A comprehensive list of the top 25 Active Directory Security Tips and best practices. Securing domain admins, local administrators, audit policies, monitoring AD for compromise, password policies, vulnerability scanning and more.
This AWS Article will show you how to secure, rotate, and use SSH keypairs for inter-cluster communication. You’ll use an AWS CloudFormation template to launch a cluster and configure Secrets Manager. Then we’ll show you how to use Secrets Manager to deliver the keypair to the cluster and use it for management operations, such as securely copying a file between nodes. Finally, we’ll use Secrets Manager to seamlessly rotate the keypair used by the cluster without any changes or outages. In this post, we’ve highlighted compute clusters, but you can use Secrets Manager to apply this solution directly to any SSH based use-case.
When installing an SSL certificate on a server you should install all intermediate certificates as well. Paste or upload your certificate to generate a .crt-file with all intermediate certificates concatenated.
All operating systems contain a set of default trusted root certificates.
But Certificate Authorities usually don’t use their root certificate to sign customer certificates.
They use so called intermediate certificates instead, because these can be rotated more frequently.
If not all intermediate certificates are installed on your server, some clients —mostly mobile browsers— will think you are on an insecure connection.
dnstwister generates a list of domain names that are similar to one that you provide, checking to see if any of them are registered.
dnstwister can tell you if someone may be using a domain like yours for malicious purposes like phishing or trademark infringement.
For instance as the owner of the domain dnstwister.report I would be very interested to know if someone registered the ‘dnstw1ster.report’ domain and started sending malicious password-reset emails to users.
Ideally you should whitelist your SSH Servers to your IPs or don’t even expose the service to the Internet and use a VPN to login. In some cases this is not an option and/or you may need to create a Bastion Host / Jump Box server with SSH exposed.
If this is the case you should do or at least consider these options:
Change the SSH port (May reduce the noise, but not the security)
Only use Key Based Authentication i.e. disable password and use keys only
Prevent root user from logging in via SSH
Limit user access via SSH
Once the above has been completed, use SSH Audit to check that everything from an SSH configuration is setup correctly and passes the security checks. SSH Audit is a free online tool allows you to audit the configuration of an SSH server.
grepcidr can be used to filter a list of IP addresses against one or more Classless Inter-Domain Routing (CIDR) specifications. As with grep, there are options to invert matching and load patterns from a file. grepcidr is capable of efficiently processing large numbers of IPs and networks.
grepcidr has endless uses in network software, including: mail filtering and processing, network security, log analysis, and many custom applications.
For detailed instructions and examples, please see the README file or man page. A couple examples of usage:
For years I’ve used ncdu a NCurses Disk Usage utility for Linux. Recently someone alerted me to some other options as well as ncdu:
Dust: du + rust = dust. Like du but more intuitive, Dust is meant to give you an instant overview of which directories are using disk space without requiring sort or head. Dust will print a maximum of 1 ‘Did not have permissions message’. Dust will list the 20 biggest sub directories or files and will smartly recurse down the tree to find the larger ones. There is no need for a ‘-d’ flag or a ‘-h’ flag. The largest sub directory will have its size shown in red.
NCDU: Ncdu is a disk usage analyzer with an ncurses interface. It is designed to find space hogs on a remote server where you don’t have an entire graphical setup available, but it is a useful tool even on regular desktop systems. Ncdu aims to be fast, simple and easy to use, and should be able to run in any minimal POSIX-like environment with ncurses installed.
Install from repos: sudo apt install ncdu