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Linux is a UNIX-like open source operating system with hundreds of distinct distributions, including: Fedora, openSUSE, Ubuntu, Debian, Slackware, Gentoo, CentOS, and Arch Linux. Linux is generally associated with web and database servers, but has become popular in many niche industries and applications.

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We have a vendor who has put his linux based appliance behind a firewall. If I ssh to the system from the same subnet as the linux appliance ssh succeed - giving me a login prompt and then succeeding with authentication. If I login to the linux appliance from the Outside of the firewall the conversation succeeds apparently - I get a login prompt. But when I enter the same credentials the connection is promptly terminated. If I look at the firewall I see only the allowed SSH session and no other denies to the server.
Any idea what might be going on? What logging could be looked at on the linux appliance to give us insight as to why the ssh connection is failing in the second case? Thank you
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Free Tool: Port Scanner

Check which ports are open to the outside world. Helps make sure that your firewall rules are working as intended.

One of a set of tools we are providing to everyone as a way of saying thank you for being a part of the community.

Hi experts,

My Ubuntu is currently in 14.04.1. I like to upgrade my system to latest LTS version using "do-release-upgrade" command. I am wondering this "do-release-upgrade" will go directly to 16.04 (1-time upgrade) or 15.xx first then 16.04 (need upgrade step by step)?

Do you have an idea how long is for this kind upgrade process?

thank you for your help.
I've been using phantomjs to convert HTML pages to PDF.  On my Mac, everything was OK.  But, on a Linux environment, the fonts were not rendering properly (particularly web fonts).  There isn't too much out there on this problem, until I finally stumbled upon this github issue: https://github.com/wkhtmltopdf/wkhtmltopdf/issues/45.  (Apparently, the workaround found for wkhtmltopdf also applies to phantomjs).  Anyways, the fix finally ended up to be creating a new file (/etc/fonts/conf.d/100-smoothfonts.conf) with the following contents:

<?xml version='1.0'?>
<!DOCTYPE fontconfig SYSTEM 'fonts.dtd'>
 <match target="font">
  <edit mode="assign" name="rgba">
 <match target="font">
  <edit mode="assign" name="hinting">
 <match target="font">
  <edit mode="assign" name="hintstyle">
 <match target="font">
  <edit mode="assign" name="antialias">
 <match target="font">
  <edit mode="assign" name="lcdfilter">

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Just throwing this out there in case someone else has the same issue and stumbles upon this post!
winscp how to save shared bookmarks shortcut

i was referring below but no complete info

I am writing a program in C to mimic a simple shell interface however I have a small bug in my code which I cannot figure out. When I run the program in background it starts to execute but when I press enter (instead of prompting me to enter a new command), it goes in an infinite loop which I dont understand why. Can someone please tell me what I am doing wrong here?

Replit link for the program https://repl.it/MrPH/3

Program to mimic linux shell interface
#include <stdio.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <unistd.h>
#include <string.h>

#define MAX_LINE 80 /* The maximum length command */

int main(void){
  char *args[MAX_LINE/2 + 1]; /* command line arguments */
  int should_run = 1; /* flag to determine when to exit program */
  char user_input[MAX_LINE]; 
  int i = 0;
  int background = 0;
    printf("OSH> ");
    scanf ("%[^\n]%*c", user_input);

    i = 0;
    args[i] = strtok(user_input," ");
    while (args[i] != NULL){
      args[i] = strtok(NULL, " ");

    if(strcmp(args[0], "exit") == 0) /* exit command */

    if(strcmp(args[i-1], "&") == 0){ /* if & is included process running in background*/ 
        args[i-1] = NULL;
        background = 1;

    pid_t pid; 
    pid = fork(); /* fork child process */
    if(pid < 0){  //if fork failed due to some reason 
        return 1;
    if (pid == 0){
        execvp(args[0],args); /* execute the 

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like a full clone in VMWARE , is there a way to do this?

