Debian Server Post-Installation Script

Automates system configuration, hardening, and tooling setup for Debian servers with profile-based defaults and safe security configurations.

Designed for Debian Server, but compatible with Ubuntu Server distributions.
For Ubuntu Desktop, see: github.com/franckferman/ubuntu-post-install

Features

Profile-based configuration for different deployment scenarios
VPS-safe security hardening to prevent remote lockouts
Modular network hardening with 9 configurable components
Multiple firewall engines: UFW, nftables, iptables
Customizable service and package hardening
Secure defaults that preserve functionality
Proxmox and Docker compatibility
APT packages with specialized tool integration

Quick Start

Download and Run

# Download script
curl -O https://raw.githubusercontent.com/franckferman/debian-server-post-install/main/debian-server-post-install.sh
chmod +x debian-server-post-install.sh

# Or direct execution (basic profile only - review first!)
curl -fsSL https://raw.githubusercontent.com/franckferman/debian-server-post-install/main/debian-server-post-install.sh | bash

# For root users (add --allow-root)
./debian-server-post-install.sh --allow-root

# Direct with arguments (download first)
curl -fsSL https://raw.githubusercontent.com/franckferman/debian-server-post-install/main/debian-server-post-install.sh | bash -s -- --server-profile dev

Profile Examples

# Basic installation (VPS-safe, no Docker)
./debian-server-post-install.sh

# Production server with Docker
./debian-server-post-install.sh --server-profile prod

# Development server with full stack
./debian-server-post-install.sh --server-profile dev

# Maximum security (still VPS-safe)
./debian-server-post-install.sh --server-profile hardened

# Default + Docker installation
./debian-server-post-install.sh --install-docker        # docker.io (default)
./debian-server-post-install.sh --docker-type io        # docker.io (explicit)
./debian-server-post-install.sh --docker-type ce        # docker-ce (official)

# Examples with different types
./debian-server-post-install.sh --server-profile default --docker-type ce
./debian-server-post-install.sh --server-profile default --install-docker

Server Profiles

`--server-profile <profile>`

Profile	Editor	Firewall	VIM	SSH	Apps	Use Case
default	both	ufw + hardened	minimal	VPS-safe	server (37)	General purpose
prod	both	nftables + hardened	minimal	VPS-safe	server (37)	Production ready
dev	both	ufw + transparent	full	VPS-safe	full (57)	Development friendly
minimal	vim	ufw + hardened	minimal	VPS-safe	minimal (5)	Lightweight essential
hardened	vim	nftables + hardened	bare	VPS-safe	defense (47)	Maximum security

Profile Characteristics

default - Balanced

+ Both editors (Vim + Neovim/LazyVim)
+ UFW firewall with hardened rules
+ Minimal Vim preset (stable)
+ Monitoring and logging enabled
- No Docker (use --docker-type to install)
+ Network hardening: ICMP/TCP/Source routing protection active
- Network hardening: IPv6/Anti-spoofing/Connection limits commented (safe)

prod - Production Optimized

+ nftables firewall (performance)
+ SSH hardening enabled
+ Docker + Compose
+ Enhanced monitoring/logging
+ Network hardening disabled for dev (transparent firewall)
+ All other security hardening active

dev - Development Friendly

+ UFW transparent firewall (no blocking)
+ Full Vim preset (IDE-like)
+ Nerd Fonts for terminal
+ Docker + Compose
+ Complete development stack (Node.js, Go, etc.)
- Monitoring disabled (lighter)
- Network hardening disabled (development transparent)

minimal - Lightweight

+ Vim only (no Neovim)
+ Essential tools only (5 packages)
- No Docker/monitoring
+ Essential security only
+ Same network hardening as default

hardened - Maximum Security

+ Bare Vim preset (minimal surface)
+ nftables firewall
+ USBGuard enabled
+ Defense apps profile (security tools)
- No Docker (reduced attack surface)
+ All basic hardening features active
+ Same network hardening as default (conservative)

Apps-Profile System

`--apps-profile <profile>`

The apps-profile system uses inheritance and specialized functions to minimize redundancy:

minimal (5) -> default (29) -> server (37) -> minimal-development (32) -> development (43)
                                           -> security (39) -> defense (47)
                                                           -> offsec (40)
                                                           -> full (57) -> enterprise (67)

Quick Reference Table

Profile	Packages	Inherits From	Adds	Primary Use Case
minimal	5	-	Survival only	Containers, ultra-light VPS
default	29	minimal	Comfort + infrastructure tools	Standard server
server	37	default	Server mgmt (monitoring, backup)	Production server
minimal-development	32	server	Light dev tools (python-dev, make)	Light development
development	43	minimal-development	Full stack (node, golang, docker)	Complete development
security	39	server	General security tools (nmap, tcpdump)	Network security basics
defense	47	security	Blue team tools (lynis, wireshark)	Security audit server
offsec	40	security	Red team tools (netcat)	Offensive security
full	57	development + defense	Complete dev + security	Full workstation
enterprise	67	full	Compliance (auditd, tripwire)	Enterprise compliance

Package Details by Layer

Level 1: minimal (5 packages)

git curl vim fail2ban tmux

Essential packages for remote server management.

