DigitalOcean ubuntu 14.04 server configuration script.

init.sh

#!/bin/bash

username="ubuntu"
ssh_pub_key=""

# Setup user
adduser $username
usermod -a -G sudo $username
sudo mkdir -p "/home/${username}/.ssh"
sudo echo "${ssh_pub_key}" > "/home/${username}/.ssh/authorized_keys"
sudo chmod 700 "/home/${username}/.ssh"
sudo chmod 600 "/home/${username}/.ssh/authorized_keys"
sudo chown -R "${username}:${username}" "/home/${username}/.ssh"

# update software repository server
sudo apt-get update -y

sudo apt-get install -y python-software-properties
sudo add-apt-repository -y ppa:keithw/mosh
sudo apt-get update -y
sudo apt-get install -y mosh

# firewall via iptables
sudo iptables -A INPUT -m conntrack --ctstate ESTABLISHED,RELATED -j ACCEPT
sudo iptables -A INPUT -p udp --dport 60000:61000 -j ACCEPT
sudo iptables -A INPUT -p tcp --dport 22 -j ACCEPT
sudo iptables -I INPUT 1 -i lo -j ACCEPT
sudo iptables -P INPUT DROP
sudo ip6tables -A INPUT -m conntrack --ctstate ESTABLISHED,RELATED -j ACCEPT
sudo ip6tables -I INPUT 1 -i lo -j ACCEPT
sudo ip6tables -P INPUT DROP
echo iptables-persistent iptables-persistent/autosave_v4 boolean true | sudo debconf-set-selections
echo iptables-persistent iptables-persistent/autosave_v6 boolean true | sudo debconf-set-selections
sudo apt-get install -y iptables-persistent

# fail2ban
sudo apt-get install -y fail2ban
sudo cp /etc/fail2ban/jail.conf /etc/fail2ban/jail.local

# configure sshd
sshd_config="# Package generated configuration file
# See the sshd_config(5) manpage for details

# What ports, IPs and protocols we listen for
Port 22
# Use these options to restrict which interfaces/protocols sshd will bind to
#ListenAddress ::
#ListenAddress 0.0.0.0
Protocol 2
# HostKeys for protocol version 2
HostKey /etc/ssh/ssh_host_rsa_key
HostKey /etc/ssh/ssh_host_dsa_key
HostKey /etc/ssh/ssh_host_ecdsa_key
#Privilege Separation is turned on for security
UsePrivilegeSeparation yes

# Lifetime and size of ephemeral version 1 server key
KeyRegenerationInterval 3600
ServerKeyBits 1024

# Logging
SyslogFacility AUTH
# LogLevel INFO
LogLevel VERBOSE

# Authentication:
LoginGraceTime 120
#PermitRootLogin yes
PermitRootLogin no
StrictModes yes

RSAAuthentication yes
PubkeyAuthentication yes
#AuthorizedKeysFile	%h/.ssh/authorized_keys

# Don't read the user's ~/.rhosts and ~/.shosts files
IgnoreRhosts yes
# For this to work you will also need host keys in /etc/ssh_known_hosts
RhostsRSAAuthentication no
# similar for protocol version 2
HostbasedAuthentication no
# Uncomment if you don't trust ~/.ssh/known_hosts for RhostsRSAAuthentication
#IgnoreUserKnownHosts yes

# To enable empty passwords, change to yes (NOT RECOMMENDED)
PermitEmptyPasswords no

# Change to yes to enable challenge-response passwords (beware issues with
# some PAM modules and threads)
ChallengeResponseAuthentication no

# Change to no to disable tunnelled clear text passwords
#PasswordAuthentication yes
PasswordAuthentication no

# Kerberos options
#KerberosAuthentication no
#KerberosGetAFSToken no
#KerberosOrLocalPasswd yes
#KerberosTicketCleanup yes

# GSSAPI options
#GSSAPIAuthentication no
#GSSAPICleanupCredentials yes

# X11Forwarding yes
X11Forwarding no
X11DisplayOffset 10
PrintMotd no
PrintLastLog yes
TCPKeepAlive yes
#UseLogin no

#MaxStartups 10:30:60
#Banner /etc/issue.net

# Allow client to pass locale environment variables
AcceptEnv LANG LC_*

Subsystem sftp /usr/lib/openssh/sftp-server

# Set this to 'yes' to enable PAM authentication, account processing,
# and session processing. If this is enabled, PAM authentication will
# be allowed through the ChallengeResponseAuthentication and
# PasswordAuthentication.  Depending on your PAM configuration,
# PAM authentication via ChallengeResponseAuthentication may bypass
# the setting of \"PermitRootLogin without-password\".
# If you just want the PAM account and session checks to run without
# PAM authentication, then enable this but set PasswordAuthentication
# and ChallengeResponseAuthentication to 'no'.
UsePAM yes

# AllowUsers $username
AllowTcpForwarding no
"
sudo echo "${sshd_config}" > /etc/ssh/sshd_config
sudo service ssh restart

# update server
sudo apt-get upgrade -y