Docker Copy Files

When building a Docker image using the Dockerfile, if you need to copy some files from the Docker Engine machine to the Docker Image, you need to use the "correct" source path where the files are located.

Let's say you have the following files:

/mydocker/Dockerfile
/mydocker/file1.sh
/mydocker/file2.sh

you can't specify the following command within your Dockerfile

COPY /mydocker/file1.sh /etc/
COPY /mydocker/file2.sh /etc/

instead, you need to do the following

mkdir /mydocker/resources
mv /mydocker/file1.sh /mydocker/resources
mv /mydocker/file2.sh /mydocker/resources

then, in your Dockerfile, specify the following COPY command

COPY resources /etc/

Microsoft Ignite Sydney 2019

Windows Server Core 2019 - Remote PowerShell

Just installed a couple of Windows Server Core 2019. To manage them through PowerShell remotely, you need to enable PowerShell Remoting

On the Windows Server 2019 Core, run the following command

> Enable-PSRemoting -Force

The remote machine from which you want to manage the server

> Enter-PSSession -Credential (Get-Credential) -ComputerName my2019server.domain.tld

Enjoy!

Westpac Super.Tech Q4 Individual Award Winner

And to close the year 2018, I have been nominated and won the Q4 Individual Award! 

It has been a long and challenging year for me :)

CISM

Passed CISM exam today, yay!!

Westpac CISO Award

Got another one CISO Award !!

Cleaning Up CSC Folders

C:\Windows\CSC folder is the offline files folder. It has special permissions. Without the correct permission, you won't be able to delete anything in it

To delete the content of C:\Windows\CSC, you need to modify its permissions

> cd c:\Windows
> takeown /f CSC /r /a /d y
> icacls CSC /grant Administrators:F

Then you can navigate to the folder and start deleting files

Publish TeamCity via Sophos XG Firewall

I am running TeamCity product at home for my development work and would like to publish the site via my Sophos XG Firewall. TeamCity runs on the internal domain namespace and to publish it to the Internet, you need to configure it so that it recognises the external domain namespace.

I don't want to make any change on the TeamCity, and luckily Sophos can do it !

Create Business Application Rule on your Sophos Firewall make sure the "Rewrite HTML" is selected as shown below. That's it!

Westpac Super.Tech Q3 Team Award Winner

My project team has been nominated and won the Q3 Team Award! 

I am very proud to be part of the team that made one of the most complicated and long-running global projects completed successfully.

OpenSSL to Retrieve Certificate

It is very easy to retrieve TLS/SSL certificate bound to a web server. You can use any Internet browser to navigate to the site and then you can view the certificate.

How do you get a certificate details from a non-HTTP endpoints? like LDAP for example.
Fortunately, you can use OpenSSL to retrieve the certificate

> openssl s_client -connect address-of-the-endpoint:636

Enjoy!

SSH Login Notification with SSMTP

I have my box to send email notification for every successful SSH login in the past here.
It requires sendmail to be installed, which is too much I think just to send email out from the box.

I found a lighter way to do it, using ssmtp package:

edit/create the file:
> sudo vi /etc/ssh/sshrc

DATE=`date "+%d.%m.%Y--%Hh%Mm"`
IP=`echo $SSH_CONNECTION | awk '{print $1}'`
REVERSE=`dig -x $IP +short`

echo "To: laurence.lau@domain.tld" > /tmp/mail.content
echo "From: Beaver <beaver@domain.tld>" >> /tmp/mail.content
echo "Subject: SSH Login Succcessful" >> /tmp/mail.content
echo "" >> /tmp/mail.content
echo "$DATE, user $USER just logged in from $IP ($REVERSE)" >> /tmp/mail.content
ssmtp laurence.lau@domain.tld < /tmp/mail.content &

edit the file:
> sudo vi /etc/ssmtp/ssmtp.conf

mailhub=smtprelay.domain.tld:25

PowerShell RunAs

To execute PowerShell to Run As a different credential:

> $cred = Get-Credential
> Start-Process powershell.exe -Credential $cred -NoNewWindow -ArgumentList "-noprofile -command &{Start-Process -FilePath C:\blah\prog.exe}"

PowerShell SecureString

PowerShell is often used to access data from systems or apps that require authentication. Authentication requires username and password. you don't want to store the password in the PowerShell script itself.

The better way is to store the password as SecureString in a configuration file and use that to access the data / app.

