linux

Linux Releases

RHEL | Ubuntu | Debian

6.0	Squeeze	 2.6.32  -> Security until February 2016
7	Wheezy   3.2     -> Security until May 2018
8	Jessie   3.16    -> Security until April/May 2020
9	Stretch	 4.9	 -> Security until June 2022
10	Buster   4.19    -> Security until June 2024
11	Bullseye 5.10    -> Security until June 2026
12  Bookworm 6.1     -> Security until June 2028

Install

from existing: https://www.debian.org/releases/stretch/amd64/apds03.html.en

Download

Debian

https://www.debian.org/CD/live/

Ubuntu

http://ftp.sjtu.edu.cn/ubuntu-cd/

http://archive.ubuntu.com/ubuntu/dists/bionic-updates/main/installer-amd64/current/images/netboot/mini.iso ( Mirror only http://us.archive.ubuntu.com/ , need proxy, local DNS not working )

Debug: Console 4 or /var/log/syslog

Mirrors

  • https://debgen.github.io/

  • https://mirrors.tuna.tsinghua.edu.cn/help/debian/

    apt install netselect-apt && netselect-apt -c china --nonfree mv /etc/apt/sources.list /etc/apt/sources.list.ori && mv sources.list /etc/apt/

Bash

https://www.gnu.org/software/bash/manual/bash.html

url=https://raw.githubusercontent.com/fzinfz/scripts/master/init.sh # alias & functions
source /dev/stdin <<< "$(curl -sS $url)"

set
    -x                      debug
    -T                      If  set, any traps on DEBUG and RETURN are inherited
    -o functrace/errtrace

shopt [-pqsu] [-o] [optname …]
    -s: Enable (set) each optname.
    -u: Disable (unset) each optname.

shopt -s expand_aliases     # when the shell is not interactive
alias foo='...'

0: stdin; 1: stdout; 2: stderr              # File descriptor
2>&1 >/dev/null
&>/dev/null
ssh-add 2>/dev/null

https://git.savannah.gnu.org/cgit/bash.git/

tmux

ctrl+b x -> kill pane   # /usr/share/doc/tmux/examples/screen-keys.conf
cat /usr/share/doc/tmux/examples/screen-keys.conf | grep '\bbind \w'

Init

Level
Desc

0

Halt the system.

1

Single-user mode (for special administration).

2

Local Multiuser with Networking but without network service (like NFS)

3

Full Multiuser with Networking

4

Not Used

5

Full Multiuser with Networking and X Windows(GUI)

6

Reboot.

ls -R -l /etc/rc*

ls -l /usr/lib/systemd      # check `systemd` page for more
ls -l /usr/share/upstart    # last release 2014; 3 years ago
ls -l /etc/init.d           # SysV init

cat /etc/modules-load.d/*

apt install systemd-sysv    # make link: /sbin/init -> /lib/systemd/systemd

login & non-login shells

https://www.gnu.org/software/bash/manual/html_node/Bash-Startup-Files.html

login shells：  
    /etc/profile
    ~/.bash_profile(?-> ~/.bashrc), ~/.bash_login, and ~/.profile 
    exit:  ~/.bash_logout

non-login shells： 
    ~/.bashrc

# echo $0 : `shopt login_shell` \| $-
-bash : login_shell on | himBHs
# bash
# echo $0 : `shopt login_shell` \| $-
bash : login_shell off | himBHs
# bash -c 'echo $0 : `shopt login_shell` \| $-'
bash : login_shell off | hBc

supervisord

http://supervisord.org/running.html

Exit code

http://tldp.org/LDP/abs/html/exitcodes.html

1	Catchall for general errors
2	Misuse of shell builtins
126	Command invoked cannot execute
127	"command not found"	illegal_command	Possible problem with $PATH or a typo
128+n	Fatal error signal "n"	
    kill -9 $PPID of script	$? returns 137 (128 + 9)
130	Script terminated by Control-C

Syslog Message Severities

https://tools.ietf.org/html/rfc5424#section-6.2.1

0       Emergency: system is unusable
1       Alert: action must be taken immediately
2       Critical: critical conditions
3       Error: error conditions
4       Warning: warning conditions
5       Notice: normal but significant condition
6       Informational: informational messages
7       Debug: debug-level messages

Signals

kill -l
1) SIGHUP       2) SIGINT       3) SIGQUIT      4) SIGILL       5) SIGTRAP
6) SIGABRT      7) SIGBUS       8) SIGFPE       9) SIGKILL ... 64) SIGRTMAX

kill

pkill -KILL -u {username}

top

* 1 - Single Cpu       Off (thus multiple cpus)
* c - Command line     Off (name, not cmdline)
* i - Idle tasks       On  (show all tasks)
j - Str align right  Off (not right justify)
V - Forest view      On  (show as branches)
f - sort/hide columns
(`*')  could be overridden through the command-line.

