58
votes
15answers
8k views

Hundreds of failed ssh logins

Every night I get hundreds, sometimes thousands, of failed ssh logins on my RedHat 4 server. For firewall reasons from remote sites, I need to run on the standard port. Is there anything I should be ...
58
votes
11answers
58k views

apache2: Could not reliably determine the server's fully qualified domain name, using 127.0.1.1 for ServerName

I keep getting this warning when I (re)start Apache. * Restarting web server apache2 apache2: Could not reliably determine the server's fully qualified domain name, using 127.0.1.1 for ...
58
votes
4answers
30k 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 ...
58
votes
9answers
48k views

Dump Microsoft SQL Server database to an SQL script

Is there any way to export a Microsoft SQL Server database to an sql script? I'm looking for something which behaves similarly to mysqldump, taking a database name, and producing a single script ...
57
votes
12answers
50k views

In my /etc/hosts/ file on Linux/OSX how do I do a wildcard subdomain?

I need to test sub-domains on my localhost. How can I effectively have this result of adding *.localhost.com to m /etc/hosts/ file? If it's not possible, how do I work around this problem? I need ...
57
votes
9answers
104k views

How to refresh hosts file without rebooting

On Windows, how do you refresh the hosts file without rebooting?
57
votes
6answers
36k views

How to force or redirect to SSL in nginx?

I have a signup page on a subdomain like: https://signup.mysite.com It should only be accessible via HTTPS but I'm worried people might somehow stumble upon it via HTTP and get a 404. My ...
57
votes
7answers
92k 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
2answers
64k 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 ...
56
votes
6answers
2k views

Choosing between meaningful and meaningless hostnames

Assume an environment with a puppet-managed cluster of different servers - various hardware, software, operating systems, virtual/dedicated, etc. Would you choose meaningful hostnames ...
56
votes
7answers
4k views

DNS failing to propagate worldwide

I haven't changed anything related to the DNS entry for serverfault.com, but some users were reporting today that the serverfault.com DNS fails to resolve for them. I ran a justping query and I can ...
56
votes
7answers
46k views

How can I run Debian stable but install some packages from testing?

Say you're running a server and you don't want to upgrade to Testing (Squeeze) from Stable (Lenny) to just install a required package or two. What's the best way of installing only certain packages ...
56
votes
8answers
144k views

Can't seem to disable Java Automatic Update

I'm just tweaking out my new Windows 7 laptop and wanted to disable the automatic Java updating (and thus kill the silly jusched.exe background process), but I can't seem to get it to actually turn it ...
56
votes
5answers
7k views

Tips for Securing a LAMP Server

This is a Canonical Question about Securing a LAMP stack What are the absolute guidelines for securing a LAMP server?
56
votes
8answers
64k views

how to set global PATH on OS X?

I'd like to append to the global PATH variable on OS X so that all user shells and GUI applications get the same PATH environment. I know I can append to the path in shell startup scripts, but those ...
56
votes
13answers
25k views

What steps do you take to secure a Debian server?

I am installing a Debian server which is connected directly to the Internet. Obviously I want to make it as secure as possible. I would like you guys/gals to add your ideas to secure it and what ...
55
votes
13answers
23k views

How Often Do Windows Servers Need to be Restarted?

A little background: We have several Windows servers (2003, 2008) for our department. We're a division of IT so we manage our own servers. Of the four of us here I'm the only one with a slight amount ...
55
votes
6answers
73k views

How can I find out what AD groups I'm a member of?

I'm running a Windows XP desktop in a corporate environment. How can I find out what AD groups I belong to?
55
votes
22answers
9k 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: ...
55
votes
13answers
10k views

Are networks now faster than disks?

This is a software design question I used to work on the following rule for speed cache memory > memory > disk > network With each step being 5-10 times the previous step (e.g. cache ...
55
votes
9answers
77k 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 ...
54
votes
5answers
385k views

What port does SFTP use?

Does SFTP use port 21 or port 22?
54
votes
6answers
60k views

How to forcibly close a socket in TIME_WAIT?

