2. Self-Hosted server

Настройка и обслуживание собственного сервера

Ubuntu server first steps

Client: Generate keys

This command generate a two files with private and public keys. The public-key file will end with .pub extention, a private key file has no extention

ssh-keygen

Public key you may share with everyone, but private key must be keep in secret.

Client: Share key (publish)

You need to share you public key with target machine (server).

Best way for Ubuntu is add public key to github ssh keys, then it will be avaidable at github.com/<username>.keys

Server: Install Ubuntu-server

Becouse you install a server version, the common way to interact is remote control (.ssh), but you need to create base authorization method via physical terminal. The public key made for this purpose, but type public key by hands is takes too long, so we were publish our public key with entire ethernet at github.com/<username>.keys

While install, select import identity and enter GitHub user name. Ubuntu will automaticaly read public key and save it.

It's strongly recommended use only ssh-keys and disable password authentification.

Connect

For connect from client use this command to connect:

ssh -i ~/.ssh/some_server_name username@my.domain.com -p 22

where -i is identity path (private key path), where ~ - is home client user directory.

where -p is target port (default: 22)

where username - remote username (you enter while install)

where my.domain.com - ip of target machine or domain name

First connection from clinet to server must be as created user (not root).

If connection sucseeded and keys are valid, system ask you to add connection to known_hosts, type yes.

In case of server system reinstall old clients may see message, thats says that identity is changed. This problem rised becouse server keys stored on clinet machine is old. For fix this, in Windows, go to userfolder/.ssh and edit known_hosts. Delete lines associated with server. And try to connect again.

Root login

After install public key will be stored in ~/.ssh/authorized_keys

where ~ is user directory: /home/username.

For activate root, type this and enter password.

sudo su

Now you are login as root user and can go to /root/.ssh, this folder is already has authorized_keys file, but file is empty. This means that nobody can use ssh for login as root. For fix this you need to copy public key from user authorized_keys to root authorized_keys.

You may use this: (cat is print file content, >> is redirect output to new file line).

cat /home/<username>/.ssh/authorized_keys >> /root/.ssh/authorized_keys

Now you can connet via ssh as root.

Change current user password

passwd

Setup after install and connect

Extend disk space

This step may be already done while install, but if not do this:

vgdisplay
lvextend -l +100%FREE /dev/mapper/ubuntu--vg-ubuntu--lv
resize2fs /dev/mapper/ubuntu--vg-ubuntu--lv
df -h

For laptops:

Disable machine sleep if laptop lid is closed and reboot for apply changes:

sudo sh -c 'echo "HandleLidSwitch=lock" >> /etc/systemd/logind.conf' && reboot

Screensaver for you server monitor

apt install cmatrix
cmatrix -s -b

Change hostname

Check information about host:

hostnamectl

Change hostname:

sudo hostname new_hostname

Create users

useradd -m -s /bin/bash username

Cut maximum journal disk size

sudo journalctl --vacuum-size=100M

Nvidia

sudo apt-get purge nvidia-headless-no-dkms-535-server # Or your version
sudo apt-get install nvidia-driver-535 # Or your version
sudo reboot
nvidia-smi # Validate

SSH customization

Change server hostname

sudo hostnamectl set-hostname your-new-name

sudo nano /etc/hosts

Disable ssh login spam

Rename unnesessary files with @ at filename start at /etc/update-motd.d 

cd /etc/update-motd.d && for file in *; do mv "$file" "@$file"; done # Rename all files
mv @00-header 00-header

Colored root bash

Edit /root/.bashrc and replace similar liens to this (append -256 color)

# set a fancy prompt (non-color, unless we know we "want" color)
case "$TERM" in
    xterm-color|*-256color) color_prompt=yes;;
esac

Customize ssh login text

Message by SSH /etc/update-motd.d: use neofetch:

apt install neofetch -y

# Alternative
wget http://cz.archive.ubuntu.com/ubuntu/pool/universe/n/neofetch/neofetch_7.1.0-4ubuntu1_all.deb
sudo dpkg -i neofetch_7.1.0-4ubuntu1_all.deb

Add this line to /etc/update-motd.d/00-header

neofetch --config /etc/update-motd.d/config.conf --source /etc/update-motd.d/ascii_art.txt

Config example:

# See this wiki page for more info:
# https://github.com/dylanaraps/neofetch/wiki/Customizing-Info
print_info() {
    info title
    info "OS" distro

    info "Kernel" kernel

    info "Packages" packages
    info "Shell" shell
    #info "Resolution" resolution
    info "DE" de
    info "WM" wm
    info "WM Theme" wm_theme
    info "Theme" theme
    info "Icons" icons
    info "Terminal" term
    info "Terminal Font" term_font
    info underline
    info "Host" model
    info "CPU" cpu
    info "GPU" gpu

    info underline
    info "Uptime" uptime
    info "Local IP" local_ip
    info "Public IP" public_ip
    info "Users" users

    info underline
    info "Memory" memory
    #info "GPU Driver" gpu_driver  # Linux/macOS only

    info "CPU Usage" cpu_usage
    info "Disk" disk
    info "Battery" battery
    #info "Font" font
    #info "Song" song
    # [[ "$player" ]] && prin "Music Player" "$player"
    #info "Locale" locale  # This only works on glibc systems.

