Memcached Distributed Setup on Ubuntu 24.04

Memcached itself has no cluster mode — distribution is handled by the client using consistent hashing.

Run multiple instances

memcached -d -l 192.168.1.10 -p 11211 -m 512 -t 4 -u memcache
memcached -d -l 192.168.1.11 -p 11211 -m 512 -t 4 -u memcache

Monitor Percona XtraDB Cluster on Ubuntu 24.04

Key wsrep variables

SHOW STATUS LIKE 'wsrep_%';

MySQL Backup and Restore on Ubuntu 24.04

mysqldump

# Single database
mysqldump -u root -p appdb > /backups/appdb_$(date +%F).sql

# All databases
mysqldump -u root -p --all-databases > /backups/all_$(date +%F).sql

# Compressed
mysqldump -u root -p appdb | gzip > /backups/appdb_$(date +%F).sql.g...

MySQL Primary-Replica Replication on Ubuntu 24.04

Primary: 192.168.1.10   Replica: 192.168.1.11

Primary – my.cnf

[mysqld]
server-id   = 1
log_bin     = /var/log/mysql/mysql-bin
binlog_format = ROW
binlog_expire_logs_seconds = 604800

CREATE USER 'replicator'@'192.168.1.11' IDENTIFIED WITH...

Install Ajenti

apt-get update

wget http://repo.ajenti.org/debian/key -O- | apt-key add -

echo "deb http://repo.ajenti.org/ng/debian main main ubuntu" >> /etc/apt/sources.list

apt-get update

apt-get install ajenti

service ajenti restart

Install Ajenti-v

apt-get install ajenti-v ajenti...

There are two modes when you don't want Certbot to edit your configuration:

• Standalone: replaces the webserver to respond to ACME challenges
• Webroot: needs your webserver to serve challenges from a known folder.

Webroot is better because it doesn't need to replace Nginx (to bind to port...

Nginx Load Balancing on Ubuntu 24.04

Round-robin (default)

upstream myapp {
    server 192.168.1.10:8080;
    server 192.168.1.11:8080;
    server 192.168.1.12:8080;
}
server {
    listen 80;
    server_name lb.example.com;
    location / { proxy_pass http://myapp; }
}

Least connections

upst...

Nginx Rate Limiting on Ubuntu 24.04

Define zones in http block

http {
    limit_req_zone $binary_remote_addr zone=api:10m     rate=10r/s;
    limit_req_zone $binary_remote_addr zone=login:10m   rate=5r/m;
}

Apply to locations

location /api/ {
    limit_req zone=api burst=20 nodelay;
    li...

Nginx Security Headers on Ubuntu 24.04

Create /etc/nginx/snippets/security-headers.conf

add_header X-Frame-Options            "SAMEORIGIN"                                 always;
add_header X-Content-Type-Options     "nosniff"                                    always;
add_header X-XSS-Protecti...

PHP-FPM Multiple Pools on Ubuntu 24.04

Pool directory: /etc/php/8.3/fpm/pool.d/

Create /etc/php/8.3/fpm/pool.d/site1.conf

[site1]
user  = site1
group = site1
listen = /run/php-fpm/site1.sock
listen.owner = www-data
listen.group = www-data
listen.mode  = 0660
pm = dynamic
pm.max_children...

Update packages

sudo apt-get update

Install nginx

sudo apt-get install -y nginx

Enable and start nginx

sudo systemctl enable nginx && systemctl start nginx

Install PHP8.1 and PHP8.1-FPM + some important modules

sudo apt-get install php8.1-cli php8.1-fpm php8.1-curl php8.1-gd php8.1-mys...

PostgreSQL Backup and Restore on Ubuntu 24.04

Logical – pg_dump

# Single database
sudo -u postgres pg_dump -Fc appdb > /backups/appdb_$(date +%F).dump

# All databases
sudo -u postgres pg_dumpall > /backups/all_$(date +%F).sql

Restore

sudo -u postgres pg_restore -d appdb /backups/appdb_2026-...

PostgreSQL Streaming Replication on Ubuntu 24.04

Primary: 192.168.1.10   Standby: 192.168.1.11

Primary – /etc/postgresql/16/main/postgresql.conf

wal_level = replica
max_wal_senders = 5
wal_keep_size = 512MB
listen_addresses = '*'

/etc/postgresql/16/main/pg_hba.conf:

host replication r...

