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

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How to test disk latency on Linux?

Made an upgrade of RAID firmware and latency as it seems have increased. Could you please advise on the most accurate way to examine disk read and write latencies?
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1answer
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Multiple Reverse SSH Tunnels using Single Port

I am able to accept reverse SSH connections from multiple remote systems on a single server using a port for each connection: Remote A: ssh -fN -R5000:localhost:22 user@server-ip -p22 Remote B: ssh -...
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1answer
8 views

DH GEX group out of range

I'm having a sudden issue SSHing into my server: ssh -v --@-- OpenSSH_7.2p2 Ubuntu-4ubuntu1, OpenSSL 1.0.2g-fips 1 Mar 2016 debug1: Reading configuration data /home/paul/.ssh/config debug1: Reading ...
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0answers
8 views

Difference between ldap/ldap.conf and Samba4 smb.conf [on hold]

I have been using using Samba4 as domain controller, with active directory authentication for different services for a couple of weeks. I am wonder what is the difference between the CA which I can ...
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0answers
12 views

IPTABLES - IP Restricted Port Forwarding for RDP

I can't find an answered question for this problem. I have about 7 ranges of IP address i would like to allow to RDP(port 3389) to a a server within my network. My main router uses iptables and i ...
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0answers
17 views

chown: Operation not permitted for root on ext4 root-partition

After upgrading from Ubuntu v14.04 to v16.04 chown doesn't seem to work any longer on my server. I checked following: filesystem is RW user exists folder is not immutable all commands executed as ...
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1answer
9 views

MySQL won't allow login from normal user account

When connecting to MySQL as root from the linux user user user@computer:~/$ mysql -u root -p Enter password: ERROR 1698 (28000): Access denied for user 'root'@'localhost' When doing the same exact ...
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2answers
26 views

What does the sendmail daemon do exactly when it receives a kill -15 (SIGTERM) request? How does this affect messages that are in transit?

Can someone elaborate on what would happen if the sendmail daemon is in the middle of processing a message when it receives a kill -15 request? Would it finish processing whatever message it's working ...
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1answer
1k views

Intermittent NFS lockups on Isilon cluster

We have an Isilon cluster with 8 IQ 12000x nodes which exports storage via several NFS shares for a handful of Linux and Solaris clients. There is a Linux system that has one of these NFS filesystems ...
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1answer
12 views

AWS Cloudformation: Invalid template resource property error

I am attempting to create a Cloudformation template to configure an IAM role. As far as I can tell my JSON is 100% valid but apparently I'm overlooking something else because it's not able to be ...
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8answers
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Why would a server not send a SYN/ACK packet in response to a SYN packet

Lately, we've become aware of a TCP connection issue that is mostly limited to mac and Linux users who browse our websites. From the user perspective, it presents itself as a really long connection ...
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9 views

Restrict access to Linux via PAM with configured SSO

i have SLES 12 in Active Directory Domain. Single Sign On for SSH is configured. I want to allow access to server only to some AD groups via PAM (not only for SSH Service, ftp, etc.). I tried to add ...
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0answers
13 views

Unkown File permissions for /etc/resolv.conf

I am unable to ping any url (for example www.google.com), neither any of the website is working. However, I can ping static IPs (E.g. 8.8.8.8). A little debugging showed that the issue is /etc/resolv....
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0answers
25 views

Openvpn tap interface configuration gets self assigned IP

I have a strange misconfiguration on my openvpn tap network. Clients can connect and get there IP address in 192.168.42.x as intended, but after few seconds another address gets assigned to it, self-...
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2answers
2k views

Adding a new user into linux from a script

I am using a customized Redmine installation to manage projects. I have managed to hook the addition of new users and send the login information to a bash script I have. Below is my script: #!/bin/sh ...
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2answers
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postfix/dovecot says “postmaster_address setting not given” but it is

