Greatest Hits

48
votes
3answers
34k views

Why is my crontab not working, and how can I troubleshoot it?

This is a Canonical Question about using cron & crontab. The answer for 'Why is my crontab not working, and how can I troubleshoot it?' can be seen below. This addresses the cron system with ...
44
15
votes
11answers
98k views

Best way to find the computer a user last logged on from?

I am hoping that somewhere in Active Directory the "last logged on from [computer]" is written/stored, or there is a log I can parse out? The purpose of wanting to know the last PC logged on from is ...
11
votes
4answers
57k views

Which ports do I need to open in the firewall to use NFS?

I'm running Ubuntu 11.10 - setting up NFS to share a directory among many other servers. Which ports are required to be opened on the firewall?
32
votes
4answers
108k views

Is it possible to change an “Unidentified Network” into a “Home” or “Work” network on Windows 7

I have a problem with Windows 7 RC (7100). I frequently use a crossover network cable on WinXP with static IP addresses to connect to various industrial devices (e.g. robots, pumps, valves or even ...
24
votes
4answers
6k views

Does a company have implied right to crawl my website?

I have found out that McAfee SiteAdvisor has reported my website as "may be having security issues". I care little about whatever McAfee thinks of my website (I can secure it myself and if not, ...
5
votes
6answers
61k views

How do I completely remove MySQL from a linux installation?

I was surprised to find that one of my privileged users installed MySQL on a linux box. The server (mysqld) is running and doing nothing. My skills are all in Oracle, so I am unfamiliar with how to ...
54
votes
2answers
43k views

how to disable SSH login with password for some users?

On Linux (Debian Squeeze) I would like to disable SSH login using password to some users (selected group or all users except root). But I do not want to disable login using certificate for them. ...
4
votes
3answers
31k views

What is a Cisco BVI interface? What is it used for?

I have been Google'd and searched for the answer to these questions, but I cannot find a simple answer. So my questions are about BVI interfaces. What are they? Why do you use them? In what scenario ...
14
votes
3answers
34k views

MySQL lowering wait_timeout value to lower number of open connections

I run a rather busy site, and during peek hours I see over 10.000 open connections to my database server on my webserver when a run a netstat command. 99% of the connections are in the TIME_WAIT ...
5
votes
3answers
71k views

How to completely remove MS SQL Server 2008 R2 x64 which was uninstalled incorrectly?

On my Windows 7 Ultimate x64 I can't do anything with the existing instance of MS SQL Server 2008 R2. It was my mistake to uninstall some components related to SQL Server before running the main ...
71
votes
6answers
62k views

Setting the hostname: FQDN or short name?

I've noticed that the "preferred" method of setting the system hostname is fundamentally different between Red Hat/CentOS and Debian/Ubuntu systems. CentOS documentation and the RHEL deployment guide ...
13
votes
9answers
33k views

Linux (mv or cp) specific files from a text list of files?

I have a directory of many files, something like 50,000 pdf's and other files on a server. I need to move specific ones to another directory. I can generate a list of the files that need to be moved ...
23
votes
6answers
82k views

add new user with root access in Linux

I want to add new user and have/grant that new user to have all the root access, how can I do that ? I did sudo adduser --system testuser but this is not working as I expected. Thanks for help.
6
votes
7answers
55k views

How do I permanently change the hostname on Solaris 10?

I want to permanently change the hostname on a Solaris box. How do I do that?
64
6
votes
8answers
42k views

Exchange 2010 and Outlook 2010 requesting password every time it starts

I have one Exchange 2010 server which is fully updated, the clients are running Outlook 2010 but some users are getting a prompt for credentials every time they open Outlook. I have checked for ...
32
votes
4answers
68k views

How do I grant start/stop/restart permissions on a service to an arbitrary user or group on a non-domain-member server?

We have a suite of Windows Services running on our servers which perform a bunch of automated tasks independently of one another, with the exception of one service which looks after the other ...
0
votes
4answers
13k 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 ...
9
votes
1answer
58k views

What is a SQL Server instance?

When I install SQL Server 2008 Express in prompts me to create an instance and aborts if I don't. Then I see that information in an entry in Sql Server Configuration Manager on SQL Server Services. ...
11
votes
11answers
64k views

How do I find out which devices are on a network?

How do I scan a network to find out which devices are on it? (I'd be happy with a list of MAC addresses and IPs.) For example, lets say I'm at work and want to be sure that there are no unknown ...
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 ...
59
votes
2answers
80k views

How to Configure Windows Machine to Allow File Sharing with DNS Alias

What process is necessary to configure a Windows environement to allow me to use DNS CNAME to reference servers? I want to do this so that I can name my servers something like SRV001, but still have ...
113
votes
3answers
39k views

What is the difference between double and single square brackets in bash?