Glances - A top/htop alternative - Python

https://github.com/nicolargo/glances

pip install glances[action,browser,cloud,cpuinfo,chart,docker,export,folders,gpu,ip,raid,snmp,web,wifi]

User & Permission

add user to group

sudo adduser foobar www-data
sudo usermod -a -G ftp tony

password

echo user:pwd | chpasswd

sudoers

sudo visudo
    root    ALL=(ALL) ALL # {terminals}=({users}) {commands}
    %supergroup  ALL=(ALL) NOPASSWD:ALL

chown

chown -h myuser:mygroup mysymbolic

Package Management

Redhat

Free RHEL： https://developers.redhat.com/articles/no-cost-rhel-faq/

subscription-manager register
subscription-manager attach --auto
subscription-manager repos --enable rhel-7-server-optional-rpms
subscription-manager repos --enable rhel-7-server-extras-rpms
yum install epel-release
rm -f /var/run/yum.pid <PID> && yum remove PackageKit

yum-config-manager --disable c7-media
yum --nogpgcheck localinstall xx.rpm

### EPEL
http://elrepo.org/tiki/tiki-index.php

rpm --import https://www.elrepo.org/RPM-GPG-KEY-elrepo.org
rpm -Uvh http://www.elrepo.org/elrepo-release-7.0-3.el7.elrepo.noarch.rpm
yum install yum-plugin-fastestmirror
yum --enablerepo=elrepo-kernel install kernel-ml

Ubuntu

Main - Canonical-supported free and open-source software. Universe - Community-maintained free and open-source software. Restricted - Proprietary drivers for devices. Multiverse - Software restricted by copyright or legal issues.

# https://mirror.tuna.tsinghua.edu.cn/help/ubuntu/
deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial main restricted universe multiverse

Debian

→ experimental → unstable(Sid) → testing → stable Unstable - repository where new & untested packages are introduced. Testing - repository with packages from unstable, if no bug are found within 10 days.

main consists of DFSG-compliant packages, which do not rely on software outside this area to operate. These are the only packages considered part of the Debian distribution. contrib packages contain DFSG-compliant software, but have dependencies not in main (possibly packaged for Debian in non-free). non-free contains software that does not comply with the DFSG.

deb http://mirror.sjtu.edu.cn/debian/ bullseye main contrib non-free

experimental

deb http://mirror.sjtu.edu.cn/debian/ experimental main contrib non-free

apt install -t experimental linux-image-amd64 # latest kernel

dpkg

dpkg --get-selections   # list installed

To install .deb manually, visit linux/kernel page.

apt

apt-get install linux-base -t jessie-backports
apt-cache search linux-image | grep linux-image-4
apt install linux-image-4.10.0-9-generic linux-image-extra-4.10.0-9-generic

apt show linux-image-extra-4.10*

apt-get install --only-upgrade docker-engine

apt policy docker-ce | head -n 20

apt-get autoclean
apt list --installed

rm -r /var/lib/apt/lists/*
echo 'Acquire::http::Proxy "http://192.168.88.25:7890"; ' > /etc/apt/apt.conf.d/proxy

ssh server

deb http://.../debian/ buster main contrib non-free

apt install openssh-server # not "openssl"

journalctl -u ssh # fix： ssh-rsa not in PubkeyAcceptedAlgorithms
PubkeyAcceptedAlgorithms  +ssh-rsa

Grub

grub2-mkconfig -o /boot/grub2/grub.cfg
awk -F\' '/menuentry / {print $2}' /boot/grub/grub.cfg
grub2-set-default 'CentOS Linux (4.9.0-rc8-amd64) 7 (Core)'
grub2-editenv list

fix: https://www.supergrubdisk.org/category/download/

grub-customizer

sudo add-apt-repository ppa:danielrichter2007/grub-customizer
sudo apt-get update
sudo apt-get install grub-customizer

boot .iso

https://netboot.xyz/docs/booting/grub

apt install grub-imageboot
mkdir /boot/images && cd /boot/images
wget https://boot.netboot.xyz/ipxe/netboot.xyz.iso
update-grub2

boot repair

https://sourceforge.net/p/boot-repair-cd/home/Home/ apt install linux-image-* # if vmlinuz & initrd.img missing

ubuntu

sudo add-apt-repository ppa:yannubuntu/boot-repair
sudo apt-get update
sudo apt-get install -y boot-repair && boot-repair