I am having this issue that I have ( I think ) trased to an AMAZON ami that has changed and does not allow SSH anymore

can I access an older version of an AMI ????

CentOS Linux 7 x86_64 HVM EBS 1602-b7ee8a69-ee97-4a49-9e68-afaee216db2e-ami-d7e1d2bd.3 (ami-6d1c2007)

west coast AMI

(cannot SSh)

CentOS Linux 7 x86_64 HVM EBS 1602-b7ee8a69-ee97-4a49-9e68-afaee216db2e-ami-d7e1d2bd.3 (ami-af4333cf)

I work in an environment  consisting of Windows and Linux (CentOs) servers.

I would like to implement a central management system that supports LDAP.

In this case it would be Active directory.

I would like the following available to both LINUX and Windows servers:

1. Single Sign on
2. Password management - by extending group policy settings to both Windows and Linux, but managed through a GPO
     a. Password complexity
     b. minimum password length
     c. password history
     d. minimum password age
3. Create security groups and extend the groups to both Windows and LINUX servers (access rights to shares and folders)
     e. maximum password age

Can these settings be managed through Windows AD and extended to LINUX lcients if they are part of the domain?

I have looked at SAMBA and SSSD, but I am uncertain how to accomplish the requirements.

Any advice would be greatly appreciated.

Thanks in advance.

On a SLES 12.2 system I have a problem with BtrFS, especially with btrfs-balance (and probably btrfs-scrub).

The application running on that server is kind of sensible against server load, especially disk access and probably CPU load.

The system runs on (as recommended by the installer) BtrFS, which needs cyclic maintenance with btrfs-balance and btrfs-scrub. Unfortunately these processes generate excessive disk load and CPU usage for about 40 seconds.

I've done some measures to lower the impact of that - which helped to a certain degree - but one idea is left open:

The system has plenty of CPU cores available, and the idea is to isolate on CPU for running that process. I'm aware that I can restrict a process to one CPU easily with i.e.
taskset -c <CPU#> <command> <options>

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which I have tried successfully with btrfs-balance and btrfs-scrub.

Now I'm stuck on how to tell the kernel to spare that CPU core from being used by any other processes ...

Any hint ?
I need to migrate a Wordpress instance to a new server

Current Server is Wordpress 4.8.2 frontend and Ubuntu 12.04.5

I need to migrate it to a new server running Ubuntu 16.04.3 lts

So far I cannot find any info that specifically details this action.

Any ideas ?
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Hello Support

The attached download enables the ability to convert JSON file format to HCL format (which is developed by a company called Hashicorp.

There is a readme included in the download to describe how to carry out the conversion. However, the demonstration shows how to carry out the conversion in Linux. Unfortunately, I don't know Linux. Therefore, I was wondering if someone could show me how to carryout the conversion in Windows? If not, if someone to talk me through in simple terms how to carry out the conversion in Linux that would also be great - but as I mentioned I'm not a Linux person.

Your assistance will be greatly appreciated.


Linux common maintenance command records
I am using Debian 7.11 on this particular system. I have open media vault installed on it, but have lost the password. The system asks me for the open media vault root password every now and then, especially when performing tasks in the GUI of the Debian desktop, like rebooting the system or mounting a disk. I usually work around the issue by using the command prompt, where I have a sudo user and the root password of the Debian system.

So how do I recover or reset the root password of the open media vault installation?

i am going through below link

when to use fgrep and when to use grep ?
are there any advantages, disadvantages on over other?
please advise
I've installed Kali Linux as a VM on a high end Windows 10 Pro 64 system.
Unlike Windows XP and Windows 7 VMs, this one runs slower than as if it were running from a live CD.
I've tried two versions, the 64-bit download and the Offensive Security Kali Linux 64 bit VM which comes as a vmdk.
They were equally ..s..l..u..g..g..i..s..h.. to the point that they are virtually unusable.
Any thoughts or suggestions?
How to get cpu serial number in linux from cmd

Author Comment

by:Rajat Kumar Sahgal
i already tried with google & dmidecode -t processor but unable to get it .

