Greatest Hits

28
votes
4answers
58k views

Postfix - how to retry delivery of mail in queue?

I have a backup mail server in case of a failure on the main one. In that case of failure, mails come on the backup server and stay there until the main one is back. If I wait some times, the ...
13
votes
7answers
49k views

Powershell: How do I query pwdLastSet and have it make sense?

I need to get the last password change for a group of account in an Active Directory security group, and I feel like this is something PowerShell should be good at. Right now, I'm already stuck at ...
9
votes
5answers
80k views

Can you use a USB hard drive in ESXI?

I know that you can install ESXi 4.0 on a thumbdrive, but I was wondering if you could plug in an external harddrive to give extra storage to one of your VMs? We run a fileserver inside of ESXi that ...
21
votes
6answers
77k views

Finding why a user is locked out in Active Directory

A user's account keeps getting locked out in Active Directory. It's probably caused by an app that's using Windows authentication to connect to SQL Server. Is there a way to find out which app is ...
21
votes
10answers
66k views

Which is better: RAID5 + 1 Hotspare / RAID6?

Just curious, I have 6 x 1TB 7200RPM Near Line SAS for my new server. I can either configure it as RAID5+1 Hot Spare or RAID6. What should I choose?
15
votes
4answers
38k views

How do I sleep for a millisecond in bash or ksh

sleep is a very popular command and we can start sleep from 1 second: # wait one second please sleep 1 but what the alternative if I need to wait only 0.1 second or between 0.1 to 1 second ? ...
15
votes
9answers
62k views

How do I make Linux recognize a new SATA /dev/sda drive I hot swapped in without rebooting?

Hot swapping out a failed SATA /dev/sda drive worked fine, but when I went to swap in a new drive, it wasn't recognized: [root@fs-2 ~]# tail -18 /var/log/messages May 5 16:54:35 fs-2 kernel: ata1: ...
178
votes
13answers
66k views

Any benefit or detriment from removing a pagefile on an 8GB RAM machine?

I'm running Windows 7 on a dual core, x64 AMD with 8GB RAM. Do I even need a pagefile? Will removing it help or hurt performance? Would it make a difference if this is a server or a desktop? Does ...
8
votes
8answers
52k views

SSL Error - unable to read server certificate from file

I've been setting up SSL for my domain today, and have struck another issue - I was hoping someone could shed some light on.. I keep receiving the following error messages: [error] Init: Unable to ...
14
votes
4answers
63k views

Is it possible to mount/unmount a physical hard drive in Windows XP?

Is it possible to mount/unmount a physical hard drive in Windows XP? Ideally, I'd like to be able to do this from the command line so that I could have batch files to do it, ie: mount.cmd unmount.cmd ...
117
votes
5answers
35k views

LVM dangers and caveats

I have recently started using LVM on some servers for hard drives larger than 1 TB. They're useful, expandable and quite easy to install. However, I could not find any data about the dangers and ...
23
votes
1answer
44k views

How do I change the privileges for MySQL user that is already created?

I understand how to create a new user with privileges, but what is the correct way to change privileges for users that are already created? We are running a DB audit and some of the users have way ...
63
11
votes
2answers
7k views

How can I tell if my website is vulnerable to CVE-2014-3566 (POODLE)?

Google announced a vulnerability in the SSLv3 protocol that ... allows the plaintext of secure connections to be calculated by a network attacker. This vulnerability has been given the ...
11
votes
4answers
61k views

What causes duplicate ACK records?

We're reviewing Wireshark captures from a few client machines that are showing multiple duplicate ACK records which then triggers retransmit and out-of-sequence packets. These are shown in the ...
15
votes
4answers
62k views

What's the maximum number of wifi connections for a single WiFi router?

We've got a Draytek 2829VN Wifi router and I'm wondering how many concurrent connections I should expect a router of this kind to cope with? We are looking to connect 60 iPads! I'd also be ...
26
votes
2answers
31k views

How to get the url of the current svn repo?

I have 2 svn checkouts that someone setup for me. Now I need to check these same files on another computer, but since I didn't check them out initially I don't know the urls to use when running the ...
40
votes
6answers
56k views

Should I use tap or tun for openvpn?

