16
votes
3answers
23k views

How to configure postfix to pipe all incoming email to a script?

Using postfix, I'd like all incoming mail, to any address (including those that don't map to local users) to be piped to a script. I've tried configuring mailbox_command in /etc/postfix/main.cf: ...
39
votes
5answers
72k views

What is the difference between SAN, NAS and DAS?

What is the difference between SAN, NAS and DAS?
18
votes
10answers
3k views

Network Traffic Monitoring

What is the best tool to monitor/analyze network traffic on an entire network (several subnets)? I'm looking for something that will help me toubleshoot bandwidth problems when, for instance, users ...
10
votes
3answers
2k views

LAMP Server Performance Tips [closed]

What performance tips can be offered to someone running a LAMP server? In the instance that something is Distribution specific, I'm targeting Debian.
34
votes
6answers
13k views

Debugger for Iptables

I'm looking for an easy way to follow a packet through the iptables rules. This is not so much about logging, because I don't want to log all traffic (and I only want to have LOG targets for very few ...
43
votes
1answer
12k views

Why are my XFS filesystems suddenly consuming more space and full of sparse files?

I've run XFS filesystems as data/growth partitions for nearly 10 years across various Linux servers. I've noticed a strange phenomenon with recent CentOS/RHEL servers running version 6.2+. Stable ...
32
votes
3answers
34k views

iptables port redirect not working for localhost

I want to redirect all traffic from port 443 to the internal port 8080. I'm using this config for iptables: iptables -t nat -I PREROUTING --source 0/0 --destination 0/0 -p tcp \ --dport 443 -...
64
votes
6answers
53k views

Is X.Y.Z.0 a valid IP address?

Are IP addresses with a 0 in the last octet valid? 10.6.43.0 In my case, I have the the following netmask 255.255.252.0 What about a 0 for the other octets?
61
votes
8answers
70k views

Is a wildcard CNAME DNS record valid?

I know it's valid to have a DNS A record that's a wildcard (e.g. *.mysite.com). Is it possible/valid/advised to have a wildcard CNAME record?
27
votes
8answers
8k views

How do you setup ssh to authenticate using keys instead of a username / password?

How do you setup ssh to authenticate a user using keys instead of a username / password?
33
votes
5answers
4k views

Smoothest workflow to handle SSH host verification errors?

This is a simple issue that we all face and probably resolve manually without giving much thought. As servers change, are re-provisioned, or IP addresses reallocated, we receive the SSH host ...
23
votes
7answers
28k views

How to workaround the NTFS Move/Copy design flaw?

As anyone that has dealt with file server permissions is aware, NTFS has an interesting design feature/flaw known as the Move/Copy problem. As explained in this MS KB article, the permissions for a ...
21
votes
6answers
6k views

Can windows domain controller be virtualized?

Just the question on the title. There is any problem? Any experience on this?
19
votes
10answers
38k views

How do I know if I am running 32 or 64-bit Linux?

what would be a command to run in different distros?
23
votes
8answers
5k views

accidently ran “chown www-data:www-data / -R” as root

i just ran this a few seconds ago, i managed to do ctrl-c as soon as i realized what i started doing. so far in the only dir its started going through is /bin im afraid to do anything else, so far ...
21
votes
6answers
36k views

Choosing local versus public domain name for Active Directory [duplicate]

What are the pros and cons of choosing a local domain name such as mycompany.local versus a publicly registered domain name such as mycompany.com (assuming that your org has registered the public name)...
18
votes
5answers
13k views

How can I chroot ssh connections?

I would like to setup a chroot jail for most (not all) users logging in though SSH. I've heard it's possible with the latest versions of openssh, but I've not been able to find out how to do it. The ...
27
votes
6answers
3k views

Linux server out of space

I have been asked this question in two consecutive interviews, but after some research and checking with various systems administrators I haven't received a good answer. I am wondering if somebody can ...
9
votes
9answers
31k views

How to repair/restore ubuntu 10.04 after 'sudo chmod / 777'

See Also: Why is “chmod -R 777 /” destructive? I changed file permissions recursively on the root directory / by executing sudo chmod -R / 777, and after that my system won't boot (...
8
votes
3answers
8k views

How to diagnose causes of oom-killer killing processes

I have a small virtual private server running CentOS and www/mail/db, which has recently had a couple of incidents where the web server and ssh became unresponsive. Looking at the logs, I saw that ...
19
votes
2answers
2k views

Do the SSH or FTP protocols tell the server to which domain I am trying to connect?

When using the ssh or ftp commands from the Bash shell, does the server that I am connecting to learn of the domain name used? I understand that the domain name is locally translated into an IP ...
9
votes
3answers
14k views

Redirect non-www requests to www on Amazon Route 53

I want to redirect all requests from example.com to www.example.com. Preferably, this should happen at DNS level. I tried using PTR records, but that simply fails, returning a 404. wwww.example.com ...
5
votes
3answers
9k views

How do I find out what is using up all the space on my / partition?

I am on a large instance on Amazon's EC2 servers. I run the df command and get: root@db:~# df -h Filesystem Size Used Avail Use% Mounted on /dev/sda1 9.9G 9.1G 284M 98% / ...
4
votes
2answers
5k views

Install Oracle Linux 6.4 on HP ProLiant DL380e Gen8 server

installation does not detect the raid 1 logical drive created from ACU. the installation shows the two 2T disks, and after the installation is complete, I can not boot up to the system. I have been ...
12
votes
2answers
1k views

How do I prevent Apache from answering requests for domains I don't host?

