Tag: linux

Linux KVM Bridge network on Ubuntu

On Ubuntu 18.04 server, first i get Ubuntu to use /etc/network/interface, by default Ubuntu 18.04 and newer use netplan.

First install ifdown

apt install ifupdown -y

Install bridge utils and resolvconf.

apt install bridge-utils resolvconf

Now you can configure your network interface by editing file

vi  /etc/network/interface

Here is my network configuration on an OVH server.

root@ns3048991:~# cat /etc/network/interfaces
# interfaces(5) file used by ifup(8) and ifdown(8)
# Include files from /etc/network/interfaces.d:
source-directory /etc/network/interfaces.d

auto eno3
iface eno3 inet static
    address 149.202.199.137
    netmask 255.255.255.255
    broadcast 149.202.199.137
    gateway 149.202.199.254
    dns-nameservers 8.8.8.8 8.8.4.4
root@ns3048991:~#

To convert this interface to bridge network, do the following

1) Replace all occurance of “eno3” with “br0”

2) Add following lines

    bridge_ports eno3
    bridge_stp off
    bridge_maxwait 5

In above, replace “eno3” with name of your physical interface.

Here is my final network configuration.

root@ns3048991:~# cat /etc/network/interfaces
# interfaces(5) file used by ifup(8) and ifdown(8)
# Include files from /etc/network/interfaces.d:
source-directory /etc/network/interfaces.d

auto br0
iface br0 inet static
    address 149.202.199.137
    netmask 255.255.255.255
    broadcast 149.202.199.137
    gateway 149.202.199.254
    bridge_ports eno3
    bridge_stp off
    bridge_maxwait 5
    dns-nameservers 8.8.8.8 8.8.4.4
root@ns3048991:~#

See Linux KVM, Networking @ linux-kvm.org

September 17, 2019

Install Xfce VNC remote desktop on Ubuntu
XFCE is a lightweight Desktop Environment for Linux. XFCE + vnc allows you to set up a remote desktop on a VPS or dedicated server located in a remote data center or cloud. You can connect to remote desktop using a VNC client and work like it is a local computer, similar to Windows Remote Desktop (RDP).

To install XFCE run
```
apt install -y xfce4 xfce4-goodies
```
You will be asked to select Default Display Manager. You can select any of the options.

Next install vncserver
```
apt install tightvncserver autocutsel
```
It is a bad idea to use root user for logging into the desktop. Create a normal user with sudo privileges to be used as desktop user.
```
useradd -m -s /bin/bash USERNAME
```
It will be good to make this user an admin, so the user can install software or update the system.
```
usermod -aG sudo USERNAME
```
Set a password for the user
```
passwd USERNAME
```
Now login as the user
```
su - USERNAME_HERE
```
Create a vnc password for this user.
```
vncpasswd
```
Create vnc startup file
```
vi ~/.vnc/xstartup
```
Add
```
#!/bin/bash

xrdb $HOME/.Xresources
autocutsel -fork
startxfce4 &
```
Make it executable
```
chmod 755 ~/.vnc/xstartup
```
Auto start VNC Server

To autostart vncserver on boot, you need to create a service file. You need to do the following as user root.
```
vi /etc/systemd/system/[email protected]
```
Add
```
[Unit]
Description=Start VNC server at startup
After=syslog.target network.target

[Service]
Type=forking
User=USERNAME
Group=USERNAME
WorkingDirectory=/home/USERNAME

PIDFile=/home/USERNAME/.vnc/%H:%i.pid
ExecStartPre=-/usr/bin/vncserver -kill :%i > /dev/null 2>&1
ExecStart=/usr/bin/vncserver -depth 24 -geometry 1920x1080  :%i
ExecStop=/usr/bin/vncserver -kill :%i

[Install]
WantedBy=multi-user.target
```
In the above, replace USERNAME with the actual user name you created above.