Level 2: default (+24 packages)

# Essential tools
wget zsh htop net-tools unzip tree ncdu ss lsof
# Archive tools
lsd zip unrar p7zip-full
# Infrastructure tools
build-essential software-properties-common
apt-transport-https ca-certificates gnupg lsb-release
python3 python3-pip python3-venv jq rsync

Level 3: server (+8 packages)

logrotate psmisc dstat iotop nethogs
backup-manager sudo screen
openssl ca-certificates-utils
cron anacron at rsyslog vnstat

Level 4A: minimal-development (+5 packages)

python3-dev make cmake pkg-config
sqlite3 golang-go

Level 5A: development (+11 packages)

# Development stack
nodejs npm golang postgresql-client mysql-client
ansible-core fzf yq ripgrep autotools-dev
# Docker (conditional on --docker-type)
docker.io docker-compose  # if --docker-type io
# HashiCorp tools (via specialized function)
terraform packer vault   # via _install_hashicorp_from_profile

Level 4B: security (+2 packages)

nmap tcpdump

Level 5B: defense (+8 packages)

lynis rkhunter chkrootkit
wireshark-common tshark
aide debsecan debsums

Level 5C: offsec (+1 package)

netcat-openbsd

Level 6: enterprise (+10 packages)

auditd sysstat acct
logwatch logcheck
rng-tools haveged

Installation Methods

APT Standard Packages

Most packages are installed via standard APT repositories in step 5.

Specialized Functions

Some tools require external repositories and use specialized functions:

HashiCorp Tools (terraform, packer, vault):

Adds HashiCorp repository
Called by _install_hashicorp_from_profile() for development/full/enterprise profiles

Docker Engine:

--docker-type io: docker.io from APT (default, stable)
--docker-type ce: docker-ce from official Docker repository

Network Hardening

The script provides 9 modular network security components with individual flags. Each component can be enabled or disabled independently.

Network Security Components

Safe by Default (Enabled)

These protections target obsolete or dangerous protocols with minimal compatibility risk:

+ ICMP Redirects Protection     # Prevents redirection attacks  
+ Source Routing Protection     # Prevents source routing attacks
+ ICMP Security Protection      # Prevents smurf attacks and bogus errors
+ TCP SYN Flood Protection      # Enables SYN cookies

Conservative by Default (Disabled)

These features may impact complex network configurations:

- IPv6 Configuration           # Safe for Proxmox/Docker
- Martians Packet Logging      # Reduces log verbosity
- Anti-spoofing (rp_filter)    # Safe for VLANs/complex routing
- Connection Limits Tuning     # Safe for high-performance applications
- Modern Security Features     # Safe for forwarding-dependent services

Network Hardening Flags

IPv6 Configuration

--disable-ipv6                  # Disable IPv6 completely (default, Proxmox safe)
--no-disable-ipv6              # Enable IPv6 with security hardening

ICMP Redirects Protection

--disable-icmp-redirects        # Disable ICMP redirect protection  
--no-disable-icmp-redirects    # Enable ICMP redirect protection (default)

Source Routing Protection

--disable-source-routing        # Disable source routing protection
--no-disable-source-routing    # Enable source routing protection (default)

Martians Packet Logging

--disable-martians-logging      # Disable martians packet logging (default)
--no-disable-martians-logging  # Enable martians packet logging

ICMP Security Protection

--disable-icmp-protection       # Disable ICMP security protection
--no-disable-icmp-protection   # Enable ICMP security protection (default)

TCP SYN Flood Protection

--disable-tcp-protection        # Disable TCP security protection
--no-disable-tcp-protection    # Enable TCP security protection (default)

Anti-spoofing Protection

--disable-antispoofing          # Disable anti-spoofing protection (default)
--no-disable-antispoofing      # Enable anti-spoofing protection (rp_filter=1)

Connection Limits Tuning

--disable-connection-limits     # Disable connection limits tuning (default)
--no-disable-connection-limits # Enable TCP connection limits tuning

Modern Security Features

--disable-modern-security       # Disable modern security features (default)
--no-disable-modern-security   # Enable modern security features

Kexec System Call

--disable-kexec                # Allow kexec system call (specialized environments)
--no-disable-kexec             # Disable kexec system call (default, security hardening)