I just wondered what exactly the difference between [[ $STRING != foo ]] and [ $STRING != foo ] is, apart from that the latter is posix-compliant, found in sh and the former is an extension ...
75
votes
4answers
41k views

Moving an already-running process to Screen

My office job routinely sees me connected to a Linux box via VNC. Sometimes I start a remote job on the console, and realize later that it runs much longer than expected. (Should have started that ...
31
votes
8answers
40k views

How to change sshd port on Mac OS X?

I want to change sshd's port on Mac OS X from default 22 to 32, but editing /etc/sshd_config seems does not work. How can I change it?
29
votes
2answers
75k views

How to check sshd log?

I have Ubuntu 9.10 installed with sshd and i can successfully connect to it using login and password. I have configured an RSA key login and now have "Server refused our key" as expected. Ok, now i ...
41
14
votes
5answers
52k views

What is the value of JAVA_HOME for CentOS?

I have install java through yum on CentOS, however another java programme needs to know what the JAVA_HOME environmental variable is. I know all about setting environmental variables, but what do I ...
5
votes
11answers
62k views

Windows command prompt: how to get the count of all files in current directory?

What command would you use in cmd.exe to find the number of files in the current directory? Is there a powershell option here? Update: I was hoping to avoid dir, as I know there are 10,000+ files in ...
13
votes
4answers
28k views

Unknown/unsupported storage engine: InnoDB | MySQL Ubuntu

I recently upgraded from the previous LTS Ubuntu to Precise and now mysql refuses to start. It complains of the following when I attempt to start it: ╰$ sudo service mysql restart stop: Unknown ...
10
votes
3answers
18k views

How to Restart explorer.exe Remotely?

I'm having big troubles with a remote server that for some reason explorer.exe crashed and, although I didn't lose remote desktop connectivity, I can't do anything. Is there a way of restarting ...
6
votes
7answers
42k views

What is an edge server / router / device?

What is an edge server? We see some references to them, but we never see a definition.
68
13
votes
7answers
47k 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 ...
21
votes
6answers
47k views

what are named and default instance?

what are named and default instance? what is the difference between them? why they are used?
13
votes
4answers
37k views

How to configure vsftpd to work with passive mode

Whenever I install vsftpd on centos, I only setup the jail environment for the users and rest is default configuration of vsftpd. I create user and try to connect with filezila ftp client but I could ...
19
votes
5answers
73k 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 ...
2
votes
1answer
16k views

How to disable user's password via puppet securely?

I have my SSH servers setup to use only Public Key authentication with password authentication disabled. When adding users through puppet I would like to disable user passwords. So far I have came ...
14
votes
4answers
62k 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 ...
0
votes
2answers
12k views

phpmyadmin “Forbidden: You don't have permission to access /phpmyadmin on this server.”

I need to modify the file /etc/httpd/conf.d/phpMyAdmin.conf in order to allow remote users (not only localhost) to login # phpMyAdmin - Web based MySQL browser written in php # # Allows only ...
175
votes
13answers
65k 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 ...
25
votes
9answers
42k views

How do I get apt-get to ignore some dependencies?

How do I make apt-get ignore some dependencies? For example, I wanted to install mailx so I can use it to send email from cron scripts/report-generating tools. However, installing mailx also installs ...
27
votes
9answers
79k 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?
11
votes
4answers
58k 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 ...
14
votes
8answers
58k views

How to make a bootable USB drive out of a bootable DVD or CD

Is there a "universal" way of how you can make a bootable USB drive out of a bootable dvd or cd? What makes a USB drive bootable? What makes a dvd and cd bootable? For example there is a program ...
29
votes
7answers
67k views

Why do I get sqlite error, “unable to open database file”?

Using my Django app, I'm able to read from the database just fine. When the application didn't have permission to access the file, it gave me this error: attempt to write a readonly database ...
14
votes
4answers
58k 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 ...
25
votes
4answers
53k 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 ...
51
votes
10answers
8k 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. ...
21
votes
10answers
63k 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?
10
votes
6answers
32k views

How to completely remove MySQL from Windows?

(I realize there are similarly-titled questions, but this one is really 'how do I reset the password', and this one doesn't specify an OS and has only gotten Linux-oriented answers.) On Windows XP, I ...
69
14
votes
2answers
27k views

How to make wireshark filter POST-requests only?

How to make wireshark filter POST-requests only?
62
23
votes
1answer
41k 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 ...
61