Newest Questions

Q&A for system and network administrators

Asus RT-AC3200 Shibby Firmware Flashing Tutorial

I tried to Flash the latest shibby Build of the Tomato Firmware to my RT-AC3200 Router. If you Updated accidentally to the latest Firmware from Asus, you can not Upgrade to shibby via the Webinterface ...

How do you port forward packets coming from a tunnel on a VPN Client?

I have a network of OpenVPN clients where I wish to open a port that forwards traffic coming from the OpenVPN Server to another device connected to the client. The client is a router running OpenWRT ...

KVM virtual machine won't start and gives the following error

I have a kvm virtual machine with a web-server. Yesterday, without doing any modification on the server or the host, this virtual machine stopped responding. As far i can see it freezes at boot time, ...

nslookup fails but PowerShell's resolve-dnsname works

This is not a domain I have anything to do with, but I don't understand what's going on. The nameservers for sciencedaily.com are: ns-1414.awsdns-48.org. ns-1618.awsdns-10.co.uk. ns-300.awsdns-37.com....

ICMP/Internet checksum if packet entirely constists of zeros

We are currently investigating a strange behavior of different devices: if we send "empty" ICMP packets (that is, ICMP-SEQ and ICMP-ID are 0x0000 and no ICMP payload), for example using nping --icmp ...

Backport locale to earlier Windows version

I have written an application which contains language files localized in ru-MD (Russian as used in Moldova) and ru-RU (Russian as used in Russia). According to this table, the locale ru-MD is ...

Gets “POP before SMTP” still done today? [on hold]

I thought POP before SMTP is dead since smtp-auth is wide spread. Am I wrong? Is "POP before SMTP" done by well-known providers?

best practises to get the best performance of esxi on desktop grade pc [on hold]

I want to convert an existing desktop pc into an esxi server. So I acutally have a decent machine to do testing on instead of waiting 1/2 hr for the bloody server to warm up. NOt kidding! Intel I5-...

Cluster office workstations when not in use? [duplicate]

We've got around ~15 relatively decent Windows machines in the office and I'm wondering if it's possible to set up a system that clusters them as a single virtual machine when they're not in use ...

Rundeck mail config issue

i configured my Rundeck's mail settings, but i still got this message: 2017-02-23 10:54:06,796 [quartzScheduler_Worker-1] ERROR grails.app.services.rundeck.services.NotificationService - Error ...

IIS 8 on Windows 2012 R2 asks client for a cetificate

I have newly installed Windows Server 2012 R2 with IIS 8. I have added a SSL certificate through pfx file and when I try to access the site with browser I get this promt that asks client for ...

Aggregating logs in AWS CloudWatch

I have a web request log with the following structure: [ts, app, controller, action, method, url, elapsed] I would like to see requests that are taking elapsed > 1000 grouped by app, controller ...

Why does a RewriteCond %{REQUEST_URI} interfere with a second NOT condition?

At first the rule that works: ErrorDocument 403 /form.html RewriteCond %{REQUEST_URI} ^/index\.php$ RewriteCond %{REQUEST_METHOD} !POST RewriteRule . - [F,L] This means http://example.com and http:/...

Generate multiple Bash options from a text file?

I have a command that takes domain names as options. I have a long list of domain names to include and so I'd like to automate the parsing of that list of domains into the command. For example, the ...

Can I safely remove all mail services from CentOS?

I've inherited 3 legacy shared servers all running CentOS. We no longer offer any email subscriptions from our servers and have migrated everyone to cloud services. These servers host about 60 ...

Limit linux file cache memory usage (to avoid hypervisor memory exhaustion)

I have a server with 16GB RAM running several linux virtual machines (around 10), which perform several different tasks. These machines, with the default configuration, will fill up the memory I give ...

Give server accounts to webmasters

I create a system for multiple web masters for storing and serve their websites. They have their linux accounts and home directories. Their public_html folders are linked via ln -s command to ...

Keytool frequently uses up all server resources

On our RHEL servers, keytool now and then eats up all available resources. This seems independent on the Java version. PID USER PRI NI VIRT RES SHR S CPU% MEM% TIME+ Command 14103 root 20 ...

Board support differences between CentOS and RHEL

On SuperMicros site in OS support, there are boards that support RHEL of version X but not CentOS of version X and vice versa. I have encountered such problems my self. My question is how and why is ...

CentOS 7 LDAP SSH Error “cannot find name for group ID”

I'm running a CentOS 7 VirtualBox instance. I have LDAP authentication set up through our company Active Directory server. Note: The AD server DOES NOT have Unix extensions installed. What I'm ...

How to verify mysql single process with multiple threads model?

It is said that MySQL handles connections, allocating one thread per connection to the server,and MySQL is a single process with multiple threads. Now in my localhost . There are two connections to ...

How to block access to a website by its dedicated IP address? [duplicate]

Guys I currently own a dedicated server with cPanel / WHM installed on it . I have a problem though . When I assign a dedicated IP address to a user , people can view their website by opening their ...

Server restart on code change in vps? [on hold]

I'm running Django on a Ubuntu 16.04 LTS VPS with Apache2. The issue is I need to do a hard restart everytime I make code changes to take effect. Why is it that and do I solve the issue?

failed (111: Connection refused) while connecting to upstream

wget -SS https://www.example.com --2017-02-23 15:48:36-- https://www.example.com/ Resolving www.example.com (www.example.com)... <edited_ip> Connecting to www.example.com (www.example.com)|<...

NUMA node interleaving doesn't work for MariaDB

Please help activating NUMA node interleaving for MariaDB. Using MariaDB 10.1.21 on CentOS Linux release 7.3.1611. Per instructions on https://mariadb.com/kb/en/mariadb/systemd/ added /etc/systemd/...

