Greatest Hits
705
votes
9
answers
2.1m
views
How to automate SSH login with password?
How to automate SSH login with password?
I'm configuring my test VM, so heavy security is not considered. SSH chosen for acceptable security with minimal configuration.
ex)
echo password | ssh id@...
- 10k
1752
votes
3
answers
2.0m
views
What is a Pem file and how does it differ from other OpenSSL Generated Key File Formats?
I am responsible for maintaining two Debian servers. Every time I have to do anything with security certificates, I Google for tutorials and beat away until it finally works.
However, in my searches ...
- 19k
801
votes
18
answers
2.7m
views
Ping a Specific Port
Just a quick sanity check here.
Can you ping a specific port of a machine, and if so, can you provide an example?
I'm looking for something like ping ip address portNum.
- 8,135
1377
votes
39
answers
1.1m
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 -...
- 17.1k
765
votes
9
answers
1.0m
views
Can scp copy directories recursively?
Currently I can only copy a single .tar file. But how can I copy directories recursively with scp?
- 8,361
2455
votes
31
answers
520k
views
Our security auditor is an idiot. How do I give him the information he wants?
A security auditor for our servers has demanded the following within two weeks:
A list of current usernames and plain-text passwords for all user accounts on all servers
A list of all password ...
- 24.1k
947
votes
15
answers
1.3m
views
How to determine if a bash variable is empty?
What is the best way to determine if a variable in bash is empty ("")?
I have heard that it is recommended that I do if [ "x$variable" = "x" ]
Is that the correct way? (there must be something more ...
- 22.5k
549
votes
32
answers
1.1m
views
How do I tell Git for Windows where to find my private RSA key?
My Git setup runs fine on Linux, but when I try to set things up under Windows (using Git for Windows and TortoiseGit), I don't know where to put my private SSH key (or, better still, how to tell ssh ...
- 5,951
469
votes
5
answers
1.2m
views
What's the default superuser username/password for postgres after a new install?
I have just installed postgres 8.4 on Ubuntu 9.10 and it has never asked me to create a superuser. Is there a default superuser and its password? If not, how do I create a new one?
- 6,141
153
votes
9
answers
1.2m
views
Command line to list users in a Windows Active Directory group?
Is there a command line way to list all the users in a particular Active Directory group?
I can see who is in the group by going to Manage Computer --> Local User / Groups --> Groups and double ...
Flyer
327
votes
5
answers
861k
views
How to send ctrl+alt+del using Remote Desktop?
How can I send ctrl+alt+del to a remote computer over Remote Desktop?
For example, if I wanted to change the local admin password on a remote PC using a Remote Desktop connection, it would be helpful ...
- 3,373
561
votes
6
answers
485k
views
ssh returns "Bad owner or permissions on ~/.ssh/config"
When I try to ssh to another box, I get this strange error
$ ssh hostname
Bad owner or permissions on ~/.ssh/config
But I made sure that I own and have rw permissions on the file:
ls -la ~/.ssh/
...
- 14.5k
460
votes
22
answers
312k
views
mysqldump throws: Unknown table 'COLUMN_STATISTICS' in information_schema (1109)
Every time I try to make a mysqldump I get the following error:
$> mysqldump --single-transaction --host host -u user -p db > db.sql
mysqldump: Couldn't execute 'SELECT COLUMN_NAME, ...
- 5,679
69
votes
11
answers
211k
views
How do I check if Log4j is installed on my server?
I have read about security vulnerabilities related to Log4j.
How do I check if Log4j is installed on my server?
My specific servers use Ubuntu 18.04.6 LTS.
I have installed many third-party packages ...
- 841
238
votes
5
answers
1.2m
views
Can you pass user/pass for HTTP Basic Authentication in URL parameters?
I believe this is not possible, but someone I know insisted that it works. I don't even know what parameters to try, and I haven't found this documented anywhere.
I tried http://myserver.com/~user=...