I run a particular program on linux which sometimes crashes. If you open it quickly after that, it listens on socket 49201 instead of 49200 as it did the first time. netstat reveals that 49200 is in ...
54
votes
8answers
144k views

What's the command-line utility in Windows to do a reverse DNS look-up?

Is there a built-in command line tool that will do reverse DNS look-ups in Windows? I.e., something like <toolname> w.x.y.z => mycomputername I've tried: nslookup: seems to be forward ...
54
votes
7answers
71k views

How do I get current Unix time in milliseconds using bash?

How do I get the current Unix time in milliseconds (i.e number of milliseconds since Unix epoch January 1 1970)?
54
votes
7answers
4k 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 ...
54
votes
8answers
59k views

Dealing with HTTP w00tw00t attacks

I have a server with apache and I recently installed mod_security2 because I get attacked a lot by this: My apache version is apache v2.2.3 and I use mod_security2.c This were the entries from the ...
53
votes
10answers
3k 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 ...
53
votes
10answers
38k views

memcache vs memcached?

I want to use memcached http://www.danga.com/memcached/ I have installed it through yum install memcached But now I need to connect to PHP, and there is an extension named memcache and one named ...
53
votes
8answers
19k views

sudo su - username while keeping ssh key forwarding

If I have a server A into which I can login with my ssh key and I have the ability to "sudo su - otheruser", I lose key forwarding, because the env variables are removed and the socket is only ...
53
votes
10answers
15k 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. ...
53
votes
1answer
638 views

Fibre channel long distance woes

I need a fresh pair of eyes. We're using a 15km fibre optic line across which fibrechannel and 10GbE is multiplexed (passive optical CWDM). For FC we have long distance lasers suitable up to 40km ...
52
votes
13answers
21k views

Why is RAID not a backup?

When someone mentions RAID in a conversation about backups, invariably someone declares that "RAID is not a backup". Sure, for striping, that's true. But whats the difference between redundancy and a ...
52
votes
5answers
13k views

Active Directory explained

If you had to explain Active Directory to someone how would you explain it?
52
votes
24answers
12k views

Which websites should a system administrator read? [closed]

I try to religiously follow planet sysadmin as well as IBM developerworks. Which ones do you read and advise to other system administrators?
52
votes
6answers
10k 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 ...
52
votes
3answers
8k 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 ...
50
votes
4answers
55k views

Can scp copy directories?

Now I can only copy a single tar file,how can I copy directories recursively with scp?
50
votes
6answers
13k views

Puppet vs Chef, pro and contra from users and use cases [closed]

I already googled and read the "to-puppet-or-to-chef-that-is-the-question" article. I'm interested in use cases, real world implementations in which people had choosen one or the other on real ...
50
votes
3answers
47k views

how to download the ssl certificate from a website?

I want to download the ssl certificate from, say https://www.google.com, using wget or any other commands. Any unix command line? wget or openssl?
50
votes
4answers
49k views

What's the difference between ip address 0.0.0.0 and 127.0.0.1?

I do know that 127.0.0.1 ~ 127.255.255.254 are the loopback IP addresses for most modern operating systems and we could use these IP addresses to refer to our own computer. But what's 0.0.0.0? It ...
50
votes
9answers
67k views

How do you add a Windows environment variable without rebooting?

This is probably an easy answer, but I have never been able to find it by googling. I simply would like to add an Environment variable to a Windows machine (desktop or server) and be able to use it ...
50
votes
18answers
13k 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?
50
votes
9answers
11k views

Company Password Management [closed]

The topic of personal password management has been covered in great detail time after time. This question is aimed at the business or organization that needs to keep track of many unique passwords for ...
50
votes
13answers
72k 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 ...
49
votes
13answers
50k views

How to reconnect to a disconnected ssh session

Is there a way to connect to an ssh session that was disconnected? We are having problems with our network connection to a remote site that we are working on separately; however, in the mean time we ...
49
votes
5answers
2k views

How should an IT department choose a Linux distribution: Technical reasons

There is a lot of community feeling about what Linux distributions are appropriate for production server environments and what aren't. Some of this is based on the availability of commercial support. ...
49
votes
20answers
18k views

Hosting your own DNS

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 ...
49
votes
3answers
34k 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. ...
48
votes
9answers
33k 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 ...

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