Linux Workspace Shortcuts

Ctrl+Alt and tap an arrow key to quickly move up, down, left, or right between workspaces
Shift+Ctrl+Alt and tap an arrow key to switch between workspaces.

Docker Containers Have No Access Internert

Problem
Docker containers cannot access the network. The host can normal and containers have no problem to access the host.

LVM Extend ROOT with EXT4 File System

Problem: root partition was full.

$ df -h
Filesystem                         Size  Used Avail Use% Mounted on
udev                               3.9G     0  3.9G   0% /dev
tmpfs                              799M   67M  732M   9% /run
/dev/mapper/silver--vg-root         37G   36G     0 100% /
...

SSH Certificate Authentication

Generate ssh certificate

ssh-keygen -t rsa -b 4096 -C "your_email@example.com"

LXD 3.0 Container with Container Commands

Use init instead of launch to create new container.
```
lxc init ubuntu:18.04 c1
```

Chromebook Secure Shell App Remove Known_hosts

Using CTRL+SHIFT+J to open Javascript console. Run the following command to clear all knownhosts.

term_.command.removeAllKnownHosts()

KVM Qemu Forward Ports with iptables

Forward rule:

sudo iptables -I FORWARD -o virbr0 -d 192.168.122.0/24 -j ACCEPT

Centos KVM Guest No Internet Access

It is strange that guest cannot access internet.
Try step 1:

sudo systemctl restart libvirtd

Mount USB Drive Automatically on Ubuntu

Find USB UUID

sudo blkid /dev/sdb2 | awk -F'"' '{print $2}'

Postfix Monitor Sent Mails and Block Domains

Check how many mails has been sent via postfix.

If the number is to big, it must be hacked by someone on some services.

sudo grep "status=sent" /var/log/mail.log | egrep -ve 'postfix/(cleanup|pickup|master|qmgr|smtpd|local|pipe)' | wc -l