Ubuntu is an open source software operating system that runs from the desktop, to the cloud, to all your internet connected things.

Share tech news, updates, or what's on your mind.

Sign up to Post

I've got Ubuntu 16.04 and OpenVPN installed and seems to be working fine. But when I check firewall rules using "sudo ufw status", then I see this:
Status: active

To                         Action      From
--                         ------      ----
80                         ALLOW       Anywhere                  
443                        ALLOW       Anywhere                  
53                         ALLOW       Anywhere                  
465                        ALLOW       Anywhere                  
25                         ALLOW       Anywhere                  
110                        ALLOW       Anywhere                  
995                        ALLOW       Anywhere                  
143                        ALLOW       Anywhere                  
993                        ALLOW       Anywhere                  
10025                      ALLOW       Anywhere                  
10024                      ALLOW       Anywhere                  
80 (v6)                    ALLOW       Anywhere (v6)             
443 (v6)                   ALLOW       Anywhere (v6)             
53 (v6)                    ALLOW       Anywhere (v6)             
465 (v6)                   ALLOW       Anywhere (v6)             
25 (v6)                    ALLOW       Anywhere (v6)             
110 (v6)                   ALLOW       Anywhere (v6)             
995 (v6)                   ALLOW       Anywhere (v6)             
143 (v6)                   ALLOW       

Open in new window

Learn SQL Server Core 2016
LVL 13
Learn SQL Server Core 2016

This course will introduce you to SQL Server Core 2016, as well as teach you about SSMS, data tools, installation, server configuration, using Management Studio, and writing and executing queries.

i have an iso of 18.04.3 desktop-amd64.iso.  how do i burn this to a dvd?  i've done it before but i forget.  i'm currently running ubuntu 16.04.
I have Ubuntu 16.04 (Desktop Edition) with OpenVPN server and BIND9 installed. I used a script when I installed OpenVPN. My OpenVPN client is a W10 netbook with 4G USB modem.
When I choose to use Google DNS during OpenVPN installation then I can surf the Internet via OpenVPN just fine (on my OpenVPN client W10 machine). But if I choose to use a current DNS settings (ie. my own BIND9 server), then I can connect from client to server, but DNS doesn't work. I know that I must edit config file of OpenVPN server server.conf AND to also edit client.ovpn client's OpenVPN file too. And I don't know exactly whether my DNS server (BIND9) is properly configured to play this kind of role.
When I go to W10's CMD and do ipconfig /all I do see DNS server with a correct IP of my BIND9 (it's a public IP of my Ubuntu machine, actually). Nevertheless, DNS doesn't work on a client machine and I couldn't find a complete step-by-step manual how to enable this scheme.

Having a somewhat surprising issue - our mail flow on our Zimbra server is down (both inbound and outbound) yet the server seems healthy and no error seems reported.

1. Server is up (8.8.10_GA_3786) on Ubuntu 16
2. Admin health status page shows every service up & running (green)
3. Webmail access is ok
4. IMAP access is ok

However, no mail is flowing in or out.

Trying to send triggers the following errors:


19:03:25 Ready to run action (retry count: 0)
19:03:25 Clearing connection to zimbrams.domain.com
19:03:25 Trying to connect to zimbrams.domain.com on port 465 (CFNetwork) with STARTTLS (required)
19:03:25 Resolved hostname (zimbrams.domain.com).
19:03:25 Error: Connection error (Connection refused).
19:03:25 Error code: 2
19:03:25 Failed action (0). Reset observed read/write timeouts: 8/8

Open in new window

MBP13:~ alex$ telnet zimbra.domain.com 25
Trying *.*.187.68...
telnet: connect to address *.*.187.68: Connection refused
telnet: Unable to connect to remote host
MBP13:~ alex$ 

Open in new window

(ie the connexion is actively refused)


method:	[unknown]
msg:	try again: Unable to connect to the MTA
code:	mail.TRY_AGAIN
detail:	soap:Receiver
trace:	qtp66233253-2518:1568314842997:7a36c58c222c3898
Body: {
  SendMsgRequest: {
    _jsns: "urn:zimbraMail",
    m: {
      e: [
        // [0]:
          a: "someone@gmail.com",
          t: "t"
        // [1]:

Open in new window

I have a digital scale connected via USB to my Ubuntu laptop and I would like to read the measurements from it.
The serial protocol is very simple (9600,8N1, ttyUSB0) and I'm able to correctly read the measurements by using putty (VT100+) from terminal.

The scale needs to receive the command

Open in new window

in order to send the measurement.
Each measurement has this format:
01ST,GS,   2.5,kg<CR><LF>

Open in new window

if, for example, I'm measuring a 2.5Kg load.

Now, I'm trying to send the READ command from a C application, but I'm not able to get any answer.

