57
votes
7answers
99k views

Apache 2 startup warning: NameVirtualHost *:80 has no VirtualHosts

When my Ubuntu Apache server (Apache 2) starts up I get a warning message that reads: [warn] NameVirtualHost *:80 has no VirtualHosts However, the web server is working fine. What might I have ...
57
votes
22answers
10k views

How the heck is http://to./ a valid domain name?

Apparently it's a URL shortener. It resolves just fine in Chrome and Firefox. How is this a valid top-level domain? Update: for the people saying it's browser shenanigans, why is it that: ...
57
votes
12answers
87k views

Subversion error: (405 Method Not Allowed) in response to MKCOL

I am getting the following error while trying to commit a new directory addition. svn: Commit failed (details follow): svn: Server sent unexpected return value (405 Method Not Allowed) in response to ...
56
votes
6answers
462k views

How to determine the hostname from an IP address in a Windows network?

My LAN has 50 Windows hosts. At the Windows command line I try ping to get the IP address of a running Windows machine. The question is how to get hostname of a specific IP address in the same ...
56
votes
4answers
22k views

Where does email sent to *@example.com go? [closed]

So I've wondered this for a long time. Where does email sent to *@example.com go? If I accidentally sent sensitive information to *@example.com would some evil person (potentially at the IANA) be ...
56
votes
9answers
44k views

Is it possible to detach a process from its terminal? (Or, “I should have used screen!”) [duplicate]

Possible Duplicate: Can I nohup/screen an already-started process? On Unix (specifically, Linux), I've started a job in a regular ssh->bash session. I'd like to leave work soon, but I now ...
56
votes
22answers
20k views

rm on a directory with millions of files

Background: physical server, about two years old, 7200-RPM SATA drives connected to a 3Ware RAID card, ext3 FS mounted noatime and data=ordered, not under crazy load, kernel 2.6.18-92.1.22.el5, uptime ...
56
votes
7answers
6k views

What are the drawbacks of running a database inside a virtual machine? How do I overcome them? [closed]

Running anything inside a virtual machine will have some level of performance hit, but how much does it really impact the performance of a database system? I found this academic reference paper with ...
55
votes
17answers
24k views

Switching to IPv6 implies dropping NAT. Is that a good thing?

This is a Canonical Question about IPv6 and NAT Related: How does IPv6 subnetting work and how does it differ from IPv4 subnetting? How can I 'dip my toes' into dynamic IPv6 ...
55
votes
11answers
12k 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. ...
55
votes
7answers
15k views

How to mount a VirtualBox shared folder?

What is the procedure for mounting a VirtualBox shared folder in Linux? I tried variations of the following mount command but I keep getting protocol error or other mount errors. sudo mount -t ...
55
votes
9answers
62k views

How can I export the privileges from MySQL and then import to a new server?

I know how to export/import the databases using mysqldump & that's fine but how do I get the privileges into the new server. For extra points, there are a couple of existing databases on the new ...
55
votes
10answers
4k views

How to extinguish a small fire in a server rack to minimize damage to surrounding equipment?

Suppose I have a rack with several servers and other stuff. One of servers overheats severely and either starts smoking or catches fire while there's a serviceman nearby. If anything similar happens ...
55
votes
3answers
67k views

How to add dependency on a Windows Service AFTER the service is installed

I have a Windows Service that makes use of a SQL Server database. I don't have control over the installation of the service, but would like to add a dependency on the service to ensure that it starts ...
55
votes
5answers
128k views

How to make Windows 7 USB flash install media from Linux?

I have: ISO image of Windows 7 install media 4 GB USB flash drive no DVD drive Linux installed
55
votes
2answers
4k views

How should an IT department choose a standard Linux distribution?

There is a lot of community feeling about what Linux distributions are appropriate for production server environments and which aren't, however, a lot of this feeling seems religiously based, and ...
55
votes
20answers
23k views

Should we host our own nameservers?

