Remove Apache Tomcat on Debian to use Jetty sever

I’m a beginner on linux, and I would like to install a wiki software on a server, a virtual machine with debian 10.

First I began to follow the tutorial 1 to install Bluespice 3, a wiki sofware, the Apach part is ok, then Jetty. Afterthat I installed Apache Tomcat 9 with the help of another tutorial, tutorial 2. Then I realized jetty has the same functionnallity (Tomcat 9) and prefered by tutorial 1.

To get to the point, I want to delete Apache Tomcat to prioritize jetty, and to keep following the tutorial 1. But I didn’t install Tomcat 9 via the command line "apt-get install….", but via the extraction of tar.gz file, with the creation of Tomcat group… so i do not know the exact package names of tomcat 9 to remove its properly. Is there a specific package property of tomcat 9 to remove its properly?

Otherwise, maybe an other solution. When I type in the web browser http://localhost:8080, the web page is 404 error with the message: "the origin of the server did not find a current representation for the target ressource or is not willing to disclose that one exits". In the left bottom, it’s written "Apache Tomcat/9.0.37. I think Tomcat has the priority. But in this case I would like the html page of Bluespice3, knowing the Bluespice war file is at the right location in /var/lib/jetty9/webapps Can I modify the path between localhost and server to give the priority at jetty, without removing tomcat? Is it possible?

Thanks in advance for your help*

Why is disk IO higher on Debian 10 (MariaDB 10.3) with MySQL replication?

I have a MySQL/MariaDB master-master replication setup that has been working well for several years, the db and tables are not very large (under 200MB for 18 tables). These were on 2 servers running Debian 9 and MariaDB 10.1.44. Now I’ve spun up 2 new servers running Debian 10 and I’m in the process of moving things over to them, but stopped half-way because I’m seeing much higher disk IO usage on the new servers (about 6x more).

So currently, one of the Debian 9 servers and one of the Debian 10 servers are in master-master relationship, with one Debian 9 still being a slave of the master Debian 9 server, and same on the Debian 10 side of things.

I didn’t notice the increased disk IO until after all read/write operations were moved to the Debian 10 master. I was trying to browse tables and saw how slow it was outputting the query results, and it felt like I was on a dial-up connection watching the rows scroll across. It turned out there was some disk contention with the virtual host that was partly responsible, and that problem is now mostly gone.

Now, as you can imagine, none of this is crashing the server with such a "small" set of tables, but as things continue to grow, I’m concerned that there is some underlying mis-configuration which will rear its ugly head at an inopportune time. On the Debian 9 servers, iotop shows steady write IO at around 300-600Kb/s, but on Debian 10 it spikes as high as 6MB/s, and averages around 3MB/s.

Here is the standard config on all 4 servers, everything else is default Debian settings (or MariaDB, as the case may be), full config for Debian 10 at https://pastebin.com/Lk2FR4e3:

max_connections = 1000 query_cache_limit       = 4M query_cache_size        = 0 query_cache_type        = 0 server-id               = 1 # different for each server log_bin                 = /var/log/mysql/mysql-bin.log binlog_do_db            = optimizer replicate-do-db         = optimizer report-host             = xyz.example.com #changed obviously log-slave-updates       = true innodb_log_file_size    = 32M innodb_buffer_pool_size = 256M 

Here are some other settings I’ve tried that don’t seem to make any difference (checked each one by one):

binlog_annotate_row_events = OFF binlog_checksum = NONE binlog_format = STATEMENT innodb_flush_method = O_DIRECT_NO_FSYNC innodb_log_checksums = OFF log_slow_slave_statements = OFF replicate_annotate_row_events = OFF 

I’ve gone through all the settings here that have changed from MariaDB 10.1 to 10.3, and can’t seem to find any that make a difference: https://mariadb.com/kb/en/replication-and-binary-log-system-variables/

I also did a full listing of the server variables and compared the configs on 10.1 to the 10.3 configuration and didn’t find anything obvious. But either I’m missing something, or the problem lies with Debian 10 itself.

Results of SHOW ENGINE INNODB STATUS are here: https://pastebin.com/mJdLQv8k

Now, how about that disk IO, what is it actually doing? I include 3 screenshots here to show what I mean by increased disk IO: Resource graphs on the Debian 10 master

That is from the Debian 10 master, and you can see where I moved operations back to the Debian 9 server (more on that in a second). Notice the disk IO does go down slightly at that point, but not to the levels that we’ll see on the Debian 9 master. Also note that the public bandwidth chart is pretty much only replication traffic, and that the disk IO far outstrips the replication traffic. The private traffic is all the reads/writes from our application servers.