Enable the service with
```
systemctl enable vncserver@1
```
Start the VNC server
```
systemctl start vncserver@1
```
Now reboot the server. You should be able to connect to VNC server using SERVER_IP:1

OPTIONAL: Using RDP instead of VNC

If you want to use RDP (Windows Remote Desktop) to connect instead of VNC, install xrdp
```
apt install -y xrdp
```
Edit
```
vi /etc/xrdp/xrdp.ini
```
Set value of new_cursors to false.
```
new_cursors=false
```
Change to desktop user
```
su - USERNAME
```
Create file
```
vi ~/.xsession
```
Add following content
```
xfce4-session
export XDG_SESSION_DESKTOP=xubuntu
export XDG_DATA_DIRS=/usr/share/xfce4:/usr/local/share:/usr/share:/var/lib/snapd/USERNAME:/usr/share
export XDG_CONFIG_DIRS=/etc/xdg/xfce4:/etc/xdg:/etc/xdg
```
Enable and restart XRDP
```
systemctl enable xrdp
systemctl restart xrdp
```
See VNC Server
September 17, 2019
Install HandBrake on Ubuntu 18.04
HandBreak is an OpenSource Video transcoder available from https://handbrake.fr. It can convert video to various format.

Latest version of Handbreak available in Ubuntu PPA. To install, enable Handbreak PPA
```
add-apt-repository ppa:stebbins/handbrake-releases
```
Install handbreak with
```
apt install handbrake-gtk handbrake-cli
```
September 17, 2019
Install Linux KVM on Ubuntu
Linux KVM is virtualisation software that allow you to create virtual machine under linux. To install on Ubuntu, run
```
apt install -y qemu-kvm qemu-utils
```
Install libvirtd, this allow you to easily create KVM virtual machines and allow remote connection from virt-manager GUI application.

For Ubuntu 20.04
```
apt install -y libvirt-daemon libvirt-daemon-system
```
For Ubuntu 18.04
```
apt install -y libvirt-bin
```
Enable and start libvirt
```
systemctl enable libvirtd
systemctl start libvirtd
systemctl is-active libvirtd
systemctl status libvirtd
```
At this stage, you should be able to connect to KVM server form your computer using virt-manager.

You need to create a bridge network interface (“br0”), for this, follow instructions at Linux KVM Bridge network on Ubuntu.

Downloading ISO

Before you can setup any VM, you need to download ISO image for the OS. Here i downloaded ISO image for Ubuntu 19.04
```
cd /var/lib/libvirt/images
wget http://mirrors.piconets.webwerks.in/ubuntu-mirror/ubuntu-releases/19.04/ubuntu-19.04-live-server-amd64.iso
```
Once downloaded, you should be able to select this ISO image in virt-manager when creating a VM.

See Linux KVM
September 17, 2019
Disable IP Block Alerts in CSF Firewall
To disable IP block alert in CSF firewall, run
```
sed -i "s/LF_PERMBLOCK_ALERT\s*=.*$/LF_PERMBLOCK_ALERT = \"0\"/g" /etc/csf/csf.conf
```
Restart lfd and csf
```
systemctl restart lfd
csf -r
```
See csf firewall
September 17, 2019
Ignore a folder in maldet
maldet is malware scanner for linux. On a shared hosting server, maldet detected one cusomer files as malware, on checking i found it is false positive. It is just a log file written by the application. To avoid getting further email from this application, i added this folder to maldet ignore_paths.

To add a folder to ignore list, edit file
```
vi /usr/local/maldetect/ignore_paths
```
Add the folder you need to ignore to end of this file as a new line.

Example
```
root@server74 [~]# cat /usr/local/maldetect/ignore_paths
/home/welgreenkerala/public_html/login/
/usr/local/maldetect
/usr/local/sbin/maldet
/home/shopatke/public_html/application/logs/
root@server74 [~]# 
```
See maldet
September 16, 2019
Download RPM package from yum repository
To download RPM file from yum repo, you need to install yum-utils package.
```
yum install -y yum-utils
```
Now you can use command
```
yumdownloader --resolve --destdir=/path/ PACKAGE_NAME
```
Example
```
yumdownloader --resolve --destdir=/root/yum/ nginx
```
This will download and store all rpm files in /var/yum folder. –resolve will resolve dependency and download them. This will be helpful if you need to install a package on a system with no direct internet connection.

