by lunarg on September 18th 2019, at 12:02
When adding a new disk to a live system (e.g. a linux VM), the new disk may not always show up. Additionally, when resizing a disk through the hypervisor, the VM may not always immediately have the new size available for use. Luckily, you can trigger a rescan of the SCSI bus through the sysfs system.

For this to work, you'll need to have shell and root access to the server/VM.

Modern linux kernels automatically detect the addition of a disk, but in case it doesn't, you can trigger a rescan of a specific (virtual) SCSI controller:

echo "- - -" > /sys/class/scsi_host/hostX/scan

Replace hostX with the number of the SCSI controller, where host0 is the first, host1 is the second, et  ...
by lunarg on September 13th 2019, at 10:55
To quickly block traffic from/to a specific IPv4 address using iptables, you can use the commands below.

Do not use these commands when you are already running an iptables-based firewall as this may result in unexpected results.

Block incoming traffic from a specific IP:

iptables -A INPUT -s -j DROP

Block outgoing traffic (i.e. traffic initiated from the host itself) to a specific IP:

iptables -A OUTPUT -d -j DROP

To block outgoing traffic to a specific port and protocol, you can also do something like this (the example below blocks DNS and HTTP):

/sbin/iptables -A OUTPUT -p tcp --dport 80 -d -j DROP/sbin/iptables -A OUTPUT -p udp --dport 53 -d  ...
by lunarg on September 9th 2019, at 16:54
On VCSA, the database is stored on a separate disk. It could happen that this disk runs out of room, causing Vcenter to no longer function properly. One way to resolve this is by running database clean up as mentioned in KB 2110031. However, if this is not possible, or you don't want to clear out the data, you can also resize the disk.

For this to work, you'll need root access and access to the bash-shell, either on the console or through SSH.

Before resizing, identify the physical disk to be resized. For VCSA 6.5 and 6.7, this should normally be Disk 8 (device node in linux = /dev/sdh), but your setup may vary, so it's best to double-check this.

In VCSA 6.5 and 6.7, the database is locat  ...
by lunarg on September 9th 2019, at 12:45
Handling snapshots (creating, deleting, restoring) is rather intuitive when you already have some experience with PowerCLI. As a reference, here are some one-liners. As always with Powershell, there's more than one way to achieve a goal... The examples used here assume a VM named "SRV01". Adjust as needed.

Create a snapshot:

Get-VM SRV01 | New-Snapshot -Name "My snapshot"

Remove all snapshots (disabling confirmation request in the process):

Get-VM SRV01 | Get-Snapshot | Remove-Snapshot -Confirm:$false

To handle a specific snapshot, you could do something like this:

$vm = Get-VM SRV01$snap = Get-Snapshot -VM $vm -Name "My snapshot"# do something with the sn  ...
by lunarg on September 5th 2019, at 16:43
For users which really want to prevent Windows 10 from automatically installing updates, here are some methods to disable automatic updates. Depending on which method you use, you will still be able to manually check and install updates, or not be able to install updates at all...

Note that the methods leverage group policies, which is not supported on Windows 10 "Home/Essential" editions. A minimum of Windows 10 Pro or better is needed.

It is generally not recommended to disable automatic updates. Doing so (and not subsequently regularly installing the updates yourself) increases the risk of data loss and/or stealing due to potentional vulnerabilities in Windows 10.

The  ...
by lunarg on August 29th 2019, at 11:29
There's an easy method for extracting hard disk S.M.A.R.T. testing logs using the CLI. This is useful if you require support on Synology and need an easier method to get the data (other than creating screenshots from your web-browser), and if more detailed data is needed.

Before getting the logs from the CLI, first run an extended SMART analysis from the DSM. This will take a while (usually several hours). Running the analysis on multiple disks is possible and can be done concurrently, but it needs to be initiated manually for each disk.

Once tests have completed, log onto the CLI (using your favourite SSH client, such as PuTTY) using the "admin" or "root" account.

As   ...
by lunarg on July 23rd 2019, at 09:54
To quickly generate a self-signed certificate, follow the steps below. Note that self-signed certificates should be avoided in production environments.

Generate the private key (here, 1024-bit is used, but you can change that to lower/higher):

openssl genrsa –out ca.key 1024

Generate the certificate signing request:

openssl req –new –key ca.key –out ca.csr

You will be asked for information to include in the signing request:

Country name (2 letters)

State or province

Full locality name (city)

Organization name

Department / organizational unit

Common name (or distinguished name): should be set to the FQDN of your server

E-mail address: set to a local contact (usually the sy  ...
by lunarg on June 7th 2019, at 11:22

If you need to rename all folders and files to lowercase on a case-sensitive filesystem (e.g. ext4 on linux), you can use the following at the bash prompt:

If rename is available (if you have Perl installed, then it usually is):

find . -depth -exec rename 's/(.*)\/([^\/]*)/$1\/\L$2/' {} \;

If you can't use rename, try this:

for SRC in `find my_root_dir -depth`
    DST=`dirname "${SRC}"`/`basename "${SRC}" | tr '[A-Z]' '[a-z]'`
    if [ "${SRC}" != "${DST}" ]
        [ ! -e "${DST}" ] && mv -T "${SRC}" "${DST}" || echo "${SRC} was not renamed"
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