# dmidecode -t processor
# dmidecode 2.12
SMBIOS 3.0 present.
# SMBIOS implementations newer than version 2.8 are not
# fully supported by this version of dmidecode.

Handle 0x0073, DMI type 4, 42 bytes
Processor Information
        Socket Designation: SOCKET 2011
        Type: Central Processor
        Family: Xeon
        Manufacturer: Intel
        ID: F1 06 04 00 FF FB EB BF
        Signature: Type 0, Family 6, Model 79, Stepping 1
                FPU (Floating-point unit on-chip)
                VME (Virtual mode extension)
                DE (Debugging extension)
                PSE (Page size extension)
                TSC (Time stamp counter)
                MSR (Model specific registers)
                PAE (Physical address extension)
                MCE (Machine check exception)
                CX8 (CMPXCHG8 instruction supported)
                APIC (On-chip APIC hardware supported)
                SEP (Fast system call)
                MTRR (Memory type range registers)
                PGE (Page global enable)
                MCA (Machine check architecture)
                CMOV (Conditional move instruction supported)
                PAT (Page attribute table)
                PSE-36 (36-bit page size extension)
                CLFSH (CLFLUSH instruction supported)
                DS (Debug store)
                ACPI (ACPI supported)
                MMX (MMX technology supported)
                FXSR (FXSAVE and FXSTOR instructions supported)
                SSE (Streaming SIMD extensions)
                SSE2 (Streaming SIMD extensions 2)
                SS (Self-snoop)
                HTT (Multi-threading)
                TM (Thermal monitor supported)
                PBE (Pending break enabled)
        Version: Intel(R) Core(TM) i7-6950X CPU @ 3.00GHz
        Voltage: 1.2 V
        External Clock: 100 MHz
        Max Speed: 4000 MHz
        Current Speed: 3000 MHz
        Status: Populated, Enabled
        Upgrade: Socket LGA2011-3
        L1 Cache Handle: 0x0070
        L2 Cache Handle: 0x0071
        L3 Cache Handle: 0x0072
        Serial Number: Not Specified
        Asset Tag: Not Specified
        Part Number: Not Specified
        Core Count: 10
        Core Enabled: 10
        Thread Count: 20
                64-bit capable
                Hardware Thread
                Execute Protection
                Enhanced Virtualization
                Power/Performance Control

Expert Comment

by:Ole-Aleksander Forchhammer
What distribution of Linux are you running?

When Bacula 5.2.5 Ubuntu is trying to backup directories with spaces in their names
(only when defined in FileSet), I'm getting error message:

storage-fd: Could not stat "G:/ ARC" ERR": The system cannot find the file specified.

This is within the Fileset.

Exclude {

          File = "G:/ARC DATA/onenote"

The space is between ARC and DATA.
As this is coming from Windows, there are  many similar names with spaces embedded. I have tried with and without quotes, but it makes no difference.

Has anyone any ideas.


Hi Everyone,

I have a question to find some simple clarification.
I did do a upgrade of VTiger 6.4 to 6.5 and get a deadlock error when creating a new lead. After researching I saw that it could have something to do with the vtiger_version.

I did restore it all back to Version 6.4 and all if running fine there. Before I retry the upgrade from 6.4 to 6.5 I noticed that the vtiger_version table indicated the following:
old_version: 5.4.0
current_version:  5.4.0

This VTiger install was initially installed on 5.4 years ago. Than it was upgraded to version 6 by and later to 6.4.

Long story short, my question is: As I am running version 6.4 now for many month, but what should the correct vtiger_version table say? Its clear it should be current_version:  6.4.0 but what should be in old_version? Should it be 6.0 since I uprated from 6 to 6.4 or should it contain the original installed version which was 5.4.0? or maybe 6.4.0 as this is what I run now.