See yum
September 15, 2019

Enable Passive FTP in ISPConfig

To enable Passive FTP in Debian/Ubuntu installation of ISPConfig, run

echo "40110 40210" > /etc/pure-ftpd/conf/PassivePortRange

Restart pure-ftpd

service pure-ftpd-mysql restart

Now open ports 40110-40210 in firewall.

On CSF Firewall, edit

vi /etc/csf/csf.conf

Add

40110:40210

At ened of TCP_IN line.

Example

TCP_IN = "20,21,22,25,53,80,110,143,443,465,587,993,995,3333,8080,8090,19999,40110:40210"

if you are using AWS, you need to run

echo "YOUR_EXTERNAL_IP_ADDR" > /etc/pure-ftpd/conf/ForcePassiveIP
service pure-ftpd-mysql restart

See ispconfig

September 13, 2019

Install virt-manager on Ubuntu
virt-manager is a GUI tool used to manage KVM virtial machines. To install virt-manager on Ubuntu, run
```
apt install virt-manager
```
September 5, 2019
Clone VM on VMware ESXi using vmkfstools
Free version of VMware ESXi don’t provide option to clone virtual machine. If you want to clone a VM, you need to purchase expensive vSphere license.

There is a work around for this, you need to clone disk of an existing Virtual machine using vmkfstools.

To make clone of a VM disk, SSH into your VMWare ESXi server as user root. Then create clone of disk with
```
vmkfstools -i "source.vmdk" "destination.vmdk"
```
For new VM, i created a directory. Path to datastore directory may be differnt on your server, you can find it using “df -h” command and checking the file system.
```
mkdir /vmfs/volumes/disk2/ubuntu-clone/
```
Shutdown the Virtual Machine you want to clone the disk from. Run
```
[root@ns3048991:~] vmkfstools -i "/vmfs/volumes/disk2/Ubuntu/Ubuntu.vmdk" "/vmfs/volumes/disk2/ubuntu-clone/ubuntu-clone.vmdk"
Destination disk format: VMFS zeroedthick
Cloning disk '/vmfs/volumes/disk2/Ubuntu/Ubuntu.vmdk'...
Clone: 100% done.
[root@ns3048991:~] 
```
In screenshot below, i first tried to clone with out creating destination folder. That resulted in error. After creating destination folder, vmkfstools command worked.

Creating VM using cloned disk

Login to VMware ESXi web interface. Create a new VM. On the step where you select hardware, delete the existing Disk. Add a new disk, browse and select the newly created clone disk. In this case – “/vmfs/volumes/disk2/ubuntu-clone/ubuntu-clone.vmdk”

Once the VM creation is finished, you will be able to start the new VM. You can create a VM, then use it as the template for creating new virtual machines.

See VMWare
September 4, 2019

vmstat

[root@server70 ~]# vmstat -S M 1 10
procs -----------memory---------- ---swap-- -----io---- --system-- -----cpu-----
 r  b   swpd   free   buff  cache   si   so    bi    bo   in   cs us sy id wa st
 0  0     11    770   1009   3119    0    0    28    22   53   51  4  1 94  1  0
 3  0     11    727   1009   3120    0    0    52  2504 8387 2624 12  1 86  1  0
 0  0     11    755   1009   3120    0    0     4   157 4619 1841 12  1 86  1  0
 0  0     11    755   1009   3120    0    0   136     4 9405 1595  2  1 98  0  0
 0  0     11    755   1009   3120    0    0     0    33 4564  875  0  0 99  0  0
 1  0     11    761   1009   3120    0    0    60     0 3151 1157  2  1 97  0  0
 0  0     11    798   1009   3120    0    0    12   984 2937  898  0  0 99  0  0
 0  1     11    828   1009   3120    0    0     0   321 3108 1002  3  0 96  1  0
 0  0     11    813   1009   3120    0    0     4     0 6065 1512  6  1 93  0  0
 1  0     11    848   1009   3120    0    0     4   100 7311 1628  3  1 95  2  0
[root@server70 ~]#

vmstat 1

* High values in “wa” column mean: IO problem
* High values in “si”, “so” mean: excessive swapping

Sustained high swap rates (si and so) are usually bad. The system will start spending all of its time swapping, and make no progress on any actual work. You will also see the number of runnable (r and b) processes increase. If the situation gets bad enough and free memory gets too low, the Out-of-memory (oom) logic will start killing random processes. At this point, either reducing the number of processes that normally run or adding additional RAM are about the only options.

vmstat – Report virtual memory statistics

vmstat [-a] [-n] [delay [ count]]
vmstat [-f] [-s] [-m]
vmstat [-S unit]
vmstat [-d]
vmstat [-p disk partition]
vmstat [-V]

vmstat reports information about processes, memory, paging, block IO, traps, and cpu activity.