I currently have my ISP providing DNS for my domain, but they impose limitations on adding records. Therefore, I am thinking about running my own DNS. Do you prefer to host your own DNS, or is it ...
55
votes
2answers
42k views

How do VLANs work?

What are VLANs? What problems do they solve? I'm helping a friend learn basic networking, as he's just become the sole sysadmin at a small company. I've been pointing him at various questions/answers ...
55
votes
11answers
117k views

How do I find if there is a rogue DHCP server on my Network?

What's the best approach towards determining if I have a rogue DHCP server inside my network? I'm wondering how most admins approach these kinds of problems. I found "DHCP Probe" ...
55
votes
8answers
110k views

What limits the maximum number of connections on a Linux server?

What kernel parameter or other settings control the maximum number of TCP sockets that can be open on a Linux server? What are the tradeoffs of allowing more connections? I noticed while load testing ...
54
votes
6answers
14k views

Why use Chef/Puppet over shell scripts?

New to Puppet and Chef tools. Seems like the job that they are doing can be done with shell scripting. Maybe it was done in shell scripts until these came along. I would agree they are more readable. ...
54
votes
5answers
61k views

Clean way to write complex multi-line string to a variable

I need to write some complex xml to a variable inside a bash script. The xml needs to be readable inside the bash script as this is where the xml fragment will live, it's not being read from another ...
54
votes
4answers
24k views

How do I edit git's history to correct an incorrect email address/name [closed]

When I started using git I just did a git init and started calling add and commit. Now I am starting to pay attention and I can see that my commits are showing up as cowens@localmachine, rather than ...
54
votes
6answers
12k views

Heartbleed: are services other than HTTPS affected?

The OpenSSL 'heartbleed' vulnerability (CVE-2014-0160) affects webservers serving HTTPS. Other services also use OpenSSL. Are these services also vulnerable to heartbleed-like data leakage? I'm ...
54
votes
14answers
2k views

Is UPS worthwhile for non-production equipment? [closed]

Over the years, I've had to throw away a quite a few bits of computing equipment (and the like): Several ADSL routers with odd symptoms (losing wireless connections, losing wired connections, DHCP ...
54
votes
10answers
16k views

Unique Features of bash compared to zsh

I have been a zsh user for quite some time (before that tcsh and before that csh). I am quite happy with it, but was wondering if there are any compelling features of bash that do not exist in zsh. ...
54
votes
13answers
80k views

Windows 2008: WinSXS directory growing uncontrollably, blocking server

I run a (remotely hosted) virtual Server with Windows 2008 Server for a client. Initially, it had 10 GB of space. During the course of a few weeks - during which nothing was done on the machine ...
54
votes
4answers
21k views

How do I rename a task in Task Scheduled on Windows Server 2008 R2

I have some tasks in the Task Scheduler on Windows 2008 R2. I created them as the admin and I'm logged in as the admin. I have no easy way to rename the tasks. The only way I can is to export the task ...
54
votes
3answers
12k views

Can I create a top level TLD? (.michael for instance)

It appears that ICANN is allowing the creation of top level domains. Instead of 'registering' a domain, you would essentially be signing up to be a registrar (you'd be giving out registrations on ...
53
votes
15answers
8k views

Are IP addresses “trivial to forge”?

I was reading through some of the notes on Google's new public DNS service: Performance Benefits Security Benefits I noticed under the security section this paragraph: Until a standard ...
53
votes
6answers
17k views

Fighting Spam - What can I do as an: Email Administrator, Domain Owner, or User?

This is a Canonical Question about Fighting Spam. Also related: How to stop people from using my domain to send spam? What are SPF records, and how do I configure them? There are ...
53
votes
11answers
80k views

IIS 7.5 (Windows 7) - HTTP Error 401.3 - Unauthorized

I'm trying to test my ASP.Net website on localhost and I'm getting this error: HTTP Error 401.3 - Unauthorized You do not have permission to view this directory or page because of the access control ...
53
votes
5answers
102k views

Find name of Active Directory domain controller

How can I find out the name/IP address of the AD domain controller on my network?
53
votes
20answers
16k views

How do you document a network?

