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computing:miscadmin

  • miscadmin
  • Jonathan Haack
  • Haack's Networking
  • netcmnd@jonathanhaack.com

A dumping ground for basic gnulinux sysadmin and other miscellaneous notes, or miscadmin for short.


-Text Editors-

Change the default text editor, terminal, web browser, in Debian

exo-preferred-applications

Some systems are not kind with exo, so …

xdg-mime default caja.desktop inode/directory application/x-gnome-saved-search

Set caja or other file managers to manage desktop

gsettings set org.gnome.desktop.background show-desktop-icons false
gsettings set org.nemo.desktop show-desktop-icons true

-motd-

Create the following to make a message of the day that will be appended to the dynamic message of the day.

sudo nano /etc/motd

Is motd printing twice, comment out motd statis in pam setting

/etc/pam.d/sshd
#session    optional     pam_motd.so noupdate
(actually it is the line above this, leave this active)

Print motd with every shell log in …

nano ~/.bashrc

Navigate to the end of the file, and add

cat /etc/motd

-Firefox-

To install the latest firefox on Debian and make it default, do the following. The link below may not always work, so replace when updated.

sudo mkdir -p /opt/firefox
sudo chown -R $USER:$USER /opt/firefox
cd ~/Downloads && wget -O FirefoxSetup.tar.bz2 "https://download.mozilla.org/?product=firefox-latest&os=linux64&lang=en-US"
tar xjf FirefoxSetup.tar.bz2 -C /opt/firefox/
sudo mv /usr/lib/firefox-esr/firefox-esr /usr/lib/firefox-esr/firefox-esr_orig
sudo ln -s /opt/firefox/firefox/firefox /usr/lib/firefox-esr/firefox-esr

To restore firefox-esr that comes with Debian.

unlink /usr/lib/firefox-esr/firefox-esr
mv /usr/lib/firefox-esr/firefox-esr_orig /usr/lib/firefox-esr/firefox-esr

-youtube-dl-

sudo curl -L https://yt-dl.org/downloads/latest/youtube-dl -o /usr/local/bin/youtube-dl
sudo chmod 750 /usr/local/bin/youtube-dl

-optical ripping example-

cdrecord -pad -dao -data blag-140k-i686.iso

-pam hardening location-

sudo nano /etc/pam.d/common-password

Prevent Log in - create file

/etc/nologin

-old reminders-

remove old and offending keyring from gnome, make new directory for new one

sudo rm -rf ~/.local/share/keyrings
mkdir ~/.local/share/keyrings

start or stop network manager (or other services)

systemctl <start/stop/restart> networkmanager.service
/etc/init.d/network-manager <start/stop/restart>

verify dhcp client working for interface eno1

dhclient -v eno1

add subnet to interface eno1

ip address add 192.1##.1##.2/24 dev eno1

interface tool w/ eno1 example

ethtool eno1  

interface with switch using screen

screen /dev/ttyUSB0/ 19200

calculate subnet automatically

subnetcalc

proxying web traffic through remote server

ssh -D <port#> <user>@<domain.com>

get block ID of drives

blkid

nmap to scan devices on lan

nmap -sP 10.##.##.0/24

find utils example

find . -iname "name" 

-ngrok-

ngrok notes; private http(s) tunnels

./ngrok http 80
wget https://[ngrok tunnel]/id_rsa.pub
cat ~/id_rsa.pub >> ~/.ssh/authorized_keys

query hosts on the lan

avahi-browse -tl _workstation._tcp

Debian print system configuration to stdout; use root

cat /proc/cpuinfo && lspci | grep -i vga && uname -a && lsb_release -a
lsb_release -a
lspci

Debian repo management

cd /etc/apt
nano sources.lsit
[main contrib non-free]

-sftp basics-

cd ~/Downloads
sftp user@host.com:/path/to/sftp/directory/of/choice/
> put /path/to/file.txt 

-build app from source-

tar -xf <source_filename>

Navigate to the directory that tar unarchived the files to. Then, within that directory, execute:

./configure --prefix=/usr/local

make
sudo make install clean

-using vi to scrape unnecessary text strings away from openwrt packages that need updating

:1,$s/ .*//

-passing traffic through wifi radio to another interface on host-

sudo su -c "iptables -t nat -A POSTROUTING -o wlp2s0 -j MASQUERADE"
sudo su -c "echo 1 > /proc/sys/net/ipv4/ip_forward"
set a static ip using ip a a x.x.x.x. dev blah
set static on wndr wan

-exim delete all messages and other-

exim -bp <print message ids>
exim -Mrm <message id>
exim -bp | awk '/^ *[0-9]+[mhd]/{print "exim -Mrm " $3}' | bash

use this for local interfaces for ipv6
::::0:0.0.0.0

-verifying TLS with swaks on exim4 relay setup

swaks -a -tls -q HELO -s smtp.haacksnetworking.com:587 -au test -ap '<>'

-mysql password-

nano /etc/mysql/debian.cnf 
sudo mysql -u debian-sys-maint  

-temporary name servers - how to add some - temporary/permanent syntax below:

echo "nameserver 4.2.2.1" | sudo tee /etc/resolv.conf > /dev/null
echo "nameserver 4.2.2.1" | sudo tee /etc/resolvconf/resolv.conf.d/base > /dev/null

-strip desktop environments from GUI system

tasksel --list-tasks
tasksel --task-packages desktop
sudo apt-get purge $(tasksel --task-packages desktop)

-deborphan

sudo apt install deborphan
sudo apt-get remove `deborphan`
for i in `deborphan`; do apt-get --purge remove -y $i; done

-checking ssh logs

cat /var/log/auth.log | grep 'sshd.*Invalid'
cat /var/log/auth.log | grep 'sshd.*opened'

oemb1905 2019/11/02 20:56

computing/miscadmin.txt · Last modified: 2020/01/05 11:53 by oemb1905