• Appendix
    • ➟ DNS
      • ➟ Preliminaries 
> dig learn.mi.hdm-stuttgart.de

; <<>> DiG 9.16.1-Ubuntu <<>> learn.mi.hdm-stuttgart.de
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 63891
...
;; ANSWER SECTION:
learn.mi.hdm-stuttgart.de. 6593	IN	A	141.62.64.28

;; Query time: 0 msec
;; SERVER: 127.0.0.53#53(127.0.0.53) ...
> dig +noall +answer www.hdm-stuttgart.de
www.hdm-stuttgart.de.	3600	IN	A	141.62.1.53
www.hdm-stuttgart.de.	3600	IN	A	141.62.1.59
Record Explanation
A IPV4 Host address
AAAA IPv6 host address
ALIAS Auto resolved alias
CNAME Canonical name for an alias
MX Mail eXchange
NS Name Server
PTR Pointer
SOA Start Of Authority
SRV location of service
TXT Descriptive text 
dig +noall +answer -t NS hdm-stuttgart.de
hdm-stuttgart.de.	3600	IN	NS	iz-net-4.hdm-stuttgart.de.
hdm-stuttgart.de.	3600	IN	NS	dns3.belwue.de.
hdm-stuttgart.de.	3600	IN	NS	iz-net-3.hdm-stuttgart.de.
hdm-stuttgart.de.	3600	IN	NS	dns1.belwue.de.
hdm-stuttgart.de.	3600	IN	NS	iz-net-2.hdm-stuttgart.de.

Exercises are based on the OpenLDAP server implementation.

Related material at http://www.openldap.org.

  • Lightweight Directory Access Protocol

  • Vendor independent

  • IETF standard:

    Clients interact with servers using a directory access protocol

Command Result 
ldapsearch \
  -h localhost ❶ \
  -D "cn=admin,dc=betrayer,dc=com" ❷\
  -w password -x ❸\
  -b "dc=betrayer,dc=com" ❹\
  -s sub ❺ \
  -LLL ❻
 
dn: dc=betrayer,dc=com ❶
objectClass: top
objectClass: dcObject
objectClass: organization
o: Betrayers heaven ❷
dc: betrayer 

dn: cn=admin,dc=betrayer,dc=com ❸
objectClass: simpleSecurityObject
objectClass: organizationalRole
cn: admin ❹
description: LDAP administrator
userPassword:: e1NT...dE53N1E= ❺
Image layer 1
Image layer 2
Image layer 3
Image layer 4
Image layer 5
Image layer 6
Image layer 7
Image layer 8
Image layer 9
Image layer 1
Image layer 2
Image layer 3
Image layer 4
Image layer 5
Image layer 6
dn: uid=clark,ou=finance,dc=betrayer,dc=de ❶
cn: Sandy Clark
homeDirectory: /home/clark
sn: Clark
uid: clark ❷
uidNumber: 21101
givenName: Sandy
loginShell: /bin/bash
mail: clark@betrayer.com ❸
mail: finance@betrayer.com
postOfficeBox: 10G
userPassword: {SSHA}noneOfYourBusiness

  • Structuring LDAP entry data.

  • Categories:

    • Structural

    • Auxiliary

    • Abstract

Abstract classes:

To be extended by other classes

Structural classes:

  • Each entry requires exactly one.

  • Specify the “main” type of object.

  • Must not inherit from auxiliary classes.
Auxiliary classes:

  • Provide non-conflicting supplementary information.

  • Think of (Java™) interfaces.

  • Must not inherit from structural classes.

 
Class                       |   Instance uid=clark,ou=finance,dc=betrayer,dc=de
----------------------------+---------------------------------------------------
inetOrgPerson (structural)  |                   
   sn                       |    sn: Clark
   cn                       |    cn: Sandy Clark
  ...                       |     ▲
                            |     ┃
posixAccount (auxiliary)    |     ┃
  cn                        |   see above ❶
  gidNumber                 |   gidNumber: 23113
  homeDirectory             |   homeDirectory: /home/clark
  uid                       |   uid: clark
  uidNumber                 |   uidNumber: 21101
  userPassword              |   userPassword: {SSHA}noneOfYourBusiness
                          .....
Image layer 1
Image layer 2
Image layer 3
Image layer 4
Image layer 5
Image layer 6

RFC 4520 defines three LDAP search scopes:

RFC 4520 defines predicate based queries using RPN style:

  • (| (cn=k*) (uidNumber < 2000))

  • Anonymous bind: No user credentials.

    Note: This typically provides limited privileges.

  • Simple bind: User's DN + password: 

    DN: uid=clark,ou=finance,dc=betrayer,dc=de
password: 123456789

  • Ldap Data Interchange Format.

  • Importing and exporting LDAP Data.

  • Modifying existing entries (CRUD operations).

  • Pure ASCII. 

dn: uid=clark,ou=finance,dc=betrayer,dc=de
objectClass: posixAccount
objectClass: inetOrgPerson
cn: Sandy Clark
homeDirectory: /home/clark
sn: Clark
uid: clark 
uidNumber: 21101
givenName: Sandy
loginShell: /bin/bash
mail: clark@betrayer.com 
mail: finance@betrayer.com
postOfficeBox: 10G
userPassword: {SSHA}noneOfYourBusiness
Image layer 1
Image layer 2
Image layer 3
Image layer 4
  • Appendix
    • ➟ LDAP
      • ➟ Exercises
        • ➟ Populating your DIT.
An example LDAP Tree
  • Appendix
    • ➟ Apache web server
      • ➟ Preliminaries

Tip

Whenever searching for Apache related documentation always include “2.4” in your query: Configuration file syntax changed considerably with respect to Apache version 2.2.