SQL Server 2014 Express SSL certificate

I have a problem connecting to SQL Server 2014 Express. The server is installed on Windows 2008 R2 and: all parameters regarding forcing SSL are disabled (both on clients and server) clients ...

How to create a non-caching fast nginx reverse-proxy?

Nginx should be fast - at least people say so. I can't get nginx fast. For benchmarking, i use siege in multiple configurations for simulating high loads. So i tried to load-balance a single server (...

Duplicate a folder (size 150MB - 200MB) of one S3 bucket to another S3 bucket of different region using PHP

I want to copy a folder (size 150MB - 200MB) of one S3 bucket to another S3 bucket of the different region using PHP or in S3 term "duplicate all objects with the prefix of an S3 bucket into objects ...

NFS troubles: showmount -e {server IP} doesn't work

I'm having a number of troubles setting up an NFS mount on a Ubuntu server, and the main issue seems to be in making connection from the client (a Mac). I can ping the server address fine. Here is ...

Daisy Chain HP D2600 HDD Array

So I've searched to see if anyone's tried this and it doesn't seem like they have (if they have they haven't documented it) Setup 2 X HP ProLiant DL380 Gen 9 that share a HP MSA2040 SAS Dual ...

Query regarding what gives users permisson to log onto Windows Server

I am relatively new to Windows Server and would like someone to confirm if my understanding of the permissions required for users to logon to a Windows 2008 R2 server on a Windows domain is correct: ...

Cannot assign to variables in other namespaces

i've got main puppet class which is added to all servers in my network, let's call it: profile::base.pp: class profile::base { ... $agent_zbx_templates = ['OS Linux'] ... include profile::zabbix::...

iLO and DNS - how does it work?

How does host name resolution work on a server's iLO port? For example, in case of a HP ProLiant server equipped with iLO, I can access the iLO web interface through a factory-set hostname URL http://...

ERR max number of clients reached on a redis machine, how can it be fixed?

I'm in a customer's site, fixing some monitoring related issues. The servers in the site are configured to collect application metrics with Statsd and system metrics with Sensu. Then Sensu is used ...

How ssh work with RSA and DH [on hold]

I have heard SSH use RSA and diffie hellman. I have also known the key exchange process as following. 1. Client init 2. Server init 3.Key exchange request 4. Reply 5. New keys It use DH during key ...

Corosync resource keeps moving after failed node is online again

I have a 2-node corosync cluster managing a virtual IP and an asterisk resource. When I shutdown one of the nodes (server2) intentionally (as a disaster recovery test), the first node (server1) takes ...

kubectl: The connection to the server XXX.XXX.XXXXXX was refused

I am trying to connect to kubernetes master (cluster) in Google Cloud Engine. The error that always I get when the kubectl try to access to kubernetes master is: The connection to the server XXX....

How to debug slow response time when load average is already low?

i notice certain delay/lag when navigating the site but load average of the server is low (around 1.5~2). So my question is where can i look for the cause of this delay that happens right after ...

Issue in setting up mail server on digital ocean? [duplicate]

I am newbie to digital ocean and want to setup fully configured mail server for email transactions. Digital ocean uses SSH connection for security. I have installed Postfix on my server and used s-...

Nginx server host header server_name

In this tutorial it is written that after matching against the listen directive, nginx will match agains the server_name directive, which can be either an ip adress or a domain name. But how will it ...

OpenDKIM record DNS query works only sometimes, seemingly randomly

My server is modalduality.org and I have a DKIM record at 201703._domainkey.modalduality.org. When I run dig 201703._domainkey.modalduality.org TXT I get back the correct record in the ANSWER ...

Finding XP boxes on our intranet

We're out on a mission to find and eradicate XP boxes on our intranet. Now we're wondering what the fastest (scan) method might be --XP boxes connected to our active directory have already been ...

Layer 3 IP Forwarding/NAT between two interfaces

I have a strange configuration, let's see if you can give me some advice :) I have two networks (10.X/24 and 20.X/24) conected by a linux machine between them. This linux have two interfaces, each ...

How do I upgrade JetDirect on an HP LaserJet 4000

I have a trusty HP LaserJet 4000 with a JetDirect Network card installed. I have followed all the documentation provided by HP and I've been unable to succesfully upgrade the firmware to a newer ...

ILO Update : Which version should we select?

We have a HP ProLiant DL160 Gen 8 server, with VMWare ESXi 6.0.0 actually installed on it. We started to update it to VMWare ESXi 6.5, but the upgrade stopped, stating that we need to update the HP ...

Possible performance matrices for AHP based objects ranking [on hold]

I am working on objects ranking by a dynamic algorithm which focuses on Multi-criteria Decision making approach using Analytic Hierarchy Process (AHP) with multiple experts opinions. What performance ...

Removing a AAAA record - is this safe to do?

For our domain we currently have both A and AAAA records configured. We would like to switch the IP to which these records point to. For this purpose, we have purchased a 'dynamic IP' service from ...

Multi domain SSL not working with www on SAN

I am using godaddy multi domain SSL on windows server 2008 with IIS 7.5. My main website www.abc.org working fine with www and non www but other domain ex. DNS Name=www.abc.org DNS Name=abc.org DNS ...

Authenticated External SMTP Relay

Description I am trying to use "Default MAIL-SERVER" (port 2525) receive connector as an authenticated external relay. I am successful with the mailbox "Bob.smith@domain.com" but I am unable do it ...

Apache (2.4 Debian Linux) VirtualHosts just stopped working

Hope someone can help. All my virtualhosts just suddenly stopped working and all hostnames go to the default virtual server. I'm using Webmin mostly to administer and it shows all virtual hosts okay. ...
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