Resource graphs on Debian 9 master

This is the Debian 9 master server, and you can see where I moved all operations back to this server, the private traffic shoots up, but the write IO hovers around 500kB/s. I didn’t have resource graphs being recorded on the old servers, thus the missing bits on the left.

Debian 10 slave server resource graphs

And lastly, for reference, here is the Debian 10 slave server (that will eventually be half of the master<–>master replication). There are no direct reads/writes on this server, all disk IO is from replication.

Just to see what would happen (as I alluded to above), I reverted all direct read/write operations to the Debian 9 master server. While disk IO did fall somewhat on the Debian 10 server, it did not grow on the Debian 9 server to any noticeable extent.

Also, on the Debian 10 slave server, I did STOP SLAVE once to see what happened, and the disk IO went to almost nothing. Doing the same on the Debian 10 master server barely did not have the same drastic effect, though it’s possible there WAS some change that wasn’t obvious; the disk IO numbers on iostat fluctuate much more wildly on the Debian 10 servers than they do on the Debian 9 servers.

So, what is going on here? How can I figure out why MariaDB is writing so much data to disk apparently and/or how can I stop it?

Thanks in advance!

Netcat on Debian Security advice please nc -(dknl) [closed]

This is with regards to a Netcat based script running on a Debian based distribution, specifically the Proxmox hypervisor (see here if unknown https://en.wikipedia.org/wiki/Proxmox_Virtual_Environment)

I would need to run a script to start a Virtual Machine from a remote PC within the network. The script running on this Proxmox (Debian) distribution is as follows:

**nc -dknl -p 9 -u |**  stdbuf -o0 xxd -c 6 -p | stdbuf -o0 uniq | stdbuf -o0 grep -v 'ffffffffffff' | while read ; do MAC=$  {REPLY:0:2}:$  {REPLY:2:2}:$  {REPLY:4:2}:$  {REPLY:6:2}:$  {REPLY:8:2}:$  {REPLY:10:2}; echo Received Address: $  MAC if [ "$  MAC" == "0c:d2:92:48:68:9b" ] then echo STARTING VM! qm start 101   # Proxmox Command to start Virtual machine. fi done 

Could the Debian running above script be exploited, as Netcat listens on Port 9 UDP (it could of course listen to another port as well if I change that)? Naturally, anyone in the network could start a VM, but is there another risk?

Debian GUI programming question

I do not know how to correctly formulate the question. I have utilities on the bash, with communication with the user through zenity. It became a little crowded, and in general, I want the IDE, states, databases, tray icons

I look closely at PyQt. It seems like Qt will facilitate the creation of an interface and Python is a progressive language. Complexities and subtleties are not necessary, but ready-made ones would be welcome.

Or am I looking the wrong way?

Why is Debian not showing the GPG signatures on keys that Arch Linux is?

I downloaded a Qubes OS ISO and I’m trying to verify its legitimacy using this guide. GPG was behaving weirdly, so I created a separate user with a separate keyring to reproduce the issue.

When I try to verify the key on my Debian system, the signature on the release signing key is not there:

$   gpg --fetch-keys https://keys.qubes-os.org/keys/qubes-master-signing-key.asc gpg: directory '/home/test/.gnupg' created gpg: keybox '/home/test/.gnupg/pubring.kbx' created gpg: requesting key from 'https://keys.qubes-os.org/keys/qubes-master-signing-key.asc' gpg: /home/test/.gnupg/trustdb.gpg: trustdb created gpg: key DDFA1A3E36879494: public key "Qubes Master Signing Key" imported gpg: Total number processed: 1 gpg:               imported: 1 $   gpg --fetch-keys https://keys.qubes-os.org/keys/qubes-release-4-signing-key.asc gpg: requesting key from 'https://keys.qubes-os.org/keys/qubes-release-4-signing-key.asc' gpg: key 1848792F9E2795E9: public key "Qubes OS Release 4 Signing Key" imported gpg: Total number processed: 1 gpg:               imported: 1 $   gpg --list-sigs "Qubes OS" pub   rsa4096 2017-03-06 [SC]       5817A43B283DE5A9181A522E1848792F9E2795E9 uid           [ unknown] Qubes OS Release 4 Signing Key sig 3        1848792F9E2795E9 2017-03-06  Qubes OS Release 4 Signing Key $   

I expected another line with a signature from the master key, such as

sig          DDFA1A3E36879494 2017-03-08  Qubes Master Signing Key 

Surprised, I decided to check on another system. This one is running Arch Linux. I trust it less than the Debian system. Perplexingly, the signature does show up — the output is just as above, but with the added signature line.

The GPG version is 2.2.17 on both machines.

What could be causing this discrepancy?

