Always Geeky

Copying Linux encrypted shadow password

If you need to copy a Linux user account from one system to another and need to presever the password without knowing it, you can use this process.

First, create the user:

sudo useradd bob

Set group membership as required, such as appending the wheel group:

sudo usermod -a -G...Read More »

apt-get error: Ignoring Provides line with DepCompareOp for package

Receiving the following error, includes the message that running “apt-get update” should fix it. It doesn’t, as that command generates the same error.

W: Ignoring Provides line with DepCompareOp for package libjpeg62 8,790 kB/s 0s
W: Ignoring Provides line with DepCompareOp for package php-psr-http-message-implementation
W: Ignoring Provides line with DepCompareOp...Read More »

Using rsync to ensure 2 directories match

rsync -nrhc --progress /home/user/source/docs/ /home/user/destination/docs/

How to generate a pre shared key using APG

A common requirement is to generate a random, unique and secure pre-shared key, typically for use in VPN’s. The Linux tool, APG (Automated Password Generator), is a great tool for this job, but you need to specify a few options to get the correct output.

TCP dump without truncating

If you receive the following error while performing a packet capture with tcpdump, there is a solution.

    Packet size limited during capture

    sudo tcpdump -i any -w capture.pcap...Read More »

Useful openssl commands

View certificate attributes, such as common name (domain name), subject alternate name, issued by, expiry date, issued to, etc.

openssl x509 -in cert.crt -noout -text

diff < (openssl x509 -in certificate.crt -noout -modulus) <(openssl rsa -in privatekey.key -noout -modulus)

curl with multiple HTTP headers

If you need to set multiple HTTP headers when using curl, you cannot do so by delimiting them with a CRLF or similar line break. Doing so won’t work. You must set each header within a distinct -H parameter.