#include <errno.h>
#include <fcntl.h> 
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <termios.h>
#include <unistd.h>

int set_interface_attribs(int fd, int speed)
    struct termios tty;

    if (tcgetattr(fd, &tty) < 0) {
        printf("Error from tcgetattr: %s\n", strerror(errno));
        return -1;

    cfsetospeed(&tty, (speed_t)speed);
    cfsetispeed(&tty, (speed_t)speed);

    tty.c_cflag |= (CLOCAL | CREAD);    /* ignore modem controls */
    tty.c_cflag &= ~CSIZE;
    tty.c_cflag |= CS8;         /* 8-bit characters */
    tty.c_cflag &= ~PARENB;     /* no parity bit */
    tty.c_cflag &= ~CSTOPB;     /* only need 1 stop bit */
    tty.c_cflag &= ~CRTSCTS;    /* no hardware flowcontrol */

    /* setup for non-canonical mode */
    tty.c_iflag &= ~(IGNBRK | BRKINT | PARMRK | ISTRIP | INLCR | IGNCR | ICRNL | IXON);
    tty.c_lflag &= ~(ECHO | ECHONL | ICANON |

Open in new window

I have an electronics board which has 16 relays and it works over TCP/IP.
The IP address of the board is and the port is 3000.
I would like to control it with C/C++ under Ubuntu.

There is a list of HEX commands that it is possible to use in order to remotely switch ON and OFF each relay on the board.
This is the list:
"580112000000016C",  // switch on the relay 1

"580111000000016B",  // switch off the relay 1
"580112000000026D", // switch on the relay 2
"580111000000026C", // switch off the relay 2
"580112000000036E", // so on..

I'm correctly able to switch on and off each relay by sending command line commands under Ubuntu:

echo '580112000000016C' | xxd -r -p | nc 3000

Open in new window

The above code correctly turns on the relay.

I would like to do the same with C/C++ code since I want to control the …
Hello expert,
We are not able to run any command in our Ubuntu 18 LTS and we are getting the following error "cannot create temp file for here-document: No space left on device". So, how can I free up space if the root account is itself looked.
i have a nas which is mounted in ubuntu 16.
nas is restarted and ubuntu missing this mount.
Now i can't mount it because the old one is running i can't find the process via ps -ef | grep nfs
and i do not like to reboot server because of that.how to find process it's no possible to make ls -l /mnt/archive because it old one running
i can without any problem mount it under fx. /test but i need to stop the old one.
I've written some simple Python scripts and now I would like to write a Python script that can be installed and run as a service.

I know how to take a Python program and run it as a service but how would I write a Python program that can be installed?

My operating system is Ubuntu 18.04.
I'm developing a WxWidgets application under Ubuntu and I'm using CodeBlocks as IDE.

I need to:

  • read the data stored in a magnetic card band
  • check if they are OK
  • parse the string in order to get the code, the name and the surname

I'm using a USB magnetic card reader and I set a TextCtrl as "focused" so it immediately gets the data from the reader automatically.

The format of the string is like this:

%URSMCC84R04E815LURSO  MARCO_ò8038001605011036724_

Open in new window

The control characters are always the same and I need to read everything between % and _.
I need to obtain three strings:
  • the first one containing the first 16 chars
  • the second contains the surname which goes from the 17th till the first space
  • the third string contains the name and goes from the first char after the space till the _

What is the best way to do this in Wxwidgets?
Moreover, since the reader emulates a keyboard, the output string is read a char at a time, so how can I design the parsing code?

This is the code I'm using to read the string.

void ProjectFrame::OntesseraText(wxCommandEvent& event)
    wxString stringa_tessera = tessera->GetValue(); // I read the string coming from the USB reader
    TextCtrl2->ChangeValue( stringa_tessera ); // I load the string in the second TextCtrl just for test

void ProjectFrame::OnTextCtrl2Text(wxCommandEvent& event)
// TextCtrl used to display the parsed string

Open in new window

I see that there is a class wxStringTokenizer, should I use it?
I'm sorry but I'm just a beginner :(

Thank you!
Should you be charging more for IT Services?
Should you be charging more for IT Services?

Do you wonder if your IT business is truly profitable or if you should raise your prices? Learn how to calculate your overhead burden using our free interactive tool and use it to determine the right price for your IT services. Start calculating Now!

my printer is a brother hl-l2340dw.  i am using ubuntu as my OS.  is there something i should do to get this printer to work?  i am hoping to get around switching to Windows.  i don't like their updates very much.  where it tells you to not shut you're computer down.
How do I disable chef-client on a node?  7 days then autoenable is preferred.
Is gawk package installed in my linux laptop?  My linux distribution is Ubuntu 18.04 LTS

@system76-pc:~$ awk --version
awk: not an option: --version

@system76-pc:~$ which awk

@system76-pc:~$ apt-show-versions awk

Command 'apt-show-versions' not found, but can be installed with:

sudo apt install apt-show-versions
i have a very little script which is running when i use   $ ./check_dock
docker -com.... ok cpuuerc 0.xx%
 when i used in $ ./check_nrp -H "ip/localhost/" -c check_dock
return:  NRPE: Unable to read output
all other command i defined in nrpe is running.
What i missing here?

