Questions tagged [linux]

Linux is the generic term for a UNIX-like open source operating system based on the Linux kernel.

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inux/unix Auto detection logic for physical keyboard layout

Anyone aware of a concise logic available to automatically detect my physical keyboard layout, so that I could do automatically set my layout table to the correct default. I'm aware that most distro-...
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1answer
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Unable to reach host with static ip and gateway is vlan - Debian 10

I have been trying to get static ip working on a Debian 10 install. The server is to operate in a VLAN separate from any other network. The VLAN id according to the router interface is 3. The router ...
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Very strange disk corruption error

I have a server, where I deleted a large file. Let's call it ~/tempfile.txt. Somehow, the deletion didn't work properly, and the disk got corrupted -- meaning, du -hs * doesn't show that file existing....
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Fedora Boot UEFI SLOW

After a fresh install of Fedora 31, the boot time is incredibily slow. I suspect something went wrong with the boot partitions. Here is the layout [root@linux Scaricati]# efibootmgr EFI variables ...
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How can I tell which version of CIFs is in the kernel if CIFs module isn't loaded?

I need to determine the CIFs version that exists in my kernel, but the CIFs module isn't loaded. my-user@ip-XX-XX-XX-XX:~$ modinfo kernel/fs/cifs.ko modinfo: ERROR: Module kernel/fs/cifs.ko not found....
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systemd rc.local race condition

Forgive me, I am newer to Linux/Debian/Raspian. The company I work for has a bash script being run from rc.local that updates /etc/hostname file on bootup of a raspberry pi based on the MAC Address ...
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MMCLI on BusyBox returns "Cannot request manual scan of devices: unsupported' - IMEI

I have a USB modem plugged into a BusyBox v1.23.2 appliance. Typically I would be able to get the IMEI number using the MMCLI command set. However when this specific card (multiple of the same card - ...
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1answer
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How can I change the sender's name for email messages sent by cron

We have several nearly identical servers with a fairly classic server-NN naming convention, each running cron jobs that we like to monitor via email. There are is a group of users, who receive the ...
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Schedulling tasks on different plateforms

We have a mix of Linux, OSX and Windows servers that use crontab, Windows Task Scheduler, etc to run a bunch of bash/windows scripts, rsync commands, etc. I would like to replace these OS specific ...
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Why are GPUs accessible from docker containers running on Linux hosts, but not on Windows or MacOS hosts?

Recent versions of docker (or any version of nvidia-docker) allow direct(?) access to the host GPU from within docker containers, with full access to CUDA APIs. This is very convenient when deploying ...
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How to make a discharge band width distribution between users with nginx?

On my server I have a 1gb file which can be accessed by a route by location / users, and download the file, the cuetion is how I manage to distribute the bandwidth according to the users who are ...
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OpenVPN - ERROR: Cannot open TUN/TAP dev /dev/net/tun: No such file or directory (errno=2)

There are lots of questions pertaining this error, and there is a suggested manual fix which works well, but there's no permanent solution. How can i permanently solve this? Im having this issue on a ...
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1answer
648 views
+50

Is there is any tool/way to find out why packet is getting dropped due to an arp cache full?

My developer hypothesis is packet is getting dropped at arp layer. We increased the default value of neigh.default.gc_thresh3 1024 --> 2048 and now everything looks good. But I want to understand is ...
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1answer
169 views

Bottleneck identification using iostat, vmstat, mpstat

I am doing some Apache and MySQL performance tests, then upgrading a single component and running tests again to see where the bottlenecks are. I have a local used server warehouse (Tams in Lindon UT) ...
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Mounting to existing point in Linux EC2

In my RHEL Linux EC2 i have 256 GB of volume attached. $df -h /dev/mapper/rootvg-rvg_usr 8.0G 5.7G 2.3G 72% /usr /dev/mapper/rootvg-rvg_usr 4.0 3.0G 1020M 72% /var Now i ...
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Where to install new versions of .Net Core SDK on Linux server?

As I understand it, new versions of the .Net Core SDK can be installed over older versions of the .Net Core SDK. I think I read somewhere that newer versions can build projects that target previous ...
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How to enable and disable IPv4 in linux system programmatically?

