To Remind Stephen Hawking

L’astrofisico inglese Stephen Hawking, scomparso all’età di 76 anni, era noto per le osservazioni filosofiche sulla vita oltre che sulla scienza. Ecco alcune delle sue frasi più celebri.

SUL PERCHÉ DELL’ESISTENZA DELL’UNIVERSO – Se riusciremo a trovare la risposta a questa domanda, decreteremo il trionfo definitivo della ragione umana: giacché allora conosceremmo la mente di Dio.

SULLA SUA MALATTIA – Le mie aspettative sono state ridotte a zero quando avevo 21 anni. Da allora, tutto è un bonus. Ho vissuto cinque decadi in più di quanto predetto dai medici. Ho provato a fare buon uso del mio tempo. Poiché ogni giorno può essere l’ultimo, voglio sfruttarne ogni minuto.

SU DIO – Non è necessario invocare l’intervento di Dio per accendere l’interruttore e far partire l’Universo.

SULLA PROSPETTIVA – Ricordatevi di guardare le stelle e non i vostri piedi. Per quanto difficile possa essere la vita, c’è sempre qualcosa che è possibile fare e in cui si può riuscire.

SULLA CELEBRITÀ – Lo svantaggio della mia celebrità è che non posso andare da nessuna parte senza essere riconosciuto. Non serve a nulla indossare occhiali da sole e una parrucca. La sedia a rotelle mi tradisce.

SULLA VANITÀ DEGLI INTELLETTUALI – Le persone che si vantano del loro quoziente intellettivo sono dei perdenti.

SULLA PERFEZIONE – Senza imperfezione, voi e io non esisteremmo.

SUGLI EXTRATERRESTRI – Se gli alieni un giorno venissero a farci visita, penso che il risultato sarebbe simile a quello che è successo quando Cristoforo Colombo è sbarcato in America, un risultato non molto positivo per gli indiani.

SULL’INTELLIGENZA ARTIFICIALE – Le primitive forme di intelligenza artificiale che abbiamo già si sono dimostrate molto utili, ma penso che lo sviluppo di un’intelligenza artificiale completa potrebbe mettere fine alla razza umana.

SULLA MORTE – Vivo con la prospettiva di una morte prematura da 49 anni, non ho paura della morte, ma non ho fretta di morire, ci sono tante cose che voglio fare prima.

Spring Boot OAuth2

Traditional deployment

https://projects.spring.io/spring-security-oauth/docs/oauth2.html

Now we will describe the authorization code flow:

POST /oauth/oauth20/token

Returns an OAuth 2.0 token using HTTP POST.

To request an access token using this grant type, the client must have already obtained the Authorization Code from the authorization server. An Authorization Code is a short-lived token issued to the client application by the authorization server upon successful authentication/authorization of an end-user (resource owner). The client application then uses the authorization code to request an access token from the authorization server.

For detailed examples about the types of access tokens supported, with example for each type of access token, refer to OAuth: Client Authentication with the Platform’s OAuth Provider.

Note: there is a corresponding operation that performs the same action using HTTP GET: GET /oauth/oauth20/token. For information on why you might choose one or the other, see OAuth Operations: GET or POST?

Authorization Roles/Permissions: Anyone can run this operation.

This topic includes the following sections:

HTTP Method

POST

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URL

https://{oauth-provider-url}/oauth/oauth20/token

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Sample Request

The examples below shows token requests in an LDAP scenario, with several different grant types.

Request URL

https://{oauth-provider-url}/oauth/oauth20/token

Sample request headers

Note: In the sample request headers below, the Authorization header consist of the client’s Basic authentication header, as explained in HTTP Basic Authentication. This is one way of sending the authorization credentials. As an alternative, you can send this information in the POST body or, if you are using the GET operation, in the request parameters. For more information, see OAuth: Client Authentication with the Platform’s OAuth Provider.

POST /oauth/oauth20/token HTTP/1.1
Host: http://{oauth-provider-hostname}
Authorization: Basic czZCaGRSa3F0MzpnWDFmQmF0M2JW
Content-Type: application/x-www-form-urlencoded
Accept: application/json

Sample request body: authorization_code grant type

In the sample request body shown below, the client ID and client secret are included. When the Authorization header is included with the request message, as shown above, you don’t need to send the client ID and client secret in the parameters. Send them either in the header or in the parameters. The below is an example of sending these values in the POST request body if the Authorization header was not sent. Line breaks have been added for display purposes.

client_id=acmepaymentscorp-3rCEQzwEHMT9PPvuXcClpe3v
&client_secret=e5868ebb4445fc2ad9f949956c1cb9ddefa0d421
&code=T8Y2h7zvp-tviqe2gQQ_VGQKMizn8jRgxZ74hA
&redirect_uri=http%3A%2F%2Facmepaymentscorp.com%3A9900%2Fui%2Fapps%2Facmepaymentscorp%2F_VWQJeFH76RyfD6M6FRO5Svg%2Fresources%2Fconsole%2Fglobal%2Foauthclientredirect.html%3Fdynamic%3Dtrue
&grant_type=authorization_code
&scope=Scope1

Sample request body: client_credentials grant type (2-legged)

client_id=acmepaymentscorp-3rCEQzwEHMT9PPvuXcClpe3v
&client_secret=e5868ebb4445fc2ad9f949956c1cb9ddefa0d421
&grant_type=client_credentials
&scope=Scope1

Sample request body: Resource Owner Credentials grant type

client_id=atmosphere-3rCEQzwEHMT9PPvuXcClpe3v
&client_secret=e5868ebb4445fc2ad9f949956c1cb9ddefa0d421
&grant_type=password
&scope=Scope1
&username=eng100
&password=password

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Request Headers

For general information on request header values, refer to HTTP Request Headers.