Image layer 1
Image layer 2
Image layer 3
Image layer 4
Image layer 5

  • One physical host system

  • Serving multiple sites e.g.:

    • https://www.foo.org

    • https://www.second.org

  1. Port based virtual hosting

  2. IP based virtual hosting

  3. Name based virtual hosting

    Typically using Server Name Indication (SNI)

Image layer 1
Image layer 2
Image layer 3
Image layer 4
Image layer 5
Image layer 6
Image layer 7
Image layer 8

  • Host system: One IP per site to serve

  • Pro: TLS handshake without SNI.

    Supporting older clients.

  • Downside:

    • IP address waste

    • Host system NIC configuration required

Image layer 1
Image layer 2
Image layer 3
Image layer 4
Image layer 5
Image layer 6
Image layer 7
Image layer 8

  • Host system: Common IP address

  • Pro

    • No IP address waste

    • No Host system NIC configuration required

  • Cons: Excluding older non SNI supporting clients.

    (Internet Explorer on Windows XP, Android below V. 2.3)

  • SNI allows for eavesdropping requested site's name.

Image layer 1
Image layer 2
Image layer 3
Image layer 4
Image layer 5
Image layer 1
Image layer 2
Image layer 3
Image layer 4
Image layer 5
  • Appendix
    • ➟ File cloud

  • Centralized remote file storage.

  • Proprietary protocols.

  • File Up- and Download.

  • Multi client synchronization.

  • Network file system support.

  • Ubiquitous access.

  • Integrated backup.

  • Versioning.

  • Sharing on user / group level.

  • Secure access, Encryption

  • Consistent availability.

  • Federation support.

  • Local hardware does not scale:

    • Systems interoperability

  • Storage as a service

  • Economy of scale: Cheap hardware, distributed system

  • Google Drive

  • Dropbox

  • OneDrive

  • iCloud Drive

  • Box

  • Amazon Cloud Drive
Lightning integration
  • Appendix
    • ➟ Docker
      • ➟ Introduction

Repository hosting publicly available Docker images:

https://hub.docker.com/explore

  • Appendix
    • ➟ Docker
      • ➟ Introduction
        • ➟ Managing images 
> docker search nextcloud
NAME                       DESCRIPTION      STARS  OFFICIAL   AUTOMATED
nextcloud                  A safe home …    424    [OK]
linuxserver/nextcloud      A Nextcloud …    56
greyltc/nextcloud          Nextcloud: …     34                [OK]
wonderfall/nextcloud       All-in-one …     27                [OK]
rootlogin/nextcloud        Nextcloud …      17                [OK]
lsioarmhf/nextcloud        ARMHF based …    8
ownyourbits/nextcloudpi    NextCloud ARM …  7
...
> docker image pull alpine
Using default tag: latest
latest: Pulling from library/alpine
ff3a5c916c92: Pull complete
Digest: sha256:7df6db5aa61ae9480f52f0b3a06a140ab98d427f86d8d5de0bedab9b8df6b1c0
Status: Downloaded newer image for alpine:latest
> docker image pull wonderfall/nextcloud ❶
Using default tag: latest ❷
latest: Pulling from wonderfall/nextcloud
ff3a5c916c92: Already exists ❸
a542d4c3cffb: Pull complete ❹
83001cc0bea0: Pull complete
41a33c66b2c1: Pull complete
a70bf67726f3: Pull complete
fea90b3d29ac: Pull complete
Digest: sha256:472c5c7...2ca20cca45 ❺
Status: Downloaded newer image for wonderfall/nextcloud:latest
Image layer 1
Image layer 2
Image layer 3
Image layer 4
Image layer 5
Image layer 6
Image layer 7
> docker image inspect dac77467ddcc
[
    {
        "Id": "sha256:dac77467ddccc2287d99558245bd34707...",
        "RepoTags": [
            "nextcloud:13.0.4"
        ],
        "RepoDigests": [
            "nextcloud@sha256:fb3e77f19b21364925e8f02..."
        ],
 ...
> curl 'https://registry.hub.docker.com/v2/repositories/library/nextcloud/tags/'|\
      jq '."results"[]["name"]'  # requires «aptitude install curl jq»
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100 11856    0 11856    0     0  11856      0 --:--:-- --:--:-- --:--:-- 20371
"fpm"
"production"
"stable"
"latest"
"13"
"13.0"
"13.0.2"
"production-apache"
"stable-apache"
"apache"
> docker image pull nextcloud:13.0.4
13.0.4: Pulling from library/nextcloud
3d77ce4481b1: Pull complete
32bfdb6043a8: Pull complete
028453741593: Pull complete
f93d7bd342a3: Pull complete
4a2fac611953: Pull complete
87fdfc7d0f94: Pull complete
Digest: sha256:fb3e77f19b21364925e8f02d6e5ad3a1 ...
Status: Downloaded newer image for nextcloud:13.0.4
> docker image ls
REPOSITORY            TAG      IMAGE ID       CREATED        SIZE
nextcloud             13.0.4   dac77467ddcc   