SSH Configuration

Default SSH Security

# VPS-SAFE defaults everywhere
SSH_KEY_ONLY=false        # Passwords allowed (no lockout)
DISABLE_ROOT_SSH=false    # Root SSH enabled (remote access safe)
ALLOW_SSH=true           # SSH enabled by default
SSH_PORT=22              # Standard port

SSH Hardening Flags

# Basic SSH Configuration
--allow-ssh                  # Open SSH port (default: enabled for servers)
--ssh-port <port>            # SSH port number (default: 22)
--no-ssh-hardening           # Disable SSH hardening completely

# Authentication Control
--ssh-key-only               # Disable password authentication, keys only
--disable-root-ssh           # Disable root SSH login
--no-disable-root-ssh        # Allow root SSH login (default: enabled for remote access safety)

# IPv4/IPv6 Protocol Control
--ssh-enable-ipv6            # Explicitly enable IPv6 (default: enabled)
--ssh-disable-ipv6           # Force SSH to IPv4 only (AddressFamily inet)
--ssh-enable-ipv4            # Explicitly enable IPv4 (default: enabled)  
--ssh-disable-ipv4           # Force SSH to IPv6 only (AddressFamily inet6)
--ssh-listen-address <ip>    # Bind SSH to specific IP address (can be used multiple times)

# Legacy/Modern Compatibility
--ssh-modern-only            # Remove legacy SSH options (Protocol 2, etc.)
--no-ssh-modern-only         # Keep legacy SSH compatibility (default: enabled)
--ssh-rsa                    # Enable RSA host key for legacy compatibility (default: enabled)
--no-ssh-rsa                 # Disable RSA host key for modern clients only

Firewall Configuration

Firewall Engines

--firewall <engine>
  ufw        # Simple, recommended for most servers
  nftables   # Modern, high-performance
  iptables   # Legacy but widely supported

Firewall Profiles

--firewall-profile <profile>
  hardened    # Drop all incoming, allow outgoing + established
  transparent # Allow all traffic (development/testing)

Docker Configuration

Docker Installation

--install-docker         # Force Docker installation (docker.io by default)
--docker-type <type>     # Docker type (auto-enables installation)
  io  # docker.io (Debian/Ubuntu repos, stable)
  ce  # docker-ce (Docker official repos, latest features)
--no-docker              # Skip Docker installation

Installation Logic:

default/minimal/hardened: No Docker by default
prod/dev: Docker installed automatically
Any profile: Use --install-docker, --extras docker, or --docker-type to force installation
--docker-type: Automatically enables Docker installation with specified type
--extras docker: Works with --docker-type to specify engine type

Examples:

# Default profile + Docker CE
./script.sh --server-profile default --docker-type ce
./script.sh --server-profile default --extras docker --docker-type ce

# Default profile + Docker IO  
./script.sh --server-profile default --install-docker
./script.sh --server-profile default --extras docker

Both types get identical security configuration

Editor Configuration

Editor Modes

--editor <mode>
  both     # Vim + Neovim/LazyVim (default most profiles)
  vim      # Vim only (minimal/hardened)
  neovim   # LazyVim only
  none     # Skip editor installation

Vim Presets

--vim-preset <preset>
  full     # vim-plug + plugins (dev profile)
  minimal  # gruvbox + basic config (default/prod/minimal)
  bare     # basic settings only (hardened)

Kernel Security Hardening

Standards and Sources

The kernel hardening parameters are based on industry-standard security frameworks:

Primary Sources:

CIS Benchmarks - Center for Internet Security Linux hardening guidelines
ANSSI - French National Agency for Information Systems Security
NIST SP 800-53 - National Institute of Standards and Technology controls
KSPP - Linux Kernel Self-Protection Project recommendations

Applied Protections:

# Information Disclosure Prevention (CIS 1.6.1 + ANSSI R12)
kernel.dmesg_restrict = 1              # Prevent unprivileged kernel log access
kernel.kptr_restrict = 2               # Hide kernel pointers (anti-KASLR bypass)
kernel.yama.ptrace_scope = 1           # Restrict process debugging

# Kernel Exploit Mitigation (KSPP + CIS)
kernel.kexec_load_disabled = 1         # Disable kexec (anti-rootkit)
kernel.unprivileged_bpf_disabled = 1   # Disable unprivileged eBPF
net.core.bpf_jit_harden = 2           # Harden BPF JIT compiler

# File System Security (CIS 1.6.4 + NIST)
fs.suid_dumpable = 0                   # Disable SUID core dumps
fs.protected_hardlinks = 1             # Prevent hardlink attacks
fs.protected_symlinks = 1              # Prevent symlink attacks
fs.protected_fifos = 2                 # Prevent FIFO attacks
fs.protected_regular = 2               # Prevent file attacks