PostgreSQL User and Role Management on Ubuntu 24.04

Create roles

CREATE ROLE alice WITH LOGIN PASSWORD 'AlicePass!';
CREATE ROLE dbadmin WITH SUPERUSER LOGIN PASSWORD 'AdminPass!';
CREATE ROLE readonly;

Grant privileges

GRANT CONNECT ON DATABASE appdb TO alice;
GRANT USAGE ON SCHEMA public T...

Install pure-ftp

apt-get update
apt-get install pure-ftpd

Ensure File /etc/inetd.conf has ftp commented out File /etc/default/pure-ftpd-common STANDALONE_OR_INETD=standalone

Add ftp users group

groupadd ftpusers

Add ftp user - ftpuser or any other id as preferred

useradd -g ftpusers -d...

Redis Cluster on Ubuntu 24.04

Minimum 3 primaries + 3 replicas (6 nodes). This example uses ports 7000-7005 on localhost.

Step 1 – Create node configs

for port in 7000 7001 7002 7003 7004 7005; do
    mkdir -p /etc/redis/cluster/$port /var/lib/redis/$port
    cat > /etc/redis/cluster/$port/red...

Redis Persistence on Ubuntu 24.04

RDB snapshots (redis.conf)

save 900 1
save 300 10
save 60 10000
dbfilename  dump.rdb
dir         /var/lib/redis
rdbcompression yes
rdbchecksum    yes

AOF (Append-Only File)

appendonly           yes
appendfilename       "appendonly.aof"
appendfsync...

Redis Sentinel (HA) on Ubuntu 24.04

Architecture

• Primary 192.168.1.10:6379
• Replica 192.168.1.11:6379, 192.168.1.12:6379
• Sentinels on port 26379 (all 3 nodes)

Primary redis.conf

bind 0.0.0.0
requirepass RedisPass!

Replica redis.conf

bind 0.0.0.0
requirepass RedisPass!
replicaof...

Secure MySQL on Ubuntu 24.04

Step 1 – Run mysql_secure_installation

mysql_secure_installation

Set root password, remove anonymous users, disallow remote root login, remove test DB.

Step 2 – Bind to localhost

[mysqld]
bind-address = 127.0.0.1

Step 3 – Audit users

SELECT User, Host, plug...

SSH Key-Based Authentication on Ubuntu 24.04

Generate key pair (client)

ssh-keygen -t ed25519 -C "[email protected]"

Copy public key to server

ssh-copy-id -i ~/.ssh/id_ed25519.pub [email protected]

Or manually:

cat ~/.ssh/id_ed25519.pub | ssh user@server \
    "mkdir -p ~/.ssh...

SSH TOTP MFA on Ubuntu 24.04

Step 1 – Install PAM module

apt install -y libpam-google-authenticator

Step 2 – Configure for each user

google-authenticator
# time-based: y, update file: y, disallow reuse: y, rate limit: y

Scan QR code with an authenticator app (Aegis, Google Authenticator, e...

Tune MariaDB Performance on Ubuntu 24.04

my.cnf

[mysqld]
innodb_buffer_pool_size        = 4G
innodb_buffer_pool_instances   = 4
innodb_log_file_size           = 512M
innodb_flush_log_at_trx_commit = 1
innodb_flush_method            = O_DIRECT

# Thread pool (MariaDB-specific)
thread_handling...

Tune MySQL Performance on Ubuntu 24.04

my.cnf

[mysqld]
innodb_buffer_pool_size        = 4G
innodb_buffer_pool_instances   = 4
innodb_log_file_size           = 512M
innodb_flush_log_at_trx_commit = 1
innodb_flush_method            = O_DIRECT
max_connections                = 200
thread_cache_size...

Tune PHP OPcache on Ubuntu 24.04

Edit /etc/php/8.3/fpm/conf.d/10-opcache.ini

opcache.enable=1
opcache.enable_cli=0
opcache.memory_consumption=256
opcache.interned_strings_buffer=16
opcache.max_accelerated_files=20000
opcache.revalidate_freq=60
opcache.validate_timestamps=1
; JIT (PHP 8.x)
opcac...