fail2ban (CentOS 8)

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Nov 302020
 

Install Fail2Ban and configure some default settings:

sudo yum update
sudo yum install epel-release
sudo yum install fail2ban
sudo nano /etc/fail2ban/jail.local

A typical template for jail.local looks like this:

[DEFAULT]
bantime = 43200
findtime = 600
maxretry = 3
banaction = iptables-multiport
backend = systemd

[sshd]
enabled = true

ignore = a list of I.P address that you do not wish to ban

bantime (seconds) – typical values are:
3600 (1 hour); 10800 (3 hours); 21600 (6 hours)
43200 (12 hours); 86400 (24 hours)

maxretry is the number of failures before a host is banned. Default value is 3.

findtime (seconds) and maxretry are related. Combined, they dictate the number of attempts (maxretry) within a given timeframe (findtime) which results in a ban. Default value of findtime is 600, which means that when fail2ban counts 3 failed attempts, within the last 10 minutes, it will ban the querying IP address.

Good values for findtime are:
300 or 600 (300 seconds = 5 minutes, 600 = 10 minutes)
3 for maxretry

Enable Fail2Ban at reboot, start the service, and check status:

systemctl start fail2ban
systemctl enable fail2ban
systemctl status fail2ban
fail2ban-client status
fail2ban-client status sshd

CentOs 7 – network basics

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Feb 212018
 

* Confirm NIC id/link speed info:

dmesg | grep -i duplex

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* ** To add – how to configure network settings from command line/minimum install only * ***

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* Use iPERF for ‘real world’ connection stats:

yum install iperf

Place one PC in server mode:

iperf -s

On client PC:

iperf -c <ip.address.of.server>

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Enabling TRIM support on SSDs

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May 262017
  
CentOS 7:

https://bashtheshell.github.io/guide/ssd-trim-on-centos-7/

 

Windows 7:

Enabled by default but can be confirmed via elevated command prompt and:

fsutil behavior query disabledeletenotify

DisableDeleteNotify = 1 = TRIM support disabled
DisableDeleteNotify = 0 = TRIM support enabled

To enable trim, issue:

fsutil behavior set disabledeletenotify 0

 

Mac OS X:

Enabled by default on Apple provided SSDs.
Requires enabling on third-party provided SSDs.

To confirm via the terminal, issue:

system_profiler SPSerialATADataType | grep 'TRIM'

Enable TRIM via terminal, with this command:

sudo trimforce enable

Follow the on-screen advice.

For reference, Third-party solutions include Cindori TrimEnabler, which were
a workaround when Apple temporarily disabled default trim support
for non-Apple SSDs.