I'm not sure how to ask this question, since I'm not in the field. Say you're a network admin and you leave your job. How does the new guy know where to start?
53
votes
3answers
21k views

What is a glue record?

This is a Canonical Question about DNS glue records. What exactly (but briefly) is a DNS glue record? Why are they needed and how do they work?
53
votes
1answer
56k views

InnoDB: Error: log file ./ib_logfile0 is of different size

I just added the following lines in /etc/mysql/my.cnf after I converted one database to use InnoDB engine. innodb_buffer_pool_size = 2560M innodb_log_file_size = 256M innodb_log_buffer_size = 8M ...
53
votes
10answers
20k views

How does a team of Systems Administrators share passwords securely?

What are best practices for sharing hundreds of passwords among a few people? These passwords protect mission critical data, and cannot ever be visible beyond a small team.
52
votes
6answers
4k views

Why can't MX records point to an IP address?

I understand you should not point a MX record at an IP address directly, but should instead point it to an A record, which, in turns, points to the IP address of your mail server. But, in principle, ...
52
votes
2answers
60k views

SFTP logging: is there a way?

I'm wondering if there is a way to log commands received by the server. It can be all SSH commands, as long as it includes information on commands related to file transfer. I'm having issues with an ...
52
votes
9answers
61k views

Finding out what user Apache is running as?

I want to secure a file upload directory on my server as described beautifully here, but I have one problem before I can follow these instructions. I don't know what user Apache is running as. I've ...
52
votes
9answers
70k views

What's the best way to move c:\users to d:\users under vista/W7 [closed]

I just installed Windows 7 RC1 and want to move c:\users to d:\users. What's the best way to do this? Due to the fact that Windows 7 creates a reserved partition that is mounted as C: in the ...
52
votes
2answers
311k views

How to check if a port is blocked on a Windows machine?

On the Windows platform, what native options to I have to check if a port (3306, for example) on my local machine (as in localhost), is being blocked?
52
votes
19answers
7k views

Best Practise and Solutions for Sharing Passwords [closed]

We have various passwords that need to be known to more than one person in our company. For example, the admin password to our internet routers, the password for our web-host, and also a few "non-IT" ...
52
votes
1answer
26k views

How do I change my private key passphrase?

I have an existing public/private key pair, the private key is password protected, the encryption may be either RSA or DSA. These keys are the kind you generate with ssh-keygen and generally store ...
52
votes
2answers
10k views

Why is it so difficult to upgrade between major versions of Red Hat and CentOS?

"Can we upgrade our existing production EL5 servers to EL6?" A simple-sounding request from two customers with completely different environments prompted my usual best-practices answer of "yes, but ...
51
votes
10answers
14k views

How to [politely?] tell software vendor they don't know what they're talking about

Not a technical question, but a valid one nonetheless. Scenario: HP ProLiant DL380 Gen 8 with 2 x 8-core Xeon E5-2667 CPUs and 256GB RAM running ESXi 5.5. Eight VMs for a given vendor's system. ...
51
votes
23answers
75k views

How to copy a large number of files quickly between two servers

I need to transfer a huge amount of mp3s between two serves (Ubuntu). By huge I mean about a million files which are on average 300K. I tried with scp but it would have taken about a week. (about 500 ...
51
votes
17answers
10k views

Do you skip a rack unit between servers?

It seems like there's a lot of disagreement in mindsets when it comes to installing rackmount servers. There have been threads discussing cable arms and other rackmount accessories, but I'm curious: ...
51
votes
2answers
3k views

Mysterious visitor to hidden PHP page

On my website, I have a "hidden" page that displays a list of the most recent visitors. There exist no links at all to this single PHP page, and, theoretically, only I know of its existence. I check ...
51
votes
8answers
2k views

What are the advantages of tape drives?

IBM still develop and sell tape drives today. The capacity of them seems to be on a par with today's hard drives, but the search time and transfer rate are both significantly lower than that of hard ...

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