I am new to linux programming and based on some configuration parameter I want to disable and enable IPv4 on linux system programatically. The Pseudo-code of the solution would be like: if(...
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Essential sysadmin skills? [closed]

We are planning on offering a short, hands-on course on system administration. Target group is the sysadmin (or aspiring sysadmin) in a small shop. Think some 30 people in all, software development ...
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17 views

DDWRT x Linux server monitor traffic bandwitch

Good afternoon, I would like to monitor how much of my bandwitch each of my devices are spending per day, week and month. For that I have two options: 1 - use a DDWRT router or 2 - if it is possible, ...
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1answer
79 views

How to mount a LVM controlled ext4 file system stored on a AWS EBS volume built from a snapshot

I have a ext4 file system that is part of a Logical Volume and the underlying storage is AWS EBS. I took a snapshot of the EBS and then used that to create a new EBS volume and attached it to theEC2 ...
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Fail2Ban -> UFW -> IPTables (how to log blocks)

Running: Ubuntu 18.04.4 LTS Fail2Ban v0.10.2 ufw 0.36 iptables v1.6.1 I've successfully setup fail2ban to use ufw to block ip's based on ssh authentication failures. As we know, ufw is just a front-...
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1answer
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unable to connect to google cloud instance

I was unable to ssh my current instance so I created a snapshot of the disk in current instance. Then, used that snapshot to create an new instance. also, I changed the ssh login to os login for ...
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Issue with production kiosk setup with Chrome

We have 6 touch kiosk (4k resolution) running Ubuntu 18.04 Linux, Google Chrome browser and Vue.js application inside. Specification: PC: https://www.hpmarket.cz/productOpt.asp?konfId=4KX74EA 8GB ...
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How can I intercept a socket binding call to map to another port?

Let's assume I have some executable foo and I have bar. Both are hard-coded to listen on port 80. Let's assume we have root. How can I get both running on different ports? Or one of them? You can ...
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31 views

CGroup per application routing with iptables not working

Usage scenario: Shadowsocks Client ---> Shadowsocks Server (running on VPS A) ---> Wireguard VPN (running on VPS A) ---> Wireguard VPN (running on VPS B) Basically, I'm trying to setup an encrypted ...
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1answer
25 views

Internet connection slow in linux [closed]

I have a problem with my new internet connection. This is a symmetric 500Mbs connection but i only get 50M in my linux computer. In windows I get 500Mb for up and down with other computer. I know ...
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1answer
31 views

Change clock source in kernel stanza

I want to permanently change clock source in CentOS 7. I Found quite nice article here: https://access.redhat.com/solutions/18627 Permanently, adding clocksource= to the kernel stanza: title Red Hat ...
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1answer
35 views

Share applications to many computers using NFS

We want to set up a computer lab with about 10-15 PCs and to run Ubuntu at a college. Then, we want to install programs mainly for engineering/research/numerical computations. To ease the management ...
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Can no longer log into gcloud VM instance

I've logged into this computer 10 times. The instance is clearly started. It is worth pointing however that the last time I used the computer it crashed for stupid reasons. I got the error message '...
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1answer
27 views

What happens when ntp stops sync with remote ntp server and LOCAL (127.0.0.1) is also not defined in the ntp.conf

I wish to understand the scenario in which we have defined only remote servers in the /etc/ntp.conf file and we have not set the LOCAL ntp server (127.0.0.1) options. What happens in case of a ...
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41 views

Unable to connect by SSH to local vm's

I have some troubles to reach by SSH my local vm's running on a dedicated server with the following ip address 40.53.XX.XX. I set up a Nginx reverse proxy in front of the VM's. Hypervisor ip ...
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23 views

Compatibility with rc-local

Recently I faced issue with rc.local Compatibility. Does anyone had fixed this issue? loaded failed failed /etc/rc.d/rc.local Compatibility systemctl status rc-local.service "OUTPUT" : rc-...
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Unable to change password in Linux “Password has been used” [closed]

Currently we have a problem where we can't change the password of several users. When we try to change the password it gives us the following output "Password has been used" and the password of that ...
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3answers
170 views

How does Linux allocate bandwidth between processes?