HEADERDESCRIPTION
Acceptapplication/json
Content-Typeapplication/x-www-form-urlencoded
AuthorizationOptional. The Authorization request header authenticates the client with the server.

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Request Parameters

Note: the parameters below are all standard parameters defined in the OAuth 2.0, OpenID Connect, or JSON Web Token (JWT) specifications.

PARAMETERPARM TYPEDATA TYPEREQUIREDDESCRIPTION
grant_typeFormStringRequiredThe OAuth grant type.

If the request is a request for a refresh token, the value must be set to refresh_token.

client_idFormStringOptionalUnique identifier of the client application.

Must be sent; but can be sent as Authorization header.

client_secretFormStringOptionalThe client secret value; this value identifies the client with the provider.

Can be sent as Authorization header. Also, not needed for public client, even if Authorization header is not sent.

refresh_tokenFormStringOptionalRefresh Token grant type only: The refresh token.
scopeFormStringOptionalOAuth 2.0: standard scope parameter. One or more scopes configured in the OAuth provider. Space separator for multiple scopes.

The scope of the access request.

codeFormStringOptionalAuthorization Code grant type only: The authorization code that was previously received by the client application.
redirect_uriFormStringOptionalAuthorization Code grant type only: The redirect URI of the client application, where it received the authorization code.
usernameFormStringOptionalResource Owner Password Credentials only: The resource owner’s username.
passwordFormStringOptionalResource Owner Password Credentials only: The resource owner’s password.
client_assertion_typeFormStringOptionalJWT Bearer Assertion grant type only:

The format of the assertion as identified by the Authorization Server. The value must be set to urn:ietf:params:oauth:client-assertion-type:jwt-bearer.

client_assertionFormStringOptionalJWT Bearer Assertion grant type only: The assertion being used to authenticate the client. Only JWT compact serialization is allowed.
assertionFormStringOptionalJWT Bearer Assertion grant type only: The JWT Bearer Assertion.

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Response

If successful, this operation returns HTTP status code 200, with the access token.

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Sample Response

The sample response below shows successful completion of this operation.

Sample response headers: application/json

HTTP/1.1 200 OK
Content-Type: application/json
Sample response body: application/json

Sample response body #1

{
  "access_token": "SlAV32hkKG",
  "token_type": "Bearer",
  "refresh_token": "8xLOxBtZp8",
  "expires_in": 3600,
  "id_token": "eyJhbGciOiJSUzI1NiIsImtpZCI6IjFlOWdkazcifQ.ewogImlzc
    yI6ICJodHRwOi8vc2VydmVyLmV4YW1wbGUuY29tIiwKICJzdWIiOiAiMjQ4Mjg5
    NzYxMDAxIiwKICJhdWQiOiAiczZCaGRSa3F0MyIsCiAibm9uY2UiOiAibi0wUzZ
    fV3pBMk1qIiwKICJleHAiOiAxMzExMjgxOTcwLAogImlhdCI6IDEzMTEyODA5Nz
    AKfQ.ggW8hZ1EuVLuxNuuIJKX_V8a_OMXzR0EHR9R6jgdqrOOF4daGU96Sr_P6q
    Jp6IcmD3HP99Obi1PRs-cwh3LO-p146waJ8IhehcwL7F09JdijmBqkvPeB2T9CJ
    NqeGpe-gccMg4vfKjkM8FcGvnzZUN4_KSP0aAp1tOJ1zZwgjxqGByKHiOtX7Tpd
    QyHE5lcMiKPXfEIQILVq0pc_E2DzL7emopWoaoZTF_m0_N0YzFC6g6EJbOEoRoS
    K5hoDalrcvRYLSrQAZZKflyuVCyixEoV9GfNQC3_osjzw2PAithfubEEBLuVVk4
    XUVrWOLrLl0nx7RkKU8NXNHq-rvKMzqg"
}

Sample response body: authorization_code grant type

{
  "access_token" : "d50d9fd00acf797ac409d5890fcc76669b727e63",
  "token_type" : "Bearer",
  "expires_in" : 1295998,
  "refresh_token" : "TZzj2yvtWlNP6BvG6UC5UKHXY2Ey6eEo80FSYax6Yv8"
}

Sample response body: Client Credentials grant type (2-legged)

{
  "access_token" : "4484e52dc4744374aced826a4543cd28948816ff",
  "token_type" : "Bearer",
  "expires_in" : 1295999
}

Sample response body: Resource Owner Credentials grant type

{
  "access_token" : "49fad390491a5b547d0f782309b6a5b33f7ac087",
  "token_type" : "Bearer",
  "expires_in" : 1295999,
  "refresh_token" : "USrAgmSf5MJ8N_RLQODa7rZ3zNs1Sj1GkSIsTsb4n-Y"
}

Sample response body: Error scenario

Note: in the example below, the state parameter is included in the error response. This would be the case in any scenario where it was included in the request.

