DNS1=192.168.13.12

1.2.3.2 Restart networking service:

nmcli connection reload
nmcli connection up eth0

1.3 Clone this repository:

git clone https://github.com/Liassica/ncae-2025

1.4 Setup firewall

1.4.1 Generic setup:

./ncae-2025/scripts/iptables

1.4.2 Extra ports, e.g. SSH (22) & web (80, 443):

./ncae-2025/scripts/iptables -s -w

2 Competition services

2.1 SSH

2.1.1 Install OpenSSH server if not already installed:

apt install openssh-server # w/e PM, may be just 'openssh' dep on distro

2.1.2 Configure server by editing /etc/ssh/sshd_config

The comments aren't necessary in the real config:

echo "# Force key login
PasswordAuthentication no
AuthenticationMethods publickey

# Disable root SSH access
PermitRootLogin no

# Use root-configured authorized keys
AuthorizedKeysFile /etc/ssh/authorized_keys.d/%u" >> /etc/ssh/sshd_config

2.1.3 Set up authorized users

For each scoring user, place their public SSH key in /etc/ssh/authorized_keys.d/<user>:

./ncae-2025/scripts/ssh

2.1.4 Start/restart service:

systemctl enable --now sshd.service

systemctl restart sshd.service

2.2 Other services

See the other team members' notes and documentation :)

3 Additional hardening

3.1 Kernel hardening

3.1.1 sysctl:

./ncae-2025/scripts/sysctl

3.1.2 kernel command line:

./ncae-2025/scripts/cmdline