What are the differences between using dev tap and dev tun for openvpn? I know the different modes cannot inter-operate. What is the technical differences, other then just layer 2 vs 3 operation. ...
88
votes
2answers
30k views

How can I see which flags Nginx was compiled with?

How can I check what modules have been added to an nginx installation?
65
votes
1answer
40k views

What is a challenge password?

I'm setting up SSL on an Ubuntu server. One of fields it asks for as part of setting up the CSR is a "challenge password". What is that? The default is blank. Do I need to enter one?
56
38
votes
4answers
36k views

How to run a command multiple times?

Is there a way to run a command (e.g. ps aux|grep someprocess) for n times? Something like: run -n 10 'ps aux|grep someprocess' I want to use it interactively, please do not post scripts. ...
59
14
votes
7answers
60k views

Nginx + php-fpm “504 Gateway Time-out” error with almost zero load (on a test-server)

After debugging for 6-hours - I am giving this up :| We have a nginx+php-fpm+mysql in LAN with almost 100 wordpress (created and used by different designers/developers all working on test wordpres ...
14
votes
4answers
45k views

VirtualBox: How to set up networking so both host and guest can access internet and talk to each other

I was wondering if someone could give me a simple guide on how to set up virtual networking in VirtualBox (4.0.2) so that the following scenarios work: Both Host and Guest can access Internet Host ...
27
votes
9answers
80k views

Increase number of allowed remote desktop connections

Windows Server 2003 allows 2 non-console and one console remote desktop connections. Is there a way to increase the number of non-console sessions allowed?
23
votes
6answers
47k views

How do you increase a KVM guest's disk space?

I setup an Ubuntu guest on a CentOS KVM host with initially 6GB of disk space. How do I go about increasing the Ubuntu guest's disk space from the command line? EDIT #1: I'm using a disk image file ...
8
votes
2answers
45k views

How to test a LDAP connection from a client

How to check the LDAP connection from a client to server. I'm working on the LDAP authentication and this client desktop needs to authenticate via a LDAP server. I can SSH to the LDAP server using ...
13
votes
5answers
63k views

Need to add a “Wait” command to a Powershell script

Here is my current code: Write-output “ENTER THE FOLLOWING DETAILS - When Creating Multiple New Accounts Go to EMC hit F5(refresh) and make sure previous new account is listed before ...
28
votes
7answers
49k views

How do I check the postfix queue size?

What's the postfix equivalent to sendmail -bp?
61
27
votes
3answers
59k views

How to install/change locale on Debian?

I've written a web application for which the user interface is in Dutch. I use the system's date and time routines to format date strings in the application. However, the date strings that the system ...
22
votes
7answers
54k views

How to display certain lines from a text file in Linux?

I guess everyone knows the useful Linux cmd line utilities head and tail. Head allows you to print the first X lines of a file, tail does the same but prints the end of the file. What is a good ...
15
votes
3answers
65k views

For Loop counting from 1 to n in a windows bat script

I need to run a windows command n times within a bat script file. I know how to do this in various programming languages but cannot manage to get it right on the windows command line :-( I would ...
9
votes
3answers
43k views

How to check my PHP and MySQL version on Ubuntu VPS?

HI I am going to install MyBB but I am not sure whether I have installed the correct version of PHP and MySQL. PHP version 5.1.0 or above with XML Extension installed MySQL version 4.0 or ...
26
votes
5answers
70k views

Why do we ping the IP 4.2.2.2 to test connectivity?

For as long as I can remember, I've always used the IP 4.2.2.2 when testing network connectivity using ping. What is significant about this IP, and when did this practice start?
41
votes
7answers
48k views

mysqldump to a tar.gz

Usually after dumping a MySQL database with mysqldump command I immediately tar/gzip the resultant file. I'm looking for a way to do this in one command: So from this: mysqldump dbname -u root -p ...
0
votes
4answers
15k views

Fix/Bypass “Cannot connect to the real website-blocked” error in Google Chrome with OpenDNS blocking

I have a large problem with Chrome in my organisation. I use DNS to manage web site blocking, for sites which are not appropriate and are potentially a risk to the organisation where I do this. I ...
17
votes
4answers
26k views

hosts file ignored, how to troubleshoot?

