Debian 10.3 Released

Debian Linux

Pretty cool! I almost missed that Debian 10.3 got released last week. This is a corrective release, meaning it’s about improving stability and security rather than about introducing major innovations.

Upgrade Debian 10.2 to 10.3

I only have one dedicated server running Debian 10, and will possibly reinstall even that – turns out I’m much more used to CentOS servers than anything else.

BUT this server is still there, so why not upgrade it?

Step 1: Update Debian repositories

First, we run apt-get update. I never noticed it before, but apparently this command is clever enough to recognize that InRelease changes version from 10.2 to 10.3 (see the last line of the output):

root@srv:~ # apt-get update
 Get:1 http://mirrors.online.net/debian buster InRelease [122 kB]
 Get:2 http://security.debian.org/debian-security buster/updates InRelease [65.4 kB]
 Get:3 https://download.docker.com/linux/ubuntu bionic InRelease [64.4 kB]
 Ign:4 http://mirrors.online.net/debian buster/non-free Sources
 Ign:5 http://mirrors.online.net/debian buster/main Sources
 Ign:6 http://mirrors.online.net/debian buster/main amd64 Packages
 Ign:7 http://mirrors.online.net/debian buster/main Translation-en
 Ign:8 http://mirrors.online.net/debian buster/non-free amd64 Packages
 Ign:9 http://mirrors.online.net/debian buster/non-free Translation-en
 Get:4 http://mirrors.online.net/debian buster/non-free Sources [86.3 kB]
 Get:5 http://mirrors.online.net/debian buster/main Sources [7,832 kB]
 Get:10 http://security.debian.org/debian-security buster/updates/main Sources [102 kB]
 Get:11 http://security.debian.org/debian-security buster/updates/main amd64 Packages [176 kB]
 Get:12 http://security.debian.org/debian-security buster/updates/main Translation-en [92.8 kB]
 Get:6 http://mirrors.online.net/debian buster/main amd64 Packages [7,907 kB]
 Get:7 http://mirrors.online.net/debian buster/main Translation-en [5,970 kB]
 Get:8 http://mirrors.online.net/debian buster/non-free amd64 Packages [88.0 kB]
 Get:9 http://mirrors.online.net/debian buster/non-free Translation-en [88.7 kB]
 Fetched 22.6 MB in 3s (6,828 kB/s)
 Reading package lists… Done
 N: Repository 'http://mirrors.online.net/debian buster InRelease' changed its 'Version' value from '10.2' to '10.3'

Step 2: Upgrade packages and Debian distro

apt-get dist-upgrade brings all the packages to the current release of your Debian/Ubuntu distro. In my case, 

root@srv:~ # apt-get dist-upgrade
 Reading package lists… Done
 Building dependency tree
 Reading state information… Done
 Calculating upgrade… Done
 The following NEW packages will be installed:
   linux-headers-4.19.0-8-amd64 linux-headers-4.19.0-8-common linux-image-4.19.0-8-amd64
 The following packages will be upgraded:
   base-files e2fsprogs git-man libboost-iostreams1.67.0 libboost-system1.67.0 libcom-err2 libcups2 libcupsimage2 libext2fs2 libgnutls30 libidn2-0
   libnss-systemd libopenjp2-7 libpam-systemd libpython3.7 libpython3.7-dev libpython3.7-minimal libpython3.7-stdlib libsasl2-2 libsasl2-modules
   libsasl2-modules-db libss2 libsystemd0 libtiff5 libtimedate-perl libudev1 linux-compiler-gcc-8-x86 linux-headers-amd64 linux-image-amd64 linux-kbuild-4.19
   linux-libc-dev openssh-client openssh-server openssh-sftp-server python-apt python-apt-common python3-apt python3.7 python3.7-dev python3.7-minimal sudo
   systemd systemd-sysv udev
 44 upgraded, 3 newly installed, 0 to remove and 0 not upgraded.
 Need to get 129 MB of archives.
 After this operation, 325 MB of additional disk space will be used.
 Do you want to continue? [Y/n] y
...

Step 3: Reboot (when convenient)

You don’t have to reboot immediately. The biggest reason to do it is to start using new version of Linux kernel, but there’s hardly a specific update in minor kernel upgrade that justifies immediate downtime.