To generate the configuration file:

>  Read-Host -AsSecureString | ConvertFrom-SecureString | Out-File C:\Securestring.txt

To consume the configuration file:

> $pass = Get-Content C:\Securestring.txt | ConvertTo-SecureString

To convert it as credential object:

> $cred= New-Object -TypeName System.Management.Automation.PSCredential -ArgumentList "username",$pass

Windows 2016 Core Domain Controllers

Upgrading my Domain Controllers from 2012 R2 to 2016. I have decided to run the servers without Desktop Experience to save resources.

Once installed, run the "sconfig" utility from the CMD to setup the server name, IP address, DNS and gateway, then reboot

To add AD Domain Services feature:

Add-WindowsFeature AD-Domain-Services

To install AD Forest::

Install-ADDSForest -CreateDnsDelegation:$false
-DatabasePath C:\Windows\NTDS
-DomainMode WinThreshold
-DomainName domain.tld
-DomainNetbiosName NETBIOSDOMAIN
-ForestMode WinThreshold
-InstallDns:$true
-LogPath C:\Windows\NTDS
-NoRebootOnCompletion:$true
-SysvolPath C:\Windows\SYSVOL
-Force:$true

ForestMode = WinThreshold = for Windows 2016

To add AD Domain Controller to the existing domain:

Install-ADDSDomainController -CreateDnsDelegation:$false 
-DatabasePath C:\Windows\NTDS
-DomainName domain.tld
-InstallDns:$true 
-LogPath C:\Windows\NTDS
-NoGlobalCatalog:$false 
-SysvolPath C:\Windows\SYSVOL
-NoRebootOnCompletion:$true 
-Force:$true
-Credential (Get-Credential)

AWS Certified Solutions Architect - Associate

New year, 2018! New challenges!!

Passed the exam and now I am officially AWS Certified Solutions Architect - Associate. Next is Professional #StayTune

Let's Encrypt Certificate Renewal

To renew the certificate that was generated by Let's Encrypt:

1# Go to sslzero.com site
2# Use the same Let's Encrypt Key generated by the site when certificate was originated
3# Get the CSR
4# That's it

Proxy PAC Tester v.2.0

New version of Proxy PAC Tester that supports client IP address to be passed to some of the JS function that checks against client IP address.

#LoveCoding

Active Directory GUID

Active Directory GUID is stored as Byte array (Byte[]).

To convert from Byte[] to string:

string guid = new Guid(Byte[] Object).ToString()

To convert from string to Byte[]:

string guid = <string guid here>

Guid g = Guid.Parse(guid);
Byte[] gba = g.ToByteArray();

string result = "";
foreach(Byte b in gba){ result += @"\" + b.ToString("x2"); }

GUID String to Octect String

If you need to perform LDAP query against Active Directory with objectGUID as the filter, you need to convert the string representation of that GUID to octetstring.

For example, if the objectGUID string value is: ffe17244-4c77-48e7-9db7-69578be7e232
You need to convert it to: \44\72\e1\ff\77\4c\e7\48\9d\b7\69\57\8b\e7\e2\32

so then you can provide the LDAP filter with:
(objectGUID=\44\72\e1\ff\77\4c\e7\48\9d\b7\69\57\8b\e7\e2\32)

To do this by C#, use the following function:

        private string convertStringGuidToOctectString(string guid)
        {
            Guid g = Guid.Parse(guid);
            Byte[] gba = g.ToByteArray();

            string result = "";
            foreach (Byte b in gba)
            {
                result = result + @"\" + b.ToString("x2");
            }

            return result;
        }

Good luck!

Let's Encrypt and Sophos XG Firewall

I am publishing my web server behind the Sophos XG firewall. I need SSL certificate that is free and trusted by most of internet browsers. The answer is Let's Encrypt.

I use this site to help integrate with Let's Encrypt : http://zerossl.com

Steps
#1 Generate CSR from the XG firewall and download the CSR and the private key
#2 Navigate to zerossl.com and paste the CSR content
#3 Follow the instruction to validate your domain - I did DNS option by inserting TXT value
#4 Once validation is successful, the signed public key is ready to be downloaded
#5 Upload the signed key to XG firewall along with the private key that was downloaded on step #1
#6 (optional) if XG firewall does not trust Let's Encrypt CA, add this to the Trusted CA

Done!!