my check_dock scripts is:
#!/bin/bash -el
# Author: Bahman Sharzad
# Mail: bshmsn.sharzad@process-factory.dk

alias direc="cd /usr/local/nagios/libexec"
# . check docker container
statu=$((sudo /usr/local/nagios/libexec/check_docker -n $1 -c 80,90) | awk '{print $2}')
#echo $statu
all=$(sudo /usr/local/nagios/libexec/check_docker -n $1 -c 80,90)
#echo $all
if [ $statu = 'WARN' ]; then
        echo $all
elif [ $statu = 'CRIT' ]; then
        echo $all
elif [ $statu = 'OK' ]; then
        echo $all

and command in nrpe is
command[check_dock]=/usr/local/nagios/libexec/check_dock docker-compose_mongodb_1
i run command :  $ sudo ./check_nrpe -H -c check_dock
NRPE: Unable to read output
I remotely connect to Linux VM from windows PC puTTy terminal or remote desktop connection.  The version is Ubuntu 18.04.2 LTS.  It is 64-bit.

How to find out if this Linux distribution has xz-utils package ?
I connect to remote Linux VM from windows PC puTTy terminal or remote desktop connection.

Linux distribution version is:  Ubuntu 18.04.2 LTS
Does this distribution contain "build-essential" package?

What tools does "build-essential" package contain?

Does "build-essential" package include g++, gcc, make?  What other tools does it include?
I connect to remote Linux VM from my windows PC puTTy terminal or from remote desktop.

The Linux VM distribution is Ubuntu 18.04.2 LTS.  It is 64-bit.

How to find out if gcc-multilib is installed in my Linux VM?
i install nextcloud (16.03) on ubuntu. i try to setup mail function as:
send mode :smtp
 encryption :STARTTLS
serveradress: smtp.gmail.com port:587
(attach file)
i have error: A problem occurred while sending the email. Please revise your settings. (Error: Expected response code 250 but got code "530", with message "530-5.5.1 Authentication Required. Learn more at
 530 5.5.1 https://support.google.com/mail/?p=WantAuthError m11sm3234263lfk.56 - gsmtp

Any idea?
i set less security app on google account
I use "Remote Desktop Connection" from my windows PC to connect to remote Linux Virtual Machine running Ubuntu 18.04.2 LTS.
I open terminal window and type following command to clone git repository:

git clone git://git.yoctoproject.org/poky_local_copy

The response is as follows:
git connection failed
I open Mozilla Firefox Web Browser, enter git.yoctoproject.org and connect.  Why Web Browser connects to this site but from terminal cannot connect to this site?
CompTIA Cloud+
LVL 13
CompTIA Cloud+

The CompTIA Cloud+ Basic training course will teach you about cloud concepts and models, data storage, networking, and network infrastructure.

i have a ubuntu lxd container (on ubuntu 18.04).
i add a domain group in visudo. and run lxc set security.priviliged true on my lxd docker.
i try to update ubuntu 16 as domain user in sudores group:
return error : sudo apt update
sudo: unable to resolve host “my-host”
sudo: no tty present and no askpass program specified.
Hi Experts,

I get the following error when I convert tiff to jpeg with wand (python library) of imagemagick on linux ubuntu machine

wand.exceptions.CoderError: Read error at scanline 3373; got 27894 bytes, expected 30000. `TIFFFillStrip' @ error/tiff.c/TIFFErrors/568

Open in new window

When I open image with paint and convert it jpeg it is working fine.  But when I do it programatically it is throwing these errors.  Please help in resolving this issue.

Thank you

how to install lxd container in non default directories on ubuntu 18.0.3 server?
i try to join ubuntu 18.0.4 server to my samba rfd... domain via sssd
but sssd failed to start :
Failed to read keytab [default]: No such file or director
Exiting the SSSD. Could not restart critical service [domain]
sssd.service: Main process exited, code=exited, status=1/FAILURE
sssd.service: Failed with result 'exit-code'.
Failed to start System Security Services Daemon.

i don't forgot to unmounted my nfs connection before i remove disk and i have a directory archive like this
 d????????? ? ? ? ?            ? archive
i can't remove directory i can't change permission (chmod or chown)
i ca't find a process to kill.
how to resolve this issue?

My company site is currently hosted on windows IIS web server  called  bob.com (for example). I have setup a separate test site that is on a ubuntu apache server hosted on a different cloud provider.
I want to edit the virtual host configuration on my test site (apache) to be a subdomain of my production website. So on the test site it will be test.bob.com. Is it enough/correct way to change the ServerName to bob.com and the ServerAlias to test.bob.com ? The reason I want to edit the virtualhost config is in order that I can put an ssl cert on test.bob.com
Are there any security concerns/ will there be any connection issues?

Thank you.






Ubuntu is an open source software operating system that runs from the desktop, to the cloud, to all your internet connected things.