# ASLR Enhancement (CIS 1.6.2 + KSPP)
kernel.randomize_va_space = 2          # Full address space randomization
vm.mmap_rnd_bits = 32                  # Maximum mmap entropy (64-bit)
vm.mmap_rnd_compat_bits = 16          # Maximum mmap entropy (32-bit)

Hardening Profiles

`--hardening-profile <profile>`

Profile	Root Lock	USB Guard	Services Removed	Packages Removed
server	- No	- No	9 services	9 packages
workstation	- No	+ Yes	7 services	9 packages
enterprise	- No	+ Yes	5 services	9 packages

Service Hardening by Profile

# server (default for all server profiles)
Removes: avahi-daemon, cups, bluetooth, whoopsie, apport, 
         speech-dispatcher, telnet, rsh-server, tftp

# workstation
Removes: avahi-daemon, cups, whoopsie, apport, 
         telnet, rsh-server, tftp

# enterprise (preserves corporate services)
Removes: whoopsie, apport, telnet, rsh-server, tftp
Keeps: avahi-daemon, cups, bluetooth (corporate compatibility)

Packages Hardening by Profile

# server/workstation/enterprise (aggressive cleanup)
Removes: xinetd, nis, rsh-client, talk, telnet, tftp,
         rsh-server, telnet-server, tftp-server

Hardening Control

Service Hardening

--harden-services              # Enable service hardening (default)
--no-harden-services           # Skip service hardening
--harden-services-list "a,b,c" # Custom service list (overrides profile)
--skip-services "x,y"          # Remove services from profile list

Package Hardening

--harden-packages              # Enable package hardening (default)
--no-harden-packages           # Skip package removal
--harden-packages-list "a,b,c" # Custom package list (overrides profile)
--skip-packages "x,y"          # Remove packages from profile list

Complete Examples

VPS Production Server (Safe + Secure)

./debian-server-post-install.sh --server-profile prod --ssh-port 2222
# → Safe network hardening enabled, IPv6/anti-spoofing disabled for compatibility

High Security Server (Expert)

./debian-server-post-install.sh \
  --server-profile hardened \
  --no-disable-ipv6 \
  --no-disable-antispoofing \
  --no-disable-martians-logging \
  --ssh-key-only --disable-root-ssh
# → Maximum network and SSH hardening

Development Server with Docker CE

./debian-server-post-install.sh \
  --server-profile dev \
  --docker-type ce \
  --install-nerd-fonts \
  --no-disable-ipv6
# → Full development stack with Docker CE

Enterprise Compliance Server

./debian-server-post-install.sh \
  --server-profile default \
  --apps-profile enterprise \
  --hardening-profile enterprise \
  --install-usbguard \
  --no-disable-antispoofing
# → Enterprise compliance tooling with USB security

Compatibility Notes

Proxmox/Virtualization

IPv6: Disabled by default (safe for clustering/VMs)
Anti-spoofing: Disabled by default (safe for VLANs/bridges)
Modern Security: Disabled by default (forwarding=0 breaks VMs)
All other hardening: Enabled and safe

Docker/Containers

Modern Security: NEVER enable (forwarding=0 breaks containers)
Anti-spoofing: May break complex networking
docker.io vs docker-ce: Both supported via --docker-type
All other hardening: Safe and recommended

VLANs/Complex Networking

Anti-spoofing: Disabled by default (rp_filter=1 breaks inter-VLAN routing)
Connection Limits: Disabled by default (may limit high-performance routing)

Configuration Matrix

All Server Profiles Configuration

Setting	default	prod	dev	minimal	hardened
EDITOR_MODE	both	both	both	vim	vim
VIM_PRESET	minimal	minimal	full	minimal	bare
FIREWALL	ufw	nftables	ufw	ufw	nftables
FIREWALL_PROFILE	hardened	hardened	transparent	hardened	hardened
APPS_PROFILE	server	server	full	minimal	defense
DOCKER_TYPE	io	io	io	io	io
HARDENING_PROFILE	server	server	server	server	server
HARDEN_NETWORK	true	true	false	true	true
SSH_KEY_ONLY	false	false	false	false	false
DISABLE_ROOT_SSH	false	false	false	false	false
LOCK_ROOT	false	false	false	false	false
INSTALL_USBGUARD	false	false	false	false	true

Advanced Features

Extra Software

--extras <list>            # Comma-separated extras to install
  docker                   # Enable Docker installation (use with --docker-type)
  gh                       # GitHub CLI with official repository
  hashicorp                # Redirects to apps-profile development+
  monitoring               # Handled by existing monitoring steps
  mullvad                  # Use --install-mullvad flag instead

--extra-packages <list>    # Comma-separated APT packages to add
  htop,bat,exa,fd-find     # Example: modern CLI tools

--install-mullvad          # Mullvad VPN client
--mullvad-source <method>  # Installation method (apt|direct|github)