I hope the question makes sense.
Warning: If your device uses WiFi, it's at risk!
News broke today about the Krack Attack, a new cyber threat that can decrypt and potentially view everything users are doing online. The Krack Attack preys on a weakness in WPA2 protocol. Hackers near the vulnerable devices (Android and Linux are at greatest risk) can retrieve sensitive user data and information.
Steps to Protect:
1. Apply patches as they become available. For phones and computers, the patches will come in the usual update format. For wifi routers, the manufacturer's website will have the patches.
2. Don't use public WiFi, especially for sharing or sending any sensitive information.
3. Double check that you are browsing with HTTPS. If you are unsure, install this plug-in to encrypt your communications with major websites and make your browsing more secure. https://www.eff.org/https-everywhere
4. Otherwise, use Ethernet.

For more tips on how to protect yourself: https://techcrunch.com/2017/10/16/heres-what-you-can-do-to-protect-yourself-from-the-krack-wifi-vulnerability/
Free Tool: SSL Checker
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Free Tool: SSL Checker

Scans your site and returns information about your SSL implementation and certificate. Helpful for debugging and validating your SSL configuration.

One of a set of tools we are providing to everyone as a way of saying thank you for being a part of the community.

I am using a variant of blackfin linux.  I am new to it and reading so much documentation.  What is the command needed to reboot.?

We have a program that needs to bind with port 44440, but when we try to use it says port is not available, but no other processes are using.   Does Linux restrict anywhere ?
On SLES 12.2 I do the following as root user:

mkdir -p /some/directory/ramdisk
chown -R simpleuser:users /some
chmod 777 /some/directory
chmod 777 /some/directory/ramdisk

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Then I add this to /etc/fstab:
ramfs /some/directory/ramdisk ramfs defaults 0 0

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followed by
mount /some/directory/ramdisk

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What I expect is a ramfs mounted to /some/director/ramdisk, owned by simpleuser and users, with permissions set to 777.

Surprisingly, after rebooting the machine, the owner of /some/director/ramdisk is root:root, and the permissions have changed to something more restrictive. I deem that more of a feature  than a bug, but that behaviour is really annoying in the environment I use it in.

Currently I do an explicit change of ownership and permissions prior to starting the application that uses the ramdisk (in the respective script, with sudo), but I deem that not very elegant.

Any hint what causes the changes, and how to prevent them ?
Where is the Keystone configuration file located?

a. /etc/keystone/keystone.conf
b. /etc/keystone.conf
c. /etc/openstactl/keystone.conf
d. /etc/keystone/service.conf
our lab recently has a new Ubuntu (14.04.1) machine but many of software package is out of date.
I try to update it before upgrade to Ubuntu 16.04. However, there is always problems for the command "sudo apt-get update"

I have googled this problem and change "/etc/apt/sources.list" several times, but the error still exists.
I am thinking the error may come from => Could not resolve 'hcapxb01'
I have no idea about the 'hcapxb01'.  My machine has internet connection but I can't ping or nslookup the  'hcapxb01'

Experts, please help me to slove "sudo apt-get update" error. Thank you
Sysadmin is complaining that when traffic to his server is a little higher than usual (say 300Mbps on a 1Gbps interface) that he's seeing Rx errors on his interface. If I look at the switch that is connected to his server it shows everything clean. No errors Rx/Tx - just an increase in throughput once a day. It's a linux system. What can I advise him to do regarding errors on higher than average throughput? Anything else I could do on the Cisco switch side?






Linux is a UNIX-like open source operating system with hundreds of distinct distributions, including: Fedora, openSUSE, Ubuntu, Debian, Slackware, Gentoo, CentOS, and Arch Linux. Linux is generally associated with web and database servers, but has become popular in many niche industries and applications.

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