Here’s the kernel version before reboot:

root@srv:~ # uname -a
Linux srv.ts.fm 4.19.0-6-amd64 #1 SMP Debian 4.19.67-2+deb10u2 (2019-11-11) x86_64 GNU/Linux

When possible, you should do a graceful reboot:

root@srv:~ # shutdown -r now

After system is back online, we can see that it’s running Debian Buster 10.3 now:

greys@srv:~ $ uname -a
Linux srv.ts.fm 4.19.0-8-amd64 #1 SMP Debian 4.19.98-1 (2020-01-26) x86_64 GNU/Linux

See Also



Show Files Installed by a Debian/Ubuntu Package

List files in a Debian/Ubuntu package with dpkg-query

Sometimes it’s not enough to know that a certain package is installed on your Linux system. You want to know the full list of files installed by the package, with exact locations of such files. This is when dpkg-query command may help.



Get List of Files Installed by a Package in Ubuntu

I mentioned xz-utils package for XZ archives yesterday, so let’s look at the xz-utils package. This is how I can get the full list of files installed by it:

greys@xps:~ $ dpkg-query -L xz-utils                                                                             [15/15]
 /.                                                                                                                      
 /usr                                                                                                                    
 /usr/bin                                                                                                                
 /usr/bin/lzmainfo                                                                                                       
 /usr/bin/xz                                                                                                             
 /usr/bin/xzdiff                                                                                                         
 /usr/bin/xzgrep                                                                                                         
 /usr/bin/xzless                                                                                                         
 /usr/bin/xzmore                                                                                                         
 /usr/share                                                                                                              
 /usr/share/doc                                                                                                          
 /usr/share/doc/xz-utils                                                                                                 
 /usr/share/doc/xz-utils/README.Debian                                                                                   
 /usr/share/doc/xz-utils/README.gz                                                                                       
 /usr/share/doc/xz-utils/copyright                                                                                       
 /usr/share/doc/xz-utils/extra
 /usr/share/doc/xz-utils/extra/7z2lzma
 /usr/share/doc/xz-utils/extra/7z2lzma/7z2lzma.bash
 /usr/share/doc/xz-utils/extra/scanlzma
 /usr/share/doc/xz-utils/extra/scanlzma/scanlzma.c
 /usr/share/doc/xz-utils/faq.txt.gz
 /usr/share/doc/xz-utils/history.txt.gz
 /usr/share/man
 /usr/share/man/man1
 /usr/share/man/man1/lzmainfo.1.gz
 /usr/share/man/man1/xz.1.gz
 /usr/share/man/man1/xzdiff.1.gz
 /usr/share/man/man1/xzgrep.1.gz
 /usr/share/man/man1/xzless.1.gz
 /usr/share/man/man1/xzmore.1.gz
 /usr/bin/unxz
 /usr/bin/xzcat
 /usr/bin/xzcmp
 /usr/bin/xzegrep
 /usr/bin/xzfgrep
 /usr/share/doc/xz-utils/AUTHORS
 /usr/share/doc/xz-utils/NEWS.gz
 /usr/share/doc/xz-utils/THANKS 
 /usr/share/doc/xz-utils/changelog.Debian.gz
 /usr/share/man/man1/unxz.1.gz
 /usr/share/man/man1/xzcat.1.gz 
 /usr/share/man/man1/xzcmp.1.gz 
 /usr/share/man/man1/xzegrep.1.gz
 /usr/share/man/man1/xzfgrep.1.gz

Find Binaries Installed by a Package

Simple grep will make the previous example even more useful. Let’s say we just want to know if a package installs any binaries, here’s how we can do it:

greys@xps:~ $ dpkg-query -L xz-utils | grep bin
 /usr/bin
 /usr/bin/lzmainfo
 /usr/bin/xz
 /usr/bin/xzdiff
 /usr/bin/xzgrep
 /usr/bin/xzless
 /usr/bin/xzmore
 /usr/bin/unxz
 /usr/bin/xzcat
 /usr/bin/xzcmp
 /usr/bin/xzegrep
 /usr/bin/xzfgrep

That’s it for today. Have fun!

See Also



neofetch in Debian Linux

neofetch on a physical server with Debian Linux

When it comes to reporting basic OS information in one terminal screen for easy screenshot, I’ve been using screenFetch most of the time. Turns out, it’s not the only software of this kind – and neofetch is a great alternative.

neofetch or screenFetch?