- 5,780
619
votes
18
answers
867k
views
How do you find what process is holding a file open in Windows?
One thing that annoys me no end about Windows is the old sharing violation error. Often you can't identify what's holding it open. Usually it's just an editor or explorer just pointing to a relevant ...
- 9,849
283
votes
7
answers
1.3m
views
Check if port is open or closed on a Linux server?
How can I check if a port is listening on a Linux server?
- 2,997
385
votes
27
answers
433k
views
How can I get the size of an Amazon S3 bucket?
I'd like to graph the size (in bytes, and # of items) of an Amazon S3 bucket and am looking for an efficient way to get the data.
The s3cmd tools provide a way to get the total file size using s3cmd ...
- 4,305
187
votes
9
answers
1.1m
views
Resolve host name from IP address
I'm looking for a command line tool which gets an IP address and returns the host name, for Windows.
- 1,993
183
votes
6
answers
1.3m
views
148
votes
2
answers
925k
views
What causes the 'Connection Refused' message?
This is a Canonical Question about Connection Refused
We see a lot of questions to the effect
When I try to connect to a system I get a message
Connection refused
Why is this ?
- 115k
369
votes
7
answers
848k
views
Why is my crontab not working, and how can I troubleshoot it?
This is a Canonical Question about using cron & crontab.
You have been directed here because the community is fairly sure that the answer to your question can be found below. If your question is ...
- 4,101
206
votes
11
answers
586k
views
"Add correct host key in known_hosts" / multiple ssh host keys per hostname?
Trying to ssh into a computer I control, I'm getting the familiar message:
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @
@@@@@...
- 2,243
61
votes
14
answers
403k
views
What causes SSH error: kex_exchange_identification: Connection closed by remote host?
I setup a SSH server online that is publicly accessible by anyone. Therefore, I get a lot of connections from IPs all over the world. Weirdly, none actually try to authenticate to open a session.
I ...
- 713
551
votes
11
answers
569k
views
In Nginx, how can I rewrite all http requests to https while maintaining sub-domain?
I want to rewrite all http requests on my web server to be https requests, I started with the following:
server {
listen 80;
location / {
rewrite ^(.*) https://mysite.com$1 ...
- 8,362
122
votes
13
answers
1.1m
views
How do I force sync the time on Windows Workstation or Server?
What is the command to sync a Windows workstation or server to its configured time source?
- 82.8k
296
votes
5
answers
629k
views
Nginx reverse proxy + URL rewrite
Nginx is running on port 80, and I'm using it to reverse proxy URLs with path /foo to port 3200 this way:
location /foo {
proxy_pass http://localhost:3200;
...
- 3,125
390
votes
14
answers
655k
views
Displaying a remote SSL certificate details using CLI tools
In Chrome, clicking on the green HTTPS lock icon opens a window with the certificate details:
When I tried the same with cURL, I got only some of the information:
$ curl -vvI https://gnupg.org
* ...
- 12.8k
252
votes
11
answers
529k
views
Docker Container time & timezone (will not reflect changes)
Where do Docker containers get their time information? I've created some containers from the basic ubuntu:trusty image, and when I run it and request 'date', I get UTC time.
For awhile I got around ...
- 2,663
125
votes
35
answers
458k
views
SSH Suddenly returning Invalid format
So a while ago I set up a server on AWS, and used their generated SSH key. I saved the key to Lastpass, and have successfully retrieved it from there before, and got it working. However, after trying ...
- 1,353
300
votes
14
answers
957k
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 look-...
- 3,135
76
votes
15
answers
628k
views
Get list of AD groups a user is a member of
Suppose I have the user id of a user in Active Directory. I'd like to get a list of all AD groups in which that user is currently a member of. How can I do this from the Windows command line?
I've ...
- 1,924
152
votes
5
answers
241k
views
What is the difference between authentication and authorization?
Basic question from a novice:
What is the difference between authentication and authorization?