Someone has pointed their domain (www.bomberball.net) to the same IP as my domain (www.kapparate.com) , and Google is now showing the former when searching for Kapparate, rather than the latter. What'...
1
vote
1answer
2k views

My OpenSolaris Server hangs when writing large files after upgrading zpool

yesterday I added new harddrives(four as a raidz1 and one as hot-spare) to a opensolaris server, after extending the zpool the server hangs when writing large files but not when reading large files(...
1
vote
1answer
391 views

Lame DNS server

I'm trying to setup my BIND with a domain I own and I'm using dnssy.com and intodns.com to check if everything is ok, but I'm getting errors in both. The error says that my DNS server is "lame" (...
16
votes
4answers
13k views

How is Windows Server different from regular Windows?

I can run IIS on a normal installation, what is so different about windows server?
4
votes
1answer
2k views

How to maintain PCI compliance on a LAMP server when repositories don't keep up with versions

We run Ubuntu Lucid 10.0.4 as the foundation of our LAMP environment. We are trying to become PCI compliant so that we can pass CC info through our server. We have run some third-party scans on our ...
3
votes
4answers
968 views

ssh delay when connecting

When connecting to one specific server (running Debian Lenny) it always takes about 5 seconds before it prompts me to enter a password. After login there is no noticable delay anymore. There is also ...
3
votes
3answers
6k views

What is the memory module on a RAID card needed for?

As above, what is the reason for needing a memory module on a RAID card? The card I am looking at (HP P410) comes with either 256MB or 512MB but unsure which to get and why.
0
votes
1answer
1k views

Ubuntu 12.04 Server - MySQL keeps crashing - Possible InnoDB problems

I have been searching for a solution but nothing seems to work. I have a single Drupal 6 website up on this server. Server:Ubuntu 12.04 Apache/2.2.22 (Ubuntu) 5.3.10-1ubuntu3.8 MySQL 5.5.32 Drupal ...
461
votes
34answers
221k views

How can I sort du -h output by size

I need to get a list of human readable du output. However, du does not have a "sort by size" option, and piping to sort doesn't work with the human readable flag. For example, running: du | sort -...
53
votes
21answers
32k views

Storing a million images in the filesystem

I have a project that will generate a huge number of images. Around 1,000,000 for start. They are not large images so I will store them all on one machine at start. How do you recommended on ...
77
votes
3answers
103k 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 ...
68
votes
5answers
5k views

Choosing between meaningful and meaningless hostnames [closed]

Assume an environment with a puppet-managed cluster of different servers - various hardware, software, operating systems, virtual/dedicated, etc. Would you choose meaningful hostnames (mysqlmaster01.....
43
votes
6answers
15k views

Meaning of directories on Unix and Unix like systems

I've been using Linux for a couple of years now but I still haven't figured out what the origin or meaning of some the directory names are on Unix and Unix like systems. E.g. what does etc stand for ...
44
votes
16answers
45k views

Is Round-Robin DNS “good enough” for load balancing static content?

We have a set of shared, static content that we serve up between our websites at http://sstatic.net. Unfortunately, this content is not currently load balanced at all -- it's served from a single ...
32
votes
5answers
22k views

Why Does hotmail still reject my emails?

I have a very strange problem with my emails being marked as spam by hotmail. I just have configured Postfix + Dovecot on my server and all works perfectly. I can Send/Receive emails. I only have ...
26
votes
2answers
72k views

How does ServerName and ServerAlias work?

It's the following part of a virtual host config that I need further clarification on: <VirtualHost *:80> # Admin email, Server Name (domain name), and any aliases ServerAdmin example@...
73
votes
14answers
5k views

What's wrong with always being root?

I have a feeling this is a stupid question, but this is something I've wondered for awhile. I have a VPS and this is my first big linux venture. I am the only person who has access to it. My question ...
11
votes
2answers
24k views

Load balancing & NAT-ing multiple ISP connections on Linux

I have two internet connections from two different ISPs and I need to balance the traffic originating to and from my network between the two ISPs. I am using Debian GNU/Linux. My set-up is like this -...
38
votes
6answers
11k views

If a Windows shop moves “everything” to the cloud, does it still need Active Directory?

Taking a spin off of this question: Do I really need MS Active Directory? in a new direction for 2014. Taking into account a basic Windows infrastructure: domain controllers Exchange 2007/2010/2013 ...
19
votes
5answers
87k views

Huge amount of TIME_WAIT connections says netstat

Okay, this is creeping me out - I see about 1500-2500 of these: root@wherever:# netstat Proto Recv-Q Send-Q Local Address Foreign Address State tcp 0 0 localhost:...
42
votes
12answers
2k views

Sell partitioning to me

I have often wondered why there is such a passion for partitioning drives, especially on Unixy OSes (/usr, /var, et al). This does not seem to be a common theme with Windows installations. It seems ...
29
votes
2answers
11k views

SSL password on apache2 restart

I setup wildcard SSL certificate from Godaddy on Apache2. Whenever the server restarts it asks for the passphrase for the SSL certificate's private key. What's the best way to remove this obstacle ...
47
votes
2answers
13k views

Why does Heroku warn against “naked” domain names?

I ran across this page in the Heroku docs... Naked domains, also called bare or apex domains, are configured in DNS via A-records and have serious availability implications when used in highly ...
32
votes
8answers
38k views

Private IP address in public DNS

We have an SMTP only mail server behind a firewall which will have a public A record of mail.. The only way to access this mail server is from another server behind the same firewall. We do not run ...
5
votes
3answers
11k views

How to resize the disk of a Fedora guest VM in VMWare ESXi

How do I resize (specifically increase) the disk size of a Fedora guest VM running under VMWare ESXi 4.1? I have a Fedora 16 VM with an lvm2 formatted disk, and I've increased its disk size using the ...
64
votes
11answers
21k 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. Isn'...

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