Author Image Posted By : Graham Carmichael 10 Dec
Understanding the Cloud (Draft)

So what is the cloud? In most basic terms the cloud is server resources hosted in a data centre owned and operated by someone else.

So what does that mean. It means you don’t have to have your own datacenter, which is an area designed specifically to keep servers running. Space, power and air conditioning. These are expensive if done properly. It also mean that IT resource, by that I mean people, are not needed to maintain and repair the servers and the supporting infrastructure.

The up sides. If you want to use software hosted by other companies, software as a service (SaaS), you hand over your subscription fee and off you go. Software could be anything from your supply chain to a word processor. Generally all you need is a web browser and an internet connection. If you want storage such as dropbox, you need a computer with the dropbox client installed and an internet connection. You could even run your Windows Servers in the cloud.

The Down Sides. You are now very reliant on your internet service provider and all internet service providers between you and the other datacenter. You are reliant on the speed of that internet connection and all links between you and the other datacenter. You are trusting others to keep your data safe and secure and yes these systems are connected directly to the internet. You are trusting that these companies are not going to go bust and take your data with them. Yes it has happened.

 

Author Image Posted By : Graham Carmichael 7 Nov
Flexible Single Master Operation Roles (FSMO)

Flexible Single Master Operation Roles (FSMO)

Active Directory has five special roles which are vital for the smooth running of AD as a multimaster system. Some functions of AD require there is an authoritative master to which all Domain Controllers can refer to. These roles are installed automatically and there is normally very little reason to move them, however if you de-commission a DC and DCPROMO fails to run correctly or have a catastrophic failure of a DC you will need to know about these roles to recover or transfer them to another DC.

The forest wide roles must appear once per forest, the domain wide roles must appear once per domain.

The Roles

There are five FSMO roles, two per forest, three in every Domain. A brief summary of the role is below.

Forest Wide Roles:

  • Schema Master

The schema is shared between every Tree and Domain in a forest and must be consistent between all objects. The schema master controls all updates and modifications to the schema.

  • Domain Naming

When a new Domain is added to a forest the name must be unique within the forest. The Domain naming master must be available when adding or removing a Domain in a forest.

Domain Wide Roles:

  • Relative ID (RID) Master

Allocates RIDs to DCs within a Domain. When an object such as a user, group or computer is created in AD it is given a SID. The SID consists of a Domain SID (which is the same for all SIDs created in the domain) and a RID which is unique to the Domain.

When moving objects between domains you must start the move on the DC which is the RID master of the domain that currently holds the object.

  • PDC Emulator

The PDC emulator acts as a Windows NT PDC for backwards compatibility, it can process updates to a BDC.

It is also responsible for time synchronising within a domain.

It is also the password master (for want of a better term) for a domain. Any password change is replicated to the PDC emulator as soon as is practical. If a logon request fails due to a bad password the logon request is passed to the PDC emulator to check the password before rejecting the login request.

  • Infrastructure Master

The infrastructure master is responsible for updating references from objects in its domain to objects in other domains. The global catalogue is used to compare data as it receives regular updates for all objects in all domains.

Any change to user-group references are updated by the infrastructure master. For example if you rename or move a group member and the member is in a different domain from the group the group will temporarily appear not to contain that member.

Important Note :

Unless there is only one DC in a domain the Infrastructure role should not be on the DC that is hosting the global catalogue. If they are on the same server the infrastructure master will not function, it will never find data that is out of date and so will never replicate changes to other DCs in a domain.

If all DCs in a domain also host a global catalogue then it does not matter which DC has the infrastructure master role as all DCs will be up to date due to the global catalogue.

Viewing and Transferring Roles

The roles can be viewed and transferred in the GUI or from the command line.

Gui View

Schema Master

To view the schema you must first register the schema master dll with Windows. To do this enter the following in the RUN dialog of the start menu.

regsvr32 schmmgmt.dll

Once you have done this the schema master mmc snap-in will be available.

Active Directory Domains and Trusts

The Domain naming master can be viewed and transferred from here.

Active Directory User and Computers

The RID, PDC emulator and Infrastructure master roles can be viewed and transferred from here.

NTDSUTIL

NTDSUTIL provides FSMO maintenance and the option to seize a role (covered in the FSMO Role Failure section below).

To transfer a role using ntdsutil use the example below as a template for all the roles.