Notice how I didn’t say netofetch VS screenFetch!

Because mostly the choice between neofetch and screenFetch is a personal preference: both tools are quite capable and available on majority of popular operating systems.

Reasons to use neofetch

Compared to screenFetch, neofetch has a few really cool features:

  • Server hardware model reported
  • On desktop systems, the following is reported
    • Windows manager and sometimes even desktop theme
    • Screen resolution
  • Better reporting of IP addresses
  • Lots of configuration options

See Also



How To: Setup sudo in Debian

sudo in Debian Linux

Apparently, Debian installer doesn’t install or activate sudo by default. This means that sudo command is not found the only privilege escalation method available is becoming root via su command. Since I like and use sudo daily, I decided to install and setup it on Debian VM.

Install sudo package in Debian

That’s the very first step you’ll need to do: use apt to install sudo. You need to become root before you do it, of course (so you must know root user password for your Debian install):

greys@debian:~$ su -
Password:
root@debian:~ # apt install sudo
Reading package lists… Done
Building dependency tree
Reading state information… Done
The following NEW packages will be installed:
  sudo
0 upgraded, 1 newly installed, 0 to remove and 0 not upgraded.
Need to get 0 B/1,245 kB of archives.
After this operation, 3,886 kB of additional disk space will be used.
Selecting previously unselected package sudo.
(Reading database … 174742 files and directories currently installed.)
Preparing to unpack …/sudo_1.8.27-1_amd64.deb …
Unpacking sudo (1.8.27-1) …
Setting up sudo (1.8.27-1) …
Processing triggers for man-db (2.8.5-2) …
Processing triggers for systemd (241-5) …
root@debian:~ # sudo
usage: sudo -h | -K | -k | -V
usage: sudo -v [-AknS] [-g group] [-h host] [-p prompt] [-u user]
usage: sudo -l [-AknS] [-g group] [-h host] [-p prompt] [-U user] [-u user] [command]
usage: sudo [-AbEHknPS] [-r role] [-t type] [-C num] [-g group] [-h host] [-p prompt] [-T timeout] [-u user] [VAR=value] [-i|-s] []
usage: sudo -e [-AknS] [-r role] [-t type] [-C num] [-g group] [-h host] [-p prompt] [-T timeout] [-u user] file …

Configure /etc/sudoers File

/etc/sudoers is the main configuration file for sudo command. It contains list of users and groups that are allowed to become root (or become other users by invoking su command as root).

Here’s the default file in Debian 10 Buster:

root@debian:~ # cat /etc/sudoers
#
# This file MUST be edited with the 'visudo' command as root.
#
# Please consider adding local content in /etc/sudoers.d/ instead of
# directly modifying this file.
#
# See the man page for details on how to write a sudoers file.
#
Defaults        env_reset
Defaults        mail_badpass
Defaults        secure_path="/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin"
# Host alias specification
 
# User alias specification
 
# Cmnd alias specification
 
# User privilege specification
root    ALL=(ALL:ALL) ALL
 
# Allow members of group sudo to execute any command
%sudo   ALL=(ALL:ALL) ALL
 
# See sudoers(5) for more information on "#include" directives:
#includedir /etc/sudoers.d

I’ve highlighted the 3 most important elements of this file at this early stage:

root    ALL=(ALL:ALL) ALL

This is the line that allows you to debug sudo commands as root user.

At this means that any user that belongs to group sudo will also be allowed to use sudo commands:

%sudo   ALL=(ALL:ALL) ALL

Finally, this part includes additional configuration files from /etc/sudoers.d directory:

#includedir /etc/sudoers.d

… this means you don’t have to edit /etc/sudoers file but instead can create a specific file in /etc/sudoers.d and name it self-descriptively, like:

/etc/sudoers.d/web-server-admins

meaning, that this file will contain usernames and privileges required by web-server admins (usually commands like stopping/starting Apache or nginx webserver).

Since this is a very basic tutorial, we don’t have to edit the file at all – just need to add our user (mine is greys, as you remember) to the sudo group and check.

