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1500 questions
103
votes
1 answer
How do I validate an RSA SSH public key file (id_rsa.pub)?
Is there a command I can use to verify the public key (id_rsa.pub), just the format only.
Sometimes I have added a new linebreak, sometimes the file missed the ssh-rsa prefix, so is there a command to validate with?
Ryan
- 6,271
103
votes
18 answers
Caching/preloading files on Linux into RAM
I have a rather old server that has 4GB of RAM and it is pretty much serving the same files all day, but it is doing so from the hard drive while 3GBs of RAM are "free".
Anyone who has ever tried running a ram-drive can witness that It's awesome in…
Andrioid
- 2,760
103
votes
11 answers
Testing UDP port connectivity
I am trying to test whether I can get to a particular port on a remote server (both of which I have access to) through UDP.
Both servers are internet facing.
I am using netcat to have a certain port listening.
I then use nmap to check for that port…
Lock
- 1,787
103
votes
2 answers
IPTABLES - Limit rate of a specific incoming IP
I do not wish to limit the rate of a specific service. My goals is to limit rate based solely on the incoming IP address. For example using a pseudo-rule:
john.domain.local (192.168.1.100) can only download from our httpd/ftp servers at "10KB/s"…
James
- 1,117
103
votes
8 answers
Can you have more than one ~/.ssh/config file?
We have a bastion server that we use to connect to multiple hosts, and our .ssh/config has grown to over a thousand lines (we have hundreds of hosts that we connect to). This is beginning to get a little unwieldy and I'd like to know if there is a…
wrangler
- 3,300
103
votes
11 answers
How to zip/unzip files in Powershell?
Is there a one-liner that will zip/unzip files (*.zip) in PowerShell?
BlueGene
- 2,241
103
votes
8 answers
How to make bash scripts print out every command before it executes?
For example, I have a simple bash file
#!/bin/bash
cd ~/hello
ls
How can I make it display every command before executing it? Just the opposite effect of "@echo off" in windows batch scripting.
Epeius
- 1,041
103
votes
11 answers
How to prevent a user from login in, but allow "su - user" in Linux?
How do you allow a user to log in using "su - user" but prevent the user from login in using SSH?
I tried to set the shell to /bin/false but the when I try to su it doesn't work.
Are there several ways to only allow logins by su?
Is SSH's AllowUser…
NoozNooz42
- 1,195
103
votes
9 answers
mysqldump to a tar.gz
Usually after dumping a MySQL database with mysqldump command I immediately tar/gzip the resultant file. I'm looking for a way to do this in one command:
So from this:
mysqldump dbname -u root -p > dbname.sql
tar czvf dbname.sql.tgz dbname.sql
rm…
pygorex1
- 1,211
103
votes
9 answers
How can I fully log all bash scripts actions?
From my script output I want to capture ALL the logs data with error messages and redirect them all to log file.
I have script like below:
#!/bin/bash
(
echo " `date` : part 1 - start "
ssh -f admin@server.com 'bash…
BlueMark
- 1,169
102
votes
4 answers
How to filter http traffic in Wireshark?
I suspect my server has a huge load of http requests from its clients.
I want to measure the volume of http traffic.
How can I do it with Wireshark?
Or probably there is an alternative solution using another tool?
This is how a single http…
par
- 1,273
102
votes
4 answers
"413 Request Entity Too Large" in Nginx with "client_max_body_size" set
I am uploading a 26Gb file, but I am getting:
413 Request Entity Too Large
I know, this is related to client_max_body_size, so I have this parameter set to 30000M.
location /supercap {
root /media/ss/synology_office/server_Seq-Cap/;
index…
user2979409
- 1,121
102
votes
2 answers
How can I send a message to the systemd journal from the command line?
In older Linux systems, the logger command can be used to send a log message to syslog.
Reading where does logger log its messages to in Arch Linux?, it seems that syslog messages and the logger command line app only talk to the systemd journal if a…
mikemaccana
- 3,710
102
votes
10 answers
How do I do Multihop SCP transfers between machines?
I want to copy a file from my machine A to server C, but only have access to server C through server B.
Instead of first transferring to server B, log in and then transfer to server C, Is is possible to transfer the file directly with SCP or similar…
sverrejoh
- 1,121
102
votes
11 answers
Cooling Server Closet - No A/C Is Possible
We're moving into a new office in an old building in London (that's England :) and are walling off a 2m x 1.3m area where the router & telephone equipment currently terminates to use as a server closet. The closet will contain:
2 24-port switches…
JamesCo
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