A Technical I.T./DevOps Blog
Question
What are guardrails in the I.T. industry?
Answer
A measure, technology or authentication policy in place to prevent problems in an enterprise network or with a application. With guardrails, a server or web application is protected from hackers or accidental misuse. It is a common metaphor based on highway guardrails. To learn more, see this posting:
https://devops.com/building-great-cloud-security-guardrails/
There is a specific product called GUARDRAILS that detects,
…
Question
You want an overview of how SSH works because it seems confusing. You want to comprehend how it works or know exactly what happens when you run an SSH command like ssh jdoe@acme.com. Where can you find a precise explanation on using ssh as well as some background information on SSH?
Solution
SSH is named after the secure shell way of remotely connecting to another server using encryption.
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Problem scenario
You run a terraform command. You get ‘unsupported argument aws_key_pair’. You want terraform to create an EC-2 server with a specific key pair. What should you do?
Solution
Don’t use “aws_key_pair”, use “key_name”. The aws_instance section in a .tf file uses a different keyword. (The aws_key_pair is for creating an key-pair in AWS.) Use the “key_name” field for aws_instances like this:
resource “aws_instance” “example” {
ami = “ami-01a1234abcd567”
instance_type = “t2.micro”
key_name = “appleorange”
} …
Continue reading “How Do You Troubleshoot the Terraform Error ‘unsupported argument aws_key_pair’?”
Question
Some companies are getting away from VPNs in favor of zero trust systems. It can help save money on bandwidth and facilitate a better network performance when every employee is working remotely. Are NoVPN Services More Secure for a Given Enterprise? Is it recommended to use non-VPN services?
Answer
We think this is a debatable whether VPNs (Virtual Private Networks) make systems more secure.
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Continue reading “Are Zero Trust Networks More Secure than VPN-Protected Networks?”
Question
You hear and read about companies that always use best practices. If you use best practices, is your data safe?
Answer
No.
In 2014 many people respected Akamai Technologies, Amazon Web Services, GitHub, Pinterest, Bitbucket, Reddit, SourceForge,
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Problem scenario
You are trying to find the SSH logs in Fedora. Where should you look?
Possible solution #1
/var/log/secure/
Possible solution #2
Check these locations:
/var/log/ssh/
/var/log/auth.log
Possible solution #3
/var/log/messages
(Many other applications write to this file besides SSH.)
Possible solution #4
They could be stored in binary format in /var/log/journal/ …
Run this command: journalctl -u sshd
Look at the output.
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Problem scenario
A server is hosting a website. On the server, nmap -Pn x.x.x.x is showing port 80 is listening on the server itself. From another server this nmap -Pn x.x.x.x command is showing no ports (or a subset of the ports) are listening. What is the cause of this?
Possible Solution #1
There is a firewall on the webserver that is causing this.
…
Continue reading “How Do You Troubleshoot Connectivity over Port 80 when You Know It Is Listening?”
Problem scenario
You need to make a Linux server very secure. How do you harden a Linux server?
Answer
…
Continue reading “How Do You Secure or Harden a Linux Server?”
Problem Scenario
You want to modify a security group to allow SSH connections from an IP address. How do you do this with the AWS CLI?
Solution
You have to know the security group’s ID. Replace “sg-abcd1234” with the group ID, and replace 1.2.3.0/24 with the IP address and subnet mask you want to allow to connect from in this command and then run it:
aws ec2 authorize-security-group-ingress \
–group-id sg-abcd1234 \
–protocol tcp \
–port 22 \
–cidr 1.2.3.0/24
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Question
This website (https://kb.iu.edu/d/aews) says “On the SSH command line: Add the -i flag and the path to your private key.”
When running an SSH command, you do not think that the client’s private key would not come into play. You think that the public key would be used. The man page for SSH says
-i identity_file
Selects a file from which the identity (private key) for public key authentication is read
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ssh will also try to load certificate information from the filename obtained by appending -cert.pub to identity filenames.
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Continue reading “Is a Private Key on a Linux Client Used in SSH Authentication to a Remote Server?”