  • Open a command prompt
  • Enter in ntdsutil
  • At the ntdsutil command prompt enter in roles
  • At the fsmo maintenance prompt enter in connection
  • At the server connections prompt enter in connect to domancontrollername
  • At the server connections prompt enter in quit
  • At the fsmo maintenance prompt enter in transfer schema master
  • Quit from the console

FSMO Role Failure

Some of the operations master roles are essential for AD functionality, others can be unavailable for a while before their absence will be noticed. Normally it is not the failure of the role, but rather the failure of the DC on which the role is running.

If a DC fails which is a role holder you can seize the role on another DC, but you should always try and transfer the role first.

Before seizing a role you need to asses the duration of the outage of the DC which is holding the role. If it is likely to be a short outage due to a temporary power or network issue then you would probably want to wait rather than seize the role.

Schema Master Failure

In most cases the loss of the schema master will not affect network users and only affect Admins if modifications to the schema are required. You should however only seize this role when the failure of the existing holder is considered permanent.

Note: A DC whose schema master role has been seized should never be brought back online

Domain Naming Master Failure

Temporary loss of this role holder will not be noticeable to network users. Domain Admins will only notice the loss if they try and add or remove a domain in the forest. You should however only seize this role when the failure of the existing holder is considered permanent.

Note: A DC whose schema master role has been seized should never be brought back online

RID Master Failure

Temporary loss of this role holder will not be noticeable to network users. Domain Admins will only notice the loss if a domain they are creating objects in runs out of relative IDS (RIDs). You should however only seize this role when the failure of the existing holder is considered permanent.

Note: A DC whose schema master role has been seized should never be brought back online

PDC Emulator Master Failure

Network users will notice the loss of the PDC emulator. If the DC with this role fails you may need to immediately seize this role. Only pre Windows 2000 clients and NT4 BDCs will be affected.

If you seize the role and return the original DC to the network you can transfer the role back.

Infrastructure Master Failure

Temporary loss of this role holder will not be noticeable to network users. Administrators will not notice the role loss unless they are or have recently moved or renamed large numbers of accounts.

If you are required to seize the role do not seize it to a DC which is a global catalogue server unless all DCs are global catalogue servers.

If you seize the role and return the original DC to the network you can transfer the role back.

Author Image Posted By : Graham Carmichael 29 Oct
Ansible code to update all Raspberry Pi

The following code will one by one update your raspberry Pis and then reboot them.


---
- hosts: all
remote_user: pi
serial: 1

tasks:
– name: Update all packages
apt:
upgrade: dist
update_cache: yes
become: yes
register: updated

– name: Reboot Machine if updated
command: shutdown -r +1
async: 1
poll: 0
ignore_errors: true
become: yes
when: updated.changed

– name: Wait for Machine to come back online
local_action: wait_for
host={{ inventory_hostname }}
port=22
state=started
delay=65
when: updated.changed
~

Author Image Posted By : Graham Carmichael 12 Oct
Line Support

The definition tends to vary from company, sector etc :

1st Line Support – Helpdesk (Job titles such as Helpdesk Analyst, First Line Support, Call Logger)
Typically involves resolving calls over the phone in a service desk environment and may escalate to 2nd line support.

2nd Line Support – Desktop Support (Job titles such as IT Technician, PC Engineer, Desktop Support Analyst)
Typically involves onsite desktop support of all workstations, printers, scanners etc

3rd Line Support – Network Support (Job titles such as Network Admin, Network Manager, Server Engineer)

Typically involves onsite support of all servers and dedicated to maintenance of network related issues.

Author Image Posted By : Graham Carmichael 11 Apr
Quote of the week

Ex-cabinet minister Liam Fox called it another “dodgy dossier” full of “opinions, assertions and suppositions” and in a reference to European Commission president Jean Claude Juncker added: “It’s bad enough that we get junk mail but to have Juncker mail sent to us with our own taxes is the final straw.”

Author Image Posted By : Graham Carmichael 29 Mar
When does 5000 = 950

When you are talking about a UltraFire 18650 5000mAh battery.

ultrafire-18650-3-7v-5000mah-li-ion-rechargeable

Yes, sold as a 5000mAh battery it’s really less than 1/5 of the advertised value, about 950mAh by my measurements. Beware what you buy. Stick to the well known names.

Author Image Posted By : Graham Carmichael 26 Mar
The IQ Curve

Just because I can.

100 is the average so that means 50% of people must be at 100 or below.

iq_bell_curve

 

IQ Percentage of the population with this IQ Interpretation
> 130 2.1 Very gifted
121-130 6.4 Gifted
111-120 15.7 Above average intelligence
90-110 51.6 Average intelligence
80-89 15.7 Below average intelligence
70-79 6.4 Cognitively impaired