If I don't set up any traffic shaping, how does Linux allocate (outgoing) bandwidth between processes? My specific situation is that I am running 30 identical processes on a cloud VM, each of which ...
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1answer
19 views

Unable to set bandwidth limit on ingress wireless interface with netem and ifb

I am trying to limit the bandwidth on the ingress of a wireless interface using an IFB virtual interface. I followed the instructions here Summary of the steps: Bringing up ifb: sudo modprobe ifb ...
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1answer
30 views

Restore root on LVM with one disk (seperate boot partition)

I did a stupid thing and accidentally removed my LVM partition in parted. Since this was a single disk LVM, parted rescue finds an EXT2 partition in the sectors, but I am unable to boot from that ...
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1answer
27 views

How can I have systemd auto-start a service after a manual service is started?

I have a server with an encrypted filesystem which must be manually brought online after a reboot. Some services require that encrypted filesystem to be mounted in order to read configuration/data ...
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9 views

How to exclude particular directory in Urban code Deploy with “Replace Token” function

I am using Urban Code Deploy to deploy the binaries and changing environment[DEV|UAT|PROD] specific variable using "Replace Token" functionality.In my include section "**/*" is found by default. This ...
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2answers
70 views

Need to capture UDP packets on a Linux router, modify them and send them to the original destination

I'm dealing with a legacy application that can't be touched. It sends UDP packets to addresses calculated from a client ID (yes, really: its basically something like 192.168.0.x, where x is the client ...
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11 views

Chinese character setting in putty not work

I need to display Chinese in putty and open a file in Chinese. As others mentioned, 1. locale setting ( LANG=zh_TW.big5 / LC_ALL=zh_TW.big5 ) 2. Putty > Changed Setting > Translation > ...
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1answer
35 views

SSH redirected to a different ip address after adding new iptables

I have some troubles to reach by SSH my dedicated server running on Proxmox hypervisor with the following ip address 40.53.XX.XX. There is my configuration: I have 3 VM’s running on it with a local ...
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0answers
26 views

Bonding / Link aggregation / NIC teaming for faster transfer

I am working on a server for costumer and want to utilize more than one 1Gb connection to servers, to make for instance 4Gb connection with 4 cables. My question is how to achieve this with Ubuntu ...
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1answer
47 views

bind9 not working when starting bind9 service but works when explicitly starting named

I have a really odd situation I don't fully understand. I have a master and slave DNS, I've checked the configuration, and no errors are returned. if I try to start bind9 as a service, it fails to ...
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28 views

Mail server setup for physically different imp and smtp

I wanna ready a mail server with linux based (Ex. Postfix/Qamil/Icewarp). For bulk users I want to keep physically separate the smtp server from imap. Main server will be imap. but how they do work. ...
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Google Compute Engine: /syslinux/vmlinuz.A has invalid signature

Since last week, my Google Compute Engine instances do not boot because of this error. [0m[37m[40m[0m[30m[40m[2J[01;01H[0m[37m[40m Booting `verified image A' error: /syslinux/vmlinuz.A has invalid ...
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1answer
96 views

How to Audit Linux Startup Scripts for Security

I'm in the process of migrating one of my Linux servers, and I noticed that I have supervisor running a startup script as root, but the script is writeable by a non-root user, which creates the ...
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1answer
28 views

Using auth0 on AWS EC2 in a Shiny app using RStudio

I am trying to use auth0 on AWS EC2 (Ubuntu) using RStudio using the R package - auth0. To make the Shiny app publicly accessible, I have the port 8100 (this is where the app is hosted) open to the ...
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0answers
14 views

New nginx server block doesn't seem to be doing anything

I'm fairly new to nginx - but I am using it successfully as a reverse proxy for two domains. I wanted to add a third in the same fashion, however despite this server block pointing at a different port,...
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1answer
161 views

fail2ban's database is too large (over 500mb). How do I get it to a reasonable size?

Recently my backups have started failing, and I tracked the problem to the file /var/lib/fail2ban/fail2ban.sqlite3. It is over 500mb. I am not sure whether it has been growing over time or if this is ...
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60 views

OpenSSL - Output PEM encoded part only when signing a certificate request

I've set up my own Certificate Authority based on a Debian 10 system and I can successfully sign certificates. But when I do so by using the command openssl ca -in /root/ca/certreqs/domain.tld.csr -...