Add user to sudo group

Step 1: let’s make sure sudo is not accessible before we begin

This needs to be run as your regular user, not as root:

greys@debian:~$ sudo -i
[sudo] password for greys:
greys is not in the sudoers file.  This incident will be reported.
greys@debian:~$

Let’s check my groups just to be sure there’s no sudo among them:

greys@debian:~$ id greys
uid=1000(greys) gid=1000(greys) groups=1000(greys),24(cdrom),25(floppy),29(audio),30(dip),44(video),46(plugdev),108(netdev),112(bluetooth),116(scanner)

Step 2: add user to sudo group

Excellent, now it’s time to add user greys to the group sudo (we must become root again to run usermod command)

root@debian:~ # usermod -a -G sudo greys
root@debian:~ # id greys
uid=1000(greys) gid=1000(greys) groups=1000(greys),24(cdrom),25(floppy),27(sudo),29(audio),30(dip),44(video),46(plugdev),108(netdev),112(bluetooth),116(scanner)

As you can see, I’m now a member of the sudo group!

Step 3: Log out and log back in for group membership to be recognised

Now you need to disconnect from your server or desktop session and log in again, so that your group membersip is recognised. One reconnected, check your groups with id command and try sudo again:

greys@debian9:~$ id
uid=1000(greys) gid=1000(greys) groups=1000(greys),24(cdrom),25(floppy),27(sudo),29(audio),30(dip),44(video),46(plugdev),108(netdev),112(bluetooth),116(scanner)

so yes, we’re a member of sudo group now… This is the moment of truth! Let’s try to become root:

greys@debian:~$ sudo -i
root@debian:~ # id
uid=0(root) gid=0(root) groups=0(root)

Tha’ts it for today!

See Also



ifconfig command not found

ifconfig command not found
ifconfig command not found

Call me old fashioned, but I still prefer using ifconfig command. It’s not as cool as the ip command found in recent Linux distros, but familiar and universal enough to be found pretty much everywhere else. This post shows how to install packages to make ifconfig working again.

/sbin/ifconfig: no such file or directory

Yep, that’s the error message I’m seeing on most recent distros. This simply means that ifconfig is no longer a core functionality installed with a base OS. You can still get it by installing net-tools package in your environment.

Here’s how my attempt looked on Debian 9 (Stretch) VM just a few minutes ago:

greys@debian9:~$ ifconfig -a
-su: /sbin/ifconfig: No such file or directory

Install net-tools package for ifconfig and more

Simple enough step (I just know and remember that ifconfig is in net-tools package):

You need to have superuser powers, and by default Debian 9 doesn’t have sudo installed – so I’m just using su command to become root:

greys@debian9:~$ su -
Password:

And now we install the net-tools package:

root@debian9:~# apt install net-tools
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following NEW packages will be installed:
net-tools
0 upgraded, 1 newly installed, 0 to remove and 154 not upgraded.
Need to get 248 kB of archives.
After this operation, 963 kB of additional disk space will be used.
Get:1 http://ftp.ie.debian.org/debian stretch/main amd64 net-tools amd64 1.60+git20161116.90da8a0-1 [248 kB]
Fetched 248 kB in 0s (601 kB/s)
Selecting previously unselected package net-tools.
(Reading database ... 128276 files and directories currently installed.)
Preparing to unpack .../net-tools_1.60+git20161116.90da8a0-1_amd64.deb ...
Unpacking net-tools (1.60+git20161116.90da8a0-1) ...
Processing triggers for man-db (2.7.6.1-2) ...
Setting up net-tools (1.60+git20161116.90da8a0-1) ...

That’s it, ifconfig should start working right away:

root@debian9:~# ifconfig -a
enp0s3: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 192.168.X.Y netmask 255.255.255.0 broadcast 192.168.1.255
inet6 fe80::a00:27ff:febe:8a41 prefixlen 64 scopeid 0x20<link>
ether 08:00:27:be:8a:41 txqueuelen 1000 (Ethernet)
RX packets 94337 bytes 138887593 (132.4 MiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 31380 bytes 2338487 (2.2 MiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0

lo: flags=73<UP,LOOPBACK,RUNNING> mtu 65536
inet 127.0.0.1 netmask 255.0.0.0
inet6 ::1 prefixlen 128 scopeid 0x10<host>
loop txqueuelen 1 (Local Loopback)
RX packets 1154 bytes 292002 (285.1 KiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 1154 bytes 292002 (285.1 KiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0

See Also