I'm trying to configure postfix and dovecot to work together with virtual domains stored in MySQL, but I keep running into this whenever mail is passed from postfix to dovecot. Apr 26 11:54:40 smtp ...
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1answer
12 views

sudo-like privilege management for docker containers

I want to allow a Docker container to invoke some actions on another container without granting it full privileges. An example would be a Docker container which does log rotation and reloads the ...
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5answers
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dd on entire disk, but do not want empty portion

I have a disk, say /dev/sda. Here is fdisk -l: Disk /dev/sda: 64.0 GB, 64023257088 bytes 255 heads, 63 sectors/track, 7783 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Sector size (...
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2answers
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Traceroute doesn't reach gateway

i have problem with my opensuse 11.3 network. So, i've assigned ip 192.168.137.2 to it, and another computer (win7) with ip 192.168.137.1 On the opensuse, the gateway is the 192.168.137.1. and the ...
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1answer
65 views

how to make a VMware clone into a running instance from the command line?

I am using VMkfstools and the vim-cmd suite of programs to clone Linux hosts. I'm trying to figure out how to turn a clone into a new running instance, but for some reason I'm not locating any ...
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1answer
3k views

How to get OpenVPN Client (Mikrotik RouterOS) <-> OpenVPN server (Debian/Linux) setup to work

I have some issues with making MT to work with OpenVPN server (Debian). I can make successfull connection to OVPN server, but traffic is not routed through OVPN server. Here is my configuration. ...
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4answers
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Is there a way to list all configurable `alternatives` (symlinks for similar commands) on the system?

The alternatives command (package chkconfig) on RHEL manages symlinks which link a generic name to one of the alternative implementations. For example, mta group of symlinks can be provided by ...
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0answers
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postfix mails stuck in mailqueue

I ran into a problem, I'm trying to set up postfix mail server (I'm using webmin), everything seems to work fine, I successfully connected outlook to POP3/SMTP, but as soon as I send an email, it gets ...
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2answers
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Unable to install asterisk-core on centos x86_64 [on hold]

I try to install on a linux Centos x86_64 a library named asterisk-core-11.20.0-1_centos6.x86_64 which not found the library libsrtp.so.0 present at the path /usr/lib/64. the error is: Error: Package:...
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2answers
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du command takes WAY too long to run

I am running du -sh in a variety of directories to find disk hogs. I got two identical servers (Dell PE2850s), both with RHEL5 and it will take significantly longer to run du on one server over the ...
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0answers
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Linux iptables to forward all traffic from one port to another ip [on hold]

I want to make so that iptables forwards all traffic from port 65535 to the LAN IP 10.8.0.2 How would I do that? I've tried these but they don't seem to work. iptables -t nat -I PREROUTING -i tun1 -...
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2answers
4k views

WMI: wmic linux agent query error: NTSTATUS: NT_STATUS_ACCESS_DENIED

Myself new to wmic and keep trying for a long time with default agent query approach. wmic is linux based WMI tool to talk to windows WMI agent. While trying to fetch data with wmic from nt(win7 with ...
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4answers
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In Puppet, how would I secure a password variable (in this case a MySQL password)?

I am using Puppet to provision MySQL with a parameterised class: class mysql::server( $password ) { package { 'mysql-server': ensure => installed } package { 'mysql': ensure => ...
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1answer
13 views

How to forward specific packets from a machine to another machine? [on hold]

I have a network with 3 linux hosts, A, B, and C. I want to send 1,000 packets from A to B, and B should automatically forward it to C. How should I do it? B has one adapter with IP 192.168.1.100/24 ...
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1answer
43 views

Gmail is blocking emails from my mail server ( Postfix ) CentOS 6

I'm unable to send emails from my mail server. I've tried every single possible solution I came across. Firstly, I WAS ABLE to send emails but they were going to spam so I decided to install OpenDKIM ...
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11 views

OpenVPN server to forward traffic to client

I've set up OpenVPN on my Debian server. I want all traffic that goes on the OpenVPN server on port 65535 to route to a client's port. The client is connected to the server using OpenVPN. But the ...
4
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1answer
4k views

