Testing Port Connectivity from Photon OS
VMware appliances do come with wget and this can be used to check connectivity to TCP ports:
wget server:port
Netcat is a much better tool for this that can test UDP connectivity:
https://www.digitalocean.com/community/tutorials/how-to-use-netcat-to-establish-and-test-tcp-and-udp-connections

Create a private key and certificate signing request:
openssl req -new -newkey rsa:2048 -nodes -keyout hostname.key -out hostname.csr

How to run firefly wtihout GPU error:
Run the program with the --no-sandbox parameter.

Copying a file from Linux to Windows using SMBClient
apt-get install smbclient
/usr/bin/smbclient \\\\windows-hostname\\sharename --user=username -c 'put "Setup_MartinHippo.exe"'

How to Extend a Partition with Parted
parted /dev/sdb

Resize partition (the first one in this example):
resizepart 1 100% 
If 100% doesn't work try:
resizepart 1 -1
If that doesn't work you need to enter the desired capacity in MB.

File system check prior to extending partition:
e2fsck -f /dev/sdb1

Expand the filesystem:
resize2fs /dev/sdb1

View all banned IPs by fail2ban:
fail2ban-client status sshd

Unban all IPs:
fail2ban-client unban --all

Recursively search all files for a string:
find . -type f -exec grep -l 'some-string' {} \;

Find text in a single file:
grep -Ri some-string fail2ban.log

Set grub password:
grub2-setpassword 
cat /boot/grub2/user.cfg
grub2-mkconfig -o /boot/grub2/grub.cfg