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Avalon (The Resistance: Avalon)

Avalon (The Resistance: Avalon) [Board Game Unboxing][Rules] Avalon KS Promo The Resistance: Avalon: Kickstarter Promo

Monday, December 24, 2018 Read

Install Font Libraries and Chinese Fonts on Linux CentOS 7

Install Font Libraries and Chinese Fonts on Linux CentOS 7 yum -y install fontconfig Now you can see the fonts and fontconfig directories under /usr/shared (they did not exist before). Before that we need to create a directory. First create /usr/shared/fonts/chinese. mkdir /usr/shared/fonts/chinese Copy the fonts you need and upload them to /usr/shared/fonts/chinese. Here I use SimSun and HeiTi (used in reports). You will see files with ttf and ttc extensions.

Tuesday, December 18, 2018 Read

What is the SHA256 that comes on the sshd entry in auth.log?

What is the SHA256 that comes on the sshd entry in auth.log? ssh-keygen -lf .ssh/id_rsa.pub cat .ssh/id_rsa.pub | awk '{ print $2 }' | # Only the actual key data without prefix or comments base64 -d | # decode as base64 sha256sum | # SHA256 hash (returns hex) awk '{ print $1 }' | # only the hex data xxd -r -p | # hex to bytes base64 # encode as base64

Monday, December 17, 2018 Read

What does `< <(command args)` mean in the shell?

What does < <(command args) mean in the shell? while IFS= read -r -d $'\0' file; do dosomethingwith "$file" # do something with each file done < <(find /bar -name *foo* -print0) <() is called process substitution in the manual, and is similar to a pipe but passes an argument of the form /dev/fd/63 instead of using stdin. < reads the input from a file named on command line. Together, these two operators function exactly like a pipe, so it could be rewritten as

Saturday, November 17, 2018 Read

Netcat (Linux nc) Practical Examples for Network Admins

Netcat (Linux nc) Practical Examples for Network Admins Send a test UDP packet to a remote server This command sends a UDP test packet to the specified host and port. The -w1 option sets the timeout to 1 second. echo -n "foo" | nc -u -w1 192.168.1.8 5000 Open a UDP port to receive data nc -lu localhost 5000 Port scanning on a remote host This command scans TCP ports in the ranges 1-1000 and 2000-3000 on the specified host to see which ports are open.

Friday, November 9, 2018 Read

vimrc Configuration Guide

vimrc Configuration Guide :set nu Show line numbers: useful for debugging. :set ai Auto-indent: if the previous line has two tab widths, pressing Enter keeps those two tab widths on the next line. :set cursorline Cursor line: underline the current line to help locate the cursor. :set bg=light Color scheme for light backgrounds. The default assumes a light background (white, etc), but if your terminal background is dark purple, text may disappear (for example, comments in dark blue). Change this to :set bg=dark. :set tabstop=4

Saturday, November 3, 2018 Read

Why do browser user-agent strings always include Mozilla/5.0?

Why do browser user-agent strings always include Mozilla/5.0? What does “Mozilla/5.0” in user agent string signify? History of the browser user-agent string Quick answer Because website developers may output special features when they detect a browser (Mozilla in this case). When other browsers also support those good features, they try to mimic Mozilla so the site outputs the same content instead of a degraded version.

Wednesday, October 17, 2018 Read

Simulate Network Anomalies with TC and Netem

Simulate Network Anomalies with TC and Netem Netem and TC brief overview Netem is a network emulation module provided by Linux 2.6 and later kernels. It can be used on a good LAN to simulate complex Internet transmission performance, such as low bandwidth, latency, packet loss, and so on. Many Linux distributions with kernel 2.6+ enable this module by default, such as Fedora, Ubuntu, Redhat, OpenSuse, CentOS, Debian, etc. TC is a user-space tool in Linux, short for Traffic Control. TC controls the operating mode of the Netem module. In other words, to use Netem you need at least two conditions: the Netem module must be enabled in the kernel, and the corresponding user-space tool TC must be available.

Saturday, September 15, 2018 Read

Quagga Routing - Install, Configure and setup BGP

Tuesday, August 14, 2018 Read

Systemd Tutorial: Practical Part

Systemd Tutorial: Practical Part $ systemctl cat sshd.service [Unit] Description=OpenSSH server daemon Documentation=man:sshd(8) man:sshd_config(5) After=network.target sshd-keygen.service Wants=sshd-keygen.service [Service] EnvironmentFile=/etc/sysconfig/sshd ExecStart=/usr/sbin/sshd -D $OPTIONS ExecReload=/bin/kill -HUP $MAINPID Type=simple KillMode=process Restart=on-failure RestartSec=42s [Install] WantedBy=multi-user.target [Unit] Section: Startup Order and Dependencies After field: if network.target or sshd-keygen.service needs to start, then sshd.service should start after them. Correspondingly, the Before field defines which services sshd.service should start before. Note that After and Before only involve startup order, not dependency relationships.

Thursday, August 9, 2018 Read

RAID10 Total Failure: Mirror Drives in the Same Group Failed Together

RAID10 Total Failure: Mirror Drives in the Same Group Failed Together RAID

Wednesday, August 1, 2018 Read

Fighting DDoS: nginx, iptables, and fail2ban

Friday, July 20, 2018 Read