    #info cols
}

Send telegram message on every ssh login

Add script

Create file /etc/login-notify.sh

Modify TELEGRAM_BOT_TOKEN and TELEGRAM_SEND_TO variables. Optional set EXCLUDE_USERS for users about whom a message will not be sent.

#!/bin/sh

TELEGRAM_SEND_TO=123456789
TELEGRAM_BOT_TOKEN=123456789:someLETTERS
EXCLUDE_USERS="some_excluded_user another_excluded_user"

if ! echo "${EXCLUDE_USERS}" | grep -q "\<${PAM_USER}\>"; then
if [ "$PAM_TYPE" != "close_session" ]; then
    SSH_KEY=$(grep "Accepted publickey" /var/log/auth.log | tail -n 1 | awk '{print $NF}')
    WHERE_KEY=$(grep "found at" /var/log/auth.log | tail -n 1 | awk '{print $NF}')

    KEYS_PATH=$(echo "$WHERE_KEY" | cut -d ':' -f 1)
    KEYS_LINE=$(echo "$WHERE_KEY" | cut -d ':' -f 2)
    KEY_LINE=$(sed -n "${KEYS_LINE}p" "$KEYS_PATH")
    KEY_NAME=$(echo "$KEY_LINE" | cut -d ' ' -f 3)

    MESSAGE="Server: ${PAM_USER}@`hostname`%0ALogin: ${PAM_RHOST} ${KEY_NAME}"
    curl -s -X POST https://api.telegram.org/bot${TELEGRAM_BOT_TOKEN}/sendMessage -d chat_id=${TELEGRAM_SEND_TO} -d text="$MESSAGE" > /dev/null &
fi
fi

Modify to make it executable

chmod +x /etc/login-notify.sh

Add script to execute for every login

Do it by modifying file /etc/pam.d/sshd, just add line to end of file by echo:

echo 'session optional pam_exec.so seteuid /etc/login-notify.sh' >> /etc/pam.d/sshd

Increase a log level

Script search for fingerprint, but doesn't know witch authorized_keys file used for auth. For get authorized_keys file location, we need to print location to /var/log/auth.log

Increase log level:

echo 'LogLevel VERBOSE' >> /etc/ssh/sshd_config

Restart ssh for updated log level:

sudo systemctl restart ssh

Custom domain on Keenetic router

Инструкция работает если у вас есть белый статичный ip-адрес и свой домен

Check settings:

Setup certificate for domain

Setup proxy for subdomain

Firewall

Show listening ports

# Show all listening TCP ports with process names
sudo ss -tlnp

# Show all listening UDP ports with process names
sudo ss -ulnp

# Show both TCP and UDP listening ports
sudo ss -tulnp

Enable ssh (it it on 22 port)

sudo ufw allow ssh
sudo ufw allow OpenSSH
sudo ufw allow 22/tcp

Enable firewall

sudo ufw enable

Nginx setup

Настройка nginx

Cтатика на 443 порту

Без получения или обновления сертификатов

0. Установка nginx

sudo apt install nginx -y

1. Создать директории

mkdir -p /var/www/fake_site/html

Затем перенеси сюда файлы:

2. Конфиг nginx

Содержимое /var/www/fake_site/nginx.conf (подставь свой домен и пути к сертификатам):

server {
    listen 443 ssl;
    http2 on;
    server_name example.com;

    ssl_certificate     /путь/к/fullchain.pem;
    ssl_certificate_key /путь/к/privkey.pem;
    ssl_protocols TLSv1.2 TLSv1.3;

    root /var/www/fake_site/html;
    index index.html;

    # URL авторизации всегда отдаёт 403
    location = /api/login {
        return 403;
    }

    location / {
        try_files $uri $uri/ =404;
    }
}

Примечания:

3. Права доступа

Сертификаты читает главный процесс nginx (от root), поэтому их можно держать где угодно, включая /root. Проверь только, что приватный ключ закрыт от посторонних:

chmod 600 /путь/к/privkey.pem

Файлы сайта в /var/www доступны nginx по умолчанию — трогать права не нужно.

4. Подключить конфиг и запустить

# симлинк из общей папки в sites-enabled
ln -s /var/www/fake_site/nginx.conf /etc/nginx/sites-enabled/fake_site

# убрать дефолтный сайт, если мешает (конфликт server_name на 443)
rm -f /etc/nginx/sites-enabled/default

# проверка синтаксиса и перезагрузка
nginx -t && systemctl reload nginx

Если nginx -t ругается на open() ... failed (No such file or directory) — симлинк ведёт на несуществующий файл: проверь, что nginx.conf реально лежит по указанному пути и путь в ln -s абсолютный.

5. Проверка

# страница должна открываться
curl -skI https://твой-домен          # ожидаем HTTP/2 200

# URL авторизации всегда закрыт
curl -skI https://твой-домен/api/login # ожидаем HTTP/2 403

Если /api/login отдаёт 404 вместо 403 — конфиг не перезагружен или запрос уходит в другой server-блок. Проверь активные конфиги:

ls -l /etc/nginx/sites-enabled/

Открыть порт в файрволе (если используется ufw)

ufw allow 443/tcp