DEBIAN 10 UPDATING ISSUES

I have just done a clean installation of debian buster, and I’m having trouble with apt update (I’m posting this question to this community since ubuntu it’s just a distribution of debian, so i guessed somebody could help).

UPDATES PROBLEM

I run sudo apt update and I get this

    Ign:1 cdrom://[Debian GNU/Linux 10.1.0 _Buster_ - Official amd64 NETINST 20190908-01:07] buster InRelease Err:2 cdrom://[Debian GNU/Linux 10.1.0 _Buster_ - Official amd64 NETINST 20190908-01:07] buster Release   Please use apt-cdrom to make this CD-ROM recognized by APT. apt-get update cannot be used to add new CD-ROMs Hit:3 http://deb.debian.org/debian buster InRelease               Ign:4 http://deb.debian.org/debian buster/updates InRelease       Hit:5 http://deb.debian.org/debian buster-updates InRelease Err:6 http://deb.debian.org/debian buster/updates Release   404  Not Found [IP: 151.101.132.204 80] Reading package lists... Done E: The repository 'cdrom://[Debian GNU/Linux 10.1.0 _Buster_ - Official amd64 NETINST 20190908-01:07] buster Release' does not have a Release file. N: Updating from such a repository can't be done securely, and is therefore disabled by default. N: See apt-secure(8) manpage for repository creation and user configuration details. E: The repository 'http://deb.debian.org/debian buster/updates Release' does not have a Release file. N: Updating from such a repository can't be done securely, and is therefore disabled by default. N: See apt-secure(8) manpage for repository creation and user configuration details. W: Target Packages (main/binary-amd64/Packages) is configured multiple times in /etc/apt/sources.list:3 and /etc/apt/sources.list:4 W: Target Packages (main/binary-all/Packages) is configured multiple times in /etc/apt/sources.list:3 and /etc/apt/sources.list:4 W: Target Translations (main/i18n/Translation-en_US) is configured multiple times in /etc/apt/sources.list:3 and /etc/apt/sources.list:4 W: Target Translations (main/i18n/Translation-en) is configured multiple times in /etc/apt/sources.list:3 and /etc/apt/sources.list:4 W: Target DEP-11 (main/dep11/Components-amd64.yml) is configured multiple times in /etc/apt/sources.list:3 and /etc/apt/sources.list:4 W: Target DEP-11 (main/dep11/Components-all.yml) is configured multiple times in /etc/apt/sources.list:3 and /etc/apt/sources.list:4 W: Target DEP-11-icons-small (main/dep11/icons-48x48.tar) is configured multiple times in /etc/apt/sources.list:3 and /etc/apt/sources.list:4 W: Target DEP-11-icons (main/dep11/icons-64x64.tar) is configured multiple times in /etc/apt/sources.list:3 and /etc/apt/sources.list:4 

Here you have the content of my sources.list

    #   deb cdrom:[Debian GNU/Linux 10.1.0 _Buster_ - Official amd64 NETINST 20190908-01:07]/ buster main deb cdrom:[Debian GNU/Linux 10.1.0 _Buster_ - Official amd64 NETINST 20190908-01:07]/ buster main  deb http://deb.debian.org/debian/ buster main deb-src http://deb.debian.org/debian/ buster main  deb http://deb.debian.org/debian/ buster/updates main deb-src http://deb.debian.org/debian/ buster/updates main  # buster-updates, previously known as 'volatile' deb http://deb.debian.org/debian/ buster-updates main deb-src http://deb.debian.org/debian/ buster-updates main  # This system was installed using small removable media # (e.g. netinst, live or single CD). The matching "deb cdrom" # entries were disabled at the end of the installation process. # For information about how to configure apt package sources, # see the sources.list(5) manual. 

I really can’t understand what’s the problem here, if these are the default sources that came with my clean installation inside the file, I changed nothing.

Can I create an uninstallable debian package which overwrite’s another package’s files?

I’m trying to create a Debian package which installs a custom keyboard layout. In order to do this, you need to modify two files in /usr/share/X11/xkb. So my package just includes the new versions of those files. When I try to install it, dpkg complains about conflicts with the xkeyboard package and won’t let me. I’m aware that I could use --force-overwrite to install it anyway, but I’m worried about uninstalling the package later. I’d like to create a Debian package with the following behavior:

  1. When installed, overwrites files belonging to another package.
  2. When uninstalled, files return to the state they were in before the installation.

Is this possible?

I want to install Ubuntu on my Google Coral. It comes with a custom derivative of Debian

I want to install Ubuntu on my Google Coral. It comes with a custom derivative of Debian. The OS that ships with it is pretty limited. I can’t do anything and a lot of things are missing. It would probably be easier to run the additional software they bundle with it on Ubuntu or maybe Ubuntu can use the TPU like an accelerator dongle.