The hosts file on Windows computers is used to bind certain name strings to specific IP addresses to override other name resolution methods. Often, one decides to change the hosts file, and discovers ...
44
votes
5answers
69k views

How to start/stop/restart launchd services from the command line?

How do I restart, say for example my httpd or afpd, running any Mac OS X >= 10.5 (Leopard-), without having to use the GUI and go to System Preferences -> Sharing and unchecking/checking "Web ...
11
votes
6answers
27k views

CentOS 6 + LDAP + NFS. File ownership is stuck on “nobody”

I've been trying to get LDAP authentication and NFS exported home directories on CentOS 6 working for a few days now. I've gotten to the point that I can now login to the client machine using the ...
10
votes
7answers
70k views

Problem adding Windows 7 64-bit print drivers to a 32-bit Windows 2003 print server

I have installed the final RTM version of Windows 7 Professional 64-bit on a test system before we begin the rollout in our company. I'm having problems connecting to several HP printers that we have ...
11
votes
1answer
59k views

Where/how does Windows store the data in the event logs?

We run some financial systems that log error messages to the system logs. I need to find out if we can clean these error messages from a PCI DSS point of view. I am specificaly interested in the ...
23
votes
5answers
73k views

What is a system state backup for?

The windows backup utility comes with an option to backup the system-state. What is this for? Has it a real utility? Can I recover that windows on another machine?
5
votes
2answers
62k views

Where can I download the latest 64-bit edition of Sonicwall SSL-VPN NetExtender for Windows 7?

Does anyone know where to download the latest edition of the 64-bit version of SonicWall SSL-VPN NetExtender for Windows 7?
16
votes
4answers
58k views

connect() failed (111: Connection refused) while connecting to upstream

I'm experiencing 502 gateway errors when accessing a PHP file in a directory (http://domain.com/dev/index.php), the logs simply says this: 2011/09/30 23:47:54 [error] 31160#0: *35 connect() failed ...
8
votes
9answers
55k views

psexec: “Access is Denied”?

Inspired by my previous question here, I've been experimenting with PSExec. The goal is to trip off some fairly simple scripts / programs on one WindowsXP machine from another, and as PowerShell 2 ...
4
votes
8answers
104k views

How do I remove Windows Update uninstall files on Windows Server 2008?

I'm running Windows Server 2008 Standard running in VMware. It has 2 disks: system disk: 16 GB data disk: 500 MB I installed Visual Studio 2008 SP1 + MSDN and some small tools and ...
8
votes
5answers
94k views

Reverse DNS - how to correctly configure for SMTP delivery

I started a new service and we need to send emails to our customers (new account confirms, etc). My server is known as prod01.bidrodeo.com and resolves to 97.107.134.38 . For reverse DNS, ...
36
votes
7answers
37k views

Is it possible to alias a hostname in Linux?

Is it possible to alias a hostname in Linux? It has been asked by jmillikin at various Ubuntu forums as follows: Is it possible to create a hostname alias? Sort of like /etc/hosts, but with other ...
52
votes
11answers
9k views

Why drop caches in Linux?

In our servers we have a habit of dropping caches at midnight. sync; echo 3 > /proc/sys/vm/drop_caches When I run the code it seems to free up lots of RAM, but do I really need to do that. ...
31
votes
6answers
47k views

How to send emails and avoid them being classified as spam

This is a canonical question about how to handle email sent from your server being misclassified as spam. For additional information you may find these similar questions helpful: Best ...
15
votes
5answers
42k views

where are the default ulimit values set? (linux, centos)

I have two CentOS (5) servers with nearly identical specs. When I login and do: ulimit -u on one machine, I get unlimited and on the other, 77824 When I run a cron like * * * * * ulimit ...
1
vote
9answers
78k views

Can ping Exchange server, can't connect Outlook to it

I can ping the Exchange server here at work, but Outlook doesn't connect to it. I've verified the server is indeed the Exchange server and I've tried using the IP instead of the server name. I am also ...