Common Linux Server Administration Tasks: Redis Password Setup, MySQL Replication Recovery, Nginx HTTPS Redirection, Security Measures, Zabbix Monitoring, and Configuration Tips

1. Setting a password for Redis on Linux

Edit the Redis configuration file and enable the requirepass directive with your own password, then restart the service.

vim /etc/redis.conf

#requirepass foobared # remove the comment and replace foobared with your password

requirepass 123456

Restart Redis:

cd /usr/local/bin

./redis-server /etc/redis.conf

Test the connection:

./redis-cli

When prompted with (error) NOAUTH Authentication required. , authenticate:

auth 123456

2. Recovering MySQL master‑slave disconnection errors

Typical recovery steps:

slave stop;

SET GLOBAL sql_slave_skip_counter = 1;

slave start;

If a power outage caused desynchronization, extract the last bin‑log position from the master and re‑configure the slave:

mysqlbinlog mysql-bin.xxxx > binxxxx.txt

tail -n 100000 binxxxx.txt > tail-binxxxx.txt

Find the final Position value, then on the slave execute:

slave stop;

change master to master_host='ip', master_user='username', master_password='password', master_log_file='mysql-bin.xxxx', master_log_pos=xxxx;

slave start;

To skip specific errors (e.g., duplicate key, missing table), add to my.cnf :

slave-skip-errors = 1062,1032,1060

3. Redirecting Nginx port 80 to 443

Add the following to your server block:

if ($server_port = 80) {

return 301 https://$server_name$request_uri;

}

or

if ($scheme = http) {

return 301 https://$server_name$request_uri;

}

Also handle HTTP‑to‑HTTPS error:

error_page 497 https://$server_name$request_uri;

4. Responding to Linux server attacks

Identify the attack type: traffic‑based attacks can be mitigated with CDN; website defacement or malicious links can be handled with security tools such as “安全狗” or “者护卫神”. For massive DDoS, consider hardware firewalls.

Detection steps:

Use top to spot abnormal CPU/memory usage.

Inspect /var/log/secure for suspicious SSH attempts.

Run who to list logged‑in users.

Check deployed applications for known vulnerabilities.

Remediation actions:

Change all passwords immediately.

Notify network engineers to adjust firewall rules.

Enable the host firewall.

Change the default SSH port.

Close unused ports with netstat -ntlp and stop related services.

Disable unnecessary accounts in /etc/passwd .

Inspect processes with ps -ef and kill malicious ones.

Review HTTP server logs.

Use tcpdump -nn -i eth0 to capture suspicious traffic.

5. Monitoring MySQL with Zabbix

Zabbix collects metrics via its agent or SNMP and stores them in a database. Monitoring data is divided into historical tables (e.g., history_uint ) that record metric values over time.

6. Types of MySQL logs

MySQL maintains several logs:

Error log

General query log

Binary log (binlog)

Slow query log

7. Backing up MySQL without locking tables

For MyISAM, use:

mysqldump --skip-lock-tables …

For InnoDB, use a single‑transaction dump:

mysqldump --single-transaction …

8. Configuring Nginx IP‑based access control

Add the following to the location / block of the default site configuration:

allow 132.23.22.185;

deny all;

Then restart Nginx:

sudo service nginx restart

9. Defining custom error pages in Nginx

In nginx.conf , enable error interception:

fastcgi_intercept_errors on;

Define error pages inside the server block, for example:

error_page 404 = /404.htm;

Full example server configuration:

server {

listen 80;

server_name www.zhichun.com;

index index.html index.htm index.php;

error_page 404 = /404.htm;

include location.conf;

root /home/www/logs;

}

Place the custom 404 page in the site’s root directory, test the configuration with /usr/local/nginx/sbin/nginx -t , and restart if no errors are reported.