Kyy
58
votes
8
answers
631k
views
What does "TTL expired in transit" mean on a ping attempt?
We get the message “TTL expired in transit” when we try to ping to a server in a different network segment. When we run tracert, 4 ip addresses repeat themselves indefinitely:
14 60 ms 59 ms ...
- 685
281
votes
15
answers
654k
views
How to Unban an IP properly with Fail2Ban
I'm using Fail2Ban on a server and I'm wondering how to unban an IP properly.
I know I can work with IPTables directly: iptables -D fail2ban-ssh <number>
But is there not a way to do it with ...
- 3,073
190
votes
6
answers
657k
views
VirtualBox: How to set up networking so both host and guest can access internet and talk to each other
I was wondering if someone could give me a simple guide on how to set up virtual networking in VirtualBox (4.0.2) so that the following scenarios work:
Both Host and Guest can access the Internet
...
- 6,757
146
votes
3
answers
188k
views
How can I upgrade to Java 1.8 on an Amazon Linux Server?
I tried sudo yum update but it just keeps java "1.7.0_75". I need 1.8 for it to work with another application but can't figure out how to upgrade it.
Do I need to manually install it somehow? There's ...
- 1,463
205
votes
13
answers
524k
views
hosts file ignored, how to troubleshoot?
The hosts file on Windows computers is used to bind certain name strings to specific IP addresses to override other name resolution methods.
Often, one decides to change the hosts file, and discovers ...
- 5,115
273
votes
15
answers
501k
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 ...
Anna
123
votes
4
answers
991k
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?
- 1,343
25
votes
9
answers
315k
views
Span on multiple monitors when logged into a Citrix session via Citrix Receiver (or Citrix server)
I am using the Citrix Receiver in Windows 8, and on Windows XP on another PC. I often log into work from home and am unable to span the session to dual monitors like one can easily do when using "...
- 1,924
228
votes
17
answers
716k
views
Permission denied (publickey). SSH from local Ubuntu to Amazon EC2 server
I have an instance of an application running in the cloud on an Amazon EC2 instance, and I need to connect to it from my local Ubuntu. It works fine on one local ubuntu and also laptop. I got this ...
- 2,421
241
votes
8
answers
844k
views
How do I add Access-Control-Allow-Origin in NGINX?
How do I set the Access-Control-Allow-Origin header so I can use web-fonts from my subdomain on my main domain?
Notes:
You'll find examples of this and other headers for most HTTP servers in the ...
- 3,319
192
votes
9
answers
903k
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 ...
- 3,475
561
votes
3
answers
304k
views
What exactly do the colors in htop status bars mean?
By default, htop shows colored status bars for processors, memory, and swap. From left to right, the bars are colored green, blue, yellow, and red depending on some thresholds.
What does it mean when ...
- 6,051
90
votes
6
answers
755k
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 ...
- 1,607
366
votes
6
answers
542k
views
What permissions should my website files/folders have on a Linux webserver?
This is a Canonical Question about File Permissions on a Linux web server.
I have a Linux web server running Apache2 that hosts several websites. Each website has its own folder in /var/www/.
/var/...
- 13.2k
27
votes
4
answers
220k
views
Outlook 2013: how to reset to "first run" status?
TL;DR
Is there a way via script, powershell, reg delete, via telekinesis, whatever to reset Outlook 2013 as if no profiles ever existed and it was running for the first time ever?
Still working ...
- 32.5k
345
votes
18
answers
543k
views
How do I get the current Unix time in milliseconds in Bash?
How do I get the current Unix time in milliseconds (i.e number of milliseconds since Unix epoch January 1 1970)?
- 3,732
161
votes
4
answers
214k
views
Getting "Cannot ioctl TUNSETIFF tun: Operation not permitted" when trying to connect to OpenVPN
I'm trying to setup an OpenVPN Access Server in AWS using the market place AMI, but I;m struggling to connect to it.
The access server is up and running. I've also added a user with Auto-Login and ...
- 5,735