Serial

https://help.ubuntu.com/community/SerialConsoleHowto

GRUB_CMDLINE_LINUX="console=tty0 console=ttyS0,115200n8"

client

screen /dev/ttyUSB0 115200
picocom -b 115200 /dev/ttyUSB0

Benchmark

http://www.brendangregg.com/Perf/linux_benchmarking_tools.png

    sysbench --test=cpu --cpu-max-prime=20000 --num-threads=32 run

    wget http://www.numberworld.org/y-cruncher/y-cruncher%20v0.7.9.9510-static.tar.xz
    tar -xf y-cruncher*.tar.xz

sshd

mobaxterm login failed: No supported authentication methods

PubkeyAcceptedAlgorithms +ssh-rsa # sshd_config # journalctl -u ssh

ssh redirect

ssh -L 9000:public.com:80   # visit local:9000 -> public.com:80
ssh -L 0.0.0.0:54321:127.0.0.1:54321 remote -p 22
ssh -R 9000:localhost:3000  # visit remote:9000 -> local:3000, "GatewayPorts yes" in sshd_config
    -nNT -L ...   # port forwarding only, no shell

web

wget

wget -O diff_name.zip http://...

curl

curl -O http://...
curl -o diff_name.zip http://

curl -sSL $1

  -f, --fail          Fail silently (no output at all) on HTTP errors (H)
  -s, --silent        Silent mode (don't output anything)
  -S, --show-error    Show error. With -s, make curl show errors when they occur
  -L, --location      Follow redirects (H)
  -o, --output FILE   Write to FILE instead of stdout
  -O, --remote-name   Write output to a file named as the remote file

files

String replace: http://unix.stackexchange.com/questions/112023/how-can-i-replace-a-string-in-a-files

apt-get install mlocate
updatedb
locate -S
lsof -p <PID>

ls --help | grep -E '[-][tr]\b'
-r, --reverse              reverse order while sorting
                            extension -X, size -S, time -t, version -v
-t                         sort by modification time, newest first

mkdir -p /not/existing/folder

cat > file <<'EOL'
EOL

ncdu --exclude='/root/data/*' /

du -hcd 2  / | more
du -a / | sort -n -r | head -n 20

ls -1 $PWD | wc -l  # count files

file /bin/ps
ldd /bin/ps

find

find /home -iname tecmint.txt
find $1 -iname $2
# find . ! -readable / -writable / -executabl
# find . ! -perm -g=w

find -regextype posix-extended -regex ".*[.](py|sh)" -exec chmod +x {} \;

grep

grep --color=auto -rn -P "${regex}" ${path}
# -r, --recursive           like --directories=recurse
# -n, --line-number         print line number with output lines
# -P, --perl-regexp         PATTERN is a Perl regular expression

compress/uncompress

gunzip file.gz

tar -czvf name-of-archive.tar.gz /path/to/directory-or-file # Compress

tar -tvf my-data.tar.gz '*.py'

tar -zxvf toExtract.tar.gz
tar -xvf {tarball.tar} {special_file} -C /target/directory

tar -cf archive.tar foo bar  # Create archive.tar from files foo and bar.
tar -tvf archive.tar         # List all files in archive.tar verbosely.
tar -xf archive.tar          # Extract all files from archive.tar.
    -t, --list                 list the contents of an archive
    -j, --bzip2                filter the archive through bzip2
    -c, --create               create a new archive    
    -x, --extract, --get       extract files from an archive    
    -z, --gzip, --gunzip, --ungzip   filter the archive through gzip
    -v, --verbose              verbosely list files processed
    -f, --file=ARCHIVE         use archive file or device ARCHIVE

zip [options] zipfile files_list
    -r   recurse into directories
    -x   exclude the following names
    -v   verbose operation/print version info

    -m   move into zipfile (delete OS files) !!
    -d   delete entries in zipfile !!!
    -u   update: only changed or new files

xz --decompress file.xz # -dgrub # unxz

rsync

rsync -aP -e "ssh -p $3" $1 root@$2

rsync -aP  /root/_bin root@remote:/root
rsync -aP -e "ssh -p 10220" /local root@remote:/dir   --remove-source-files
    -v, --verbose               increase verbosity
    -a, --archive               archive mode; equals -rlptgoD (no -H,-A,-X)
        --no-OPTION             turn off an implied OPTION (e.g. --no-D)
    -r, --recursive             recurse into directories
    -l, --links                 copy symlinks as symlinks
    -p, --perms                 preserve permissions
    -o, --owner                 preserve owner (super-user only)
    -g, --group                 preserve group
    -D                          same as --devices --specials
    -t, --times                 preserve modification times
    -S, --sparse                handle sparse files efficiently
    -e, --rsh=COMMAND           specify the remote shell to use
        --partial               keep partially transferred files
        --partial-dir=DIR       put a partially transferred file into DIR
    -z, --compress              compress file data during the transfer
        --progress              show progress during transfer
    -P                          same as --partial --progress