Fresh Proxmox VE 2.1 installation with defaults can't be reached or pinged

I am using the lastest Proxmox VE 2.1. My server has two NICS with a uplink only connected into eth0. My Server is a co-located server utilizing public IPv4 IPs. It is not behind a firewall or any ...
0
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1answer
9 views

using umask to set default file settings [duplicate]

I am setting default umask of linux box for the first time. I log in as root user on a Centos 6 server. I want these default values: owner: read/execute/write (7) group: read/execute (5) other: ...
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0answers
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Force nproc ulimit on non interactive user

I have a script that can be launched n times at the same time through php-fpm. php-fpm pool is set to run under a certain username and I want to limit the number of processes this username can launch. ...
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1answer
28 views

Outgoing spam from postfix using my domains

I get a lot of spam outgoing from my server which uses fake emails but real domains (that are hosted on my server Linux Debian Squeeze). These all have "msg" plus a random number as Email address. ...
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1answer
2k views

Monit failed to start shell script

So I am having a problem with monit starting a process this is my code: check process program_1 matching "program_1" start program = "/home/user1/files/start.sh" stop program = "/home/user1/files/...
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1answer
37 views

Server under attack [on hold]

I've got a DigitalOcean Debian server. And since yesterday the CPU has been at 100%. I use it for testing at the moment. I'm a newb with servers, so really got no clue what to do. Can someone ...
1
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1answer
1k views

pam_tty_audit apparently not working

I just compiled pam_tty_audit module, because my Linux distro doesn't include it with the usual PAM modules. I included to the /etc/common-session the configuration line, as suggested in this ...
2
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1answer
23 views

CentOS: After Kernel Update system does not boot (/dev/md2 does not exist)

after doing a kernel-update (only via yum update) my centOS 7 (64bit) does no longer boot. I now booted into rescue-mode and tried to mount /dev/md2 - this worked fine: Any ideas what I could do ...
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1answer
17 views

OpenLDAP debugging logs

I have OpenLDAP version 2.4.40 which is being cross compiled for a different (proprietary) target. This has been in place and working fine for many years but now I find myself needing to get some ...
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1answer
18 views

How to setup NGINX to store multiple sites on the same domain? [on hold]

I have domain exampledomain.com with NGINX, it works. I have folder for static HTML/CSS/JS projects (SPA or MPA): /home/user/www. This folder contains 2 subfolders: project1 and project2. I want that ...
0
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1answer
1k views

Connection to linux server fails with filezilla

I am trying to connect Filezilla with my Amazon EC2 instance. I changed the settings in my security group to open port 22 SSH. Now I am connecting as follows:: File-> Site Manager > Host-- ...
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1answer
1k views

CentOS 6 init script doesn't work properly

I'm setting up my ruby production server based on CentOS 6. I need a process called god (which is a process monitoring tool) to start at boot. I'm using an init script that I found here. Just as ...
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1answer
15 views

remote script execution from local script linux doesn't stop for remote script prompts

script abc.sh is on machine M1 and xyz.sh is on machine M2 script abc.sh: #!/bin/bash ssh -l user1 host.com ./xyz.sh -b1 arg1 -b2 arg2 script xyz has certain user prompts like pwd etc When I ...
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1answer
31 views

Getting my server maintenance script right

I have two routine postgresql maintenance tasks that require deletion of aged rows from certain tables of my web application. Both take ~1 hr to complete, respectively. Currently, each of these ...
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3answers
3k views

Disable user_deny.db in Cyrus/imapd

We have a cyrus 2.4.12 on Debian, we use packages, rather than building each software ourselves. I am getting the this "log" constantly, a lot of, various users, and 8-10 times per user request: ...
0
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1answer
29 views

How to authenticate clients trying to access my website via my external IP address?

I have made a ruby on rails app which is running on 0.0.0.0:3000 I have also forwarded the port 3000 on my router so that it is accessible remotely via the internet. So, I can view the webapp by the ...