{
  error=invalid_request,
  error_description=Unsupported%20response_type%20value,
  state=af0ifjsldkj
}

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Response Headers

For general information on response header values, refer to HTTP Response Headers.

HEADERDESCRIPTION
Content-Typeapplication/json

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Response Body: Success

NAMETYPEDESCRIPTION
AccessTokenResponseAccessTokenResponseContains information about the response to a request for an OAuth Access Token. Used by the token endpoint.

Response Body: Error Scenario

NAMETYPEDESCRIPTION
AccessTokenErrorResponseAccessTokenErrorResponseContains information about an error response returned by the OAuth Token Endpoint in response to a request for an OAuth 2.0 access token.

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Error Codes/Messages

If the call is unsuccessful an error code/message is returned. One or more examples of possible errors for this operation are shown below.

ITEMVALUE
500An error occurred processing the call.

More information about Enterprise API Platform API error messages.

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How to find process listening over a port

List all tcp ports using netstat -at

netstat -at
 netstat -ltnp 

-p means list all the programs run over the port

List all udp ports using netstat -au

netstat -aup

List only listening ports using netstat -l

netstat -lp

List only the listening UNIX Ports using netstat -lx

netstat -lxp

lsof command (LiSt Open Files) is used to list all open files on a Linux system. To install it on your system, type the command below.

$ sudo yum install lsof	        #RHEL/CentOS 
$ sudo apt install lsof		#Debian/Ubuntu
$ sudo dnf install lsof		#Fedora 22+

To find the process/service listening on a particular port, type (specify the port).

$ lsof -i :80

Create bootable USB stick from ISO in Mac OS X

Convert the ISO to UDRW format

Mac OS X provides all the tools needed to convert the ISO image to UDRW. The following command will convert the ISO image to the UDRW format.

hdiutil convert -format UDRW -o destination_file.img source_file.iso

You will notice that the destination_file.img from the command will create the file destination_file.img.dmg really. This is because the hdiutil program automatically adds the dmg file extension. This is not a problem as the file extension won’t affect the format of the image.

Prepare the USB stick

Check your USB stick and make a backup if there is any important data on it, as the next steps are going to delete everything on it.

To prepare the USb stick we are going to delete all the partitions on the stick and create an empty partition. To do this we need to know the device name of the USB stick. Open a terminal and execute the following command:

$ diskutil list

You will see a list of disks and partitions. The goal is to identify the USB stick in this output. Depending on your system configuration your output might look different from this one. This appears to show 3 physical discs but it does not. The /dev/disk1 is a virtual disk created because of the partition encryption (FileVault 2) I enabled in Mac OS X.

/dev/disk0
#:                       TYPE NAME                    SIZE       IDENTIFIER
0:      GUID_partition_scheme                        *500.1 GB   disk0
1:                        EFI                         209.7 MB   disk0s1
2:          Apple_CoreStorage                         399.5 GB   disk0s2
3:                 Apple_Boot Recovery HD             650.0 MB   disk0s3
5:                 Apple_Boot Boot OS X               134.2 MB   disk0s5
/dev/disk1
#:                       TYPE NAME                    SIZE       IDENTIFIER
0:                  Apple_HFS MacOSX                 *399.2 GB   disk1
/dev/disk2
#:                       TYPE NAME                    SIZE       IDENTIFIER
0:      GUID_partition_scheme                        *2.0 GB     disk2
1:       Microsoft Basic Data UNTITLED 1              2.0 GB     disk2s1

As shown in the output above, the connected USB stick is a small 2.0 GB drive with a FAT partition on it. We are now going to remove this partition in the next step. For the following steps we will need the name of the disk which in this case is “/dev/disk2”.

With the following command the data on the disk (your USB stick) will be deleted!

$ diskutil partitionDisk /dev/disk2 1 "Free Space" "unused" "100%"

With this command the USB stick was re-partitioned to have 1 partition without formatting and 100% of the size of the stick. If you check it again with “diskutil list” you will see the changes already, also the USB stick will no longer be shown in the Finder.

Copy the image to the USB stick

Now we can copy the disk image we created to the USB stick. This is done via the dd(1)command. This command will copy the image to the disk (substitute the appropriate disk name for your USB stick here, as with the re-partitioning command):

$ sudo dd if=destination_file.img.dmg of=/dev/disk2 bs=1m

The dd command does not show any output before it has finished the copy process, so be patient and wait for it to complete.

$ diskutil eject /dev/disk2

To eject the USB stick, use the above command. After this is done, the bootable USB stick is ready to be used.

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