The first report produced gives averages since the last reboot. Additional reports give information on a sampling period of length delay. The process and memory reports are instantaneous in either case.

FIELD DESCRIPTION FOR VM MODE


   Procs
       r: The number of processes waiting for run time.
       b: The number of processes in uninterruptible sleep.

   Memory
       swpd: the amount of virtual memory used.
       free: the amount of idle memory.
       buff: the amount of memory used as buffers.
       cache: the amount of memory used as cache.
       inact: the amount of inactive memory. (-a option)
       active: the amount of active memory. (-a option)

   Swap
       si: Amount of memory swapped in from disk (/s).
       so: Amount of memory swapped to disk (/s).

   IO
       bi: Blocks received from a block device (blocks/s).
       bo: Blocks sent to a block device (blocks/s).

   System
       in: The number of interrupts per second, including the clock.
       cs: The number of context switches per second.

   CPU
       These are percentages of total CPU time.
       us: Time spent running non-kernel code. (user time, including nice time)
       sy: Time spent running kernel code. (system time)
       id: Time spent idle. Prior to Linux 2.5.41, this includes IO-wait time.
       wa: Time spent waiting for IO. Prior to Linux 2.5.41, included in idle.
       st: Time stolen from a virtual machine. Prior to Linux 2.6.11, unknown.

FIELD DESCRIPTION FOR DISK MODE

   Reads
       total: Total reads completed successfully
       merged: grouped reads (resulting in one I/O)
       sectors: Sectors read successfully
       ms: milliseconds spent reading

   Writes
       total: Total writes completed successfully
       merged: grouped writes (resulting in one I/O)
       sectors: Sectors written successfully
       ms: milliseconds spent writing

   IO
       cur: I/O in progress
       s: seconds spent for I/O

FIELD DESCRIPTION FOR DISK PARTITION MODE

       reads: Total number of reads issued to this partition
       read sectors: Total read sectors for partition
       writes : Total number of writes issued to this partition
       requested writes: Total number of write requests made for partition

FIELD DESCRIPTION FOR SLAB MODE

       cache: Cache name
       num: Number of currently active objects
       total: Total number of available objects
       size: Size of each object
       pages: Number of pages with at least one active object
       totpages: Total number of allocated pages
       pslab: Number of pages per slab

Related commands

* iostat
* sar
* mpstat
* ps
* top
* free

See Linux Commands

September 4, 2019

vgcreate

To Create a volumegroup.

vgcreate vg1 /dev/sdd1 /dev/sde1

Example

[root@server ~]# vgcreate vg-storage /dev/sdb
  Volume group "vg-storage" successfully created
[root@server ~]# vgdisplay
  --- Volume group ---
  VG Name               vg-storage
  System ID             
  Format                lvm2
  Metadata Areas        1
  Metadata Sequence No  1
  VG Access             read/write
  VG Status             resizable
  MAX LV                0
  Cur LV                0
  Open LV               0
  Max PV                0
  Cur PV                1
  Act PV                1
  VG Size               9.09 TiB
  PE Size               4.00 MiB
  Total PE              2383357
  Alloc PE / Size       0 / 0   
  Free  PE / Size       2383357 / 9.09 TiB
  VG UUID               tAh3cq-EwoJ-6t94-SJtp-YoCC-XCst-4m8Ktp
   
[root@server ~]#

See lvm

September 4, 2019

Tag: linux

Auto start VNC Server

OPTIONAL: Using RDP instead of VNC

Downloading ISO

Creating VM using cloned disk

FIELD DESCRIPTION FOR VM MODE

FIELD DESCRIPTION FOR DISK MODE

FIELD DESCRIPTION FOR DISK PARTITION MODE

FIELD DESCRIPTION FOR SLAB MODE

Related commands