history without line numbers

history | cut -c 8-
  -a	append history lines from this session to the history file  ~/.bash_history

hostname

hostnamectl set-hostname GZ2C8G

font

apt-get install  xfonts-base

SELinux

getenforce
semanage port -a -t mongod_port_t -p tcp 27017

Dropbox

link account

~/.dropbox-dist/dropboxd dropboxd will create a ~/Dropbox folder and start synchronizing it after this step! unlink: https://www.dropbox.com/account#security

Ubuntu snap

run without root

Proxy

vi /etc/environment
systemctl restart snapd

JAVA_HOME

echo export JAVA_HOME="/usr/lib/jvm/java-1.8.0-openjdk" >> /etc/profile

I18N & I10N

apt install -y locales-all
locale -a
dpkg-reconfigure locales

yum grouplist chinese-support

sudo apt-get install -y ttf-wqy-microhei  #文泉驿-微米黑
sudo apt-get install -y ttf-wqy-zenhei  #文泉驿-正黑
sudo apt-get install -y xfonts-wqy #文泉驿-点阵宋体

Chrome

chromium --no-sandbox # start as root

AD

https://wiki.samba.org/index.php/Setting_up_Samba_as_an_NT4_PDC_(Quick_Start)

cache diagnostics

https://hoytech.com/vmtouch/

git clone https://github.com/hoytech/vmtouch.git
cd vmtouch && make && sudo make install

Discovering which files your OS is caching
Telling the OS to cache or evict certain files or regions of files
Locking files into memory so the OS won't evict them
Preserving virtual memory profile when failing over servers
Keeping a "hot-standby" file-server
Plotting filesystem cache usage over time
Maintaining "soft quotas" of cache usage
Speeding up batch/cron jobs

WOL

ethtool enp1s0  | grep Wake-on

p (PHY activity)
u (unicast activity)
m (multicast activity)
b (broadcast activity)
g (magic packet activity) *
a (ARP activity)
d (disabled)

Tools - Online

http://explainshell.com/

CPU

getconf LONG_BIT

check_cpu_core_mapping

https://www.ibm.com/support/knowledgecenter/en/SSQPD3_2.6.0/com.ibm.wllm.doc/mappingcpustocore.html same physical/core ID =》 simultaneous multi threads (SMTs) / HT

cat /proc/cpuinfo  | grep -P 'processor|physical id|core id|^$'

pip install walnut    # pretty print
for c in sorted([ ( int(c['processor']), int(c['physical id']), int(c['core id']) ) for c in cpu.dict().values()]): print c

USB Persistence

https://docs.kali.org/downloading/kali-linux-live-usb-persistence http://antix.mepis.org/index.php?title=Using_liveusb_with_persistence

kali

x86/M1/Live/VM/WSL/etc: https://www.kali.org/get-kali Docker: https://hub.docker.com/u/kalilinux/

ssh

Since 2022.1: https://www.kali.org/docs/general-use/ssh-configuration/

  • kali-tweaks -> Hardening -> Strong Security (the default) and Wide Compatibility

    ls -l /etc/ssh/ssh_host_* systemctl disable regenerate-ssh-host-keys.service

tools

https://www.kali.org/tools/ screenshots/cheat sheet: https://www.comparitech.com/net-admin/kali-linux-cheat-sheet/#Kali_Linux_tools

Video

https://askubuntu.com/questions/28033/how-to-check-the-information-of-current-installed-video-drivers

dpkg -l amdgpu-pro
glxinfo | grep direct
GALLIUM_HUD=help glxgears

OpenCL

installable client driver loader (ICD Loader) may expose multiple separate vendor installable client drivers (Vendor ICDs) for OpenCL.

sudo apt install ocl-icd-opencl-dev

zFCP

device driver that supplements the Linux SCSI stack.

Diagram

diskless

https://help.ubuntu.com/community/DisklessUbuntuHowto

https://drbl.org/

docker run --network=host -d leejoneshane/drbl-server

http://web.mst.edu/~vojtat/pegasus/administration.htm based on Scientific Linux 7 / CentOS 7 / Red Hat Enterprise Linux 7

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