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1500 questions
111
votes
6 answers
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 so many techniques and so much to know about fighting SPAM.…
Chris S
- 78,185
111
votes
9 answers
How to stop people from using my domain to send spam?
I receive Mailer Daemon messages saying certain emails fail. My domain is itaccess.org which is administered by Google apps. Is there any way I can identify who is sending emails from my domain, and how they are doing it without me creating an…
Billy Moon
- 1,437
111
votes
9 answers
Allow SFTP but disallow SSH?
I'm starting a very little hosting company for a few friends and little clients, nothing big.
I want to give my "clients" the right to manage their files on the server. I hate FTP as it is not secure and it's in my opinion obsolete.
So I'd like to…
Tommy B.
- 1,433
- 2
- 14
- 14
111
votes
6 answers
How to force nginx to resolve DNS (of a dynamic hostname) everytime when doing proxy_pass?
I am using nginx/0.7.68, running on CentOS, with the following configuration:
server {
listen 80;
server_name ***;
index index.html index.htm index.php default.html default.htm default.php;
location / {
root …
xiamx
- 1,302
111
votes
9 answers
Can I send some text to the STDIN of an active process running in a screen session?
I have a long-running server process inside a screen session on my Linux server. It's a bit unstable (and sadly not my software so I can't fix that!), so I want to script a nightly restart of the process to help stability. The only way to make it do…
Richard Gaywood
110
votes
3 answers
Is there a way to see the execution tree of systemd?
What I mean under the question is: is there a way to dump the ordered list (like pstree does for processes) to see how systemd executed the supplied set of units, i.e. the tree after the dependencies were resolved and jobs were queued for the…
galaxy
- 2,157
110
votes
7 answers
How can the little guys effectively learn and use Puppet?
Six months ago, in our not-for-profit project we decided to start migrating our system management to a Puppet-controlled environment because we are expecting our number of servers to grow substantially between now and a year from now.
Since the…
drumfire
- 1,709
110
votes
10 answers
How do I update a CentOS server's time from an authoritative time server?
I have CentOS machine and each time I've noticed that the server loses correct time after a while. It is usually behind by several minutes after time passes from having manually set the correct time. Is there a mechanism whereby I can update the…
user111196
- 1,257
110
votes
8 answers
How can a single disk in a hardware SATA RAID-10 array bring the entire array to a screeching halt?
Prelude:
I'm a code-monkey that's increasingly taken on SysAdmin duties for my small company. My code is our product, and increasingly we provide the same app as SaaS.
About 18 months ago I moved our servers from a premium hosting centric vendor to…
Stu Thompson
- 3,379
110
votes
20 answers
Why should I firewall servers?
PLEASE NOTE: I'm not interested in making this into a flame war! I understand that many people have strongly-held beliefs about this subject, in no small part because they've put a lot of effort into their firewalling solutions, and also because…
Ernie
- 5,352
110
votes
10 answers
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 command to print the middle of a file? something like…
Boaz
- 2,259
110
votes
5 answers
Multiple SSL domains on the same IP address and same port?
This is a Canonical Question about Hosting multiple SSL websites on the same IP.
I was under the impression that each SSL Certificate required it's own unique IP Address/Port combination. But the answer to a previous question I posted is at odds…
learningtech
- 7,445
- 23
- 64
- 88
110
votes
1 answer
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
innodb_flush_log_at_trx_commit =…
jack
- 1,725
109
votes
8 answers
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 hostnames rather than IP addresses. So that with…
user10178
109
votes
10 answers
Properly setting up a "default" nginx server for https
I have several servers running on the same machine, some with http only, some with both http and https. There are several server blocks defined in separate files which are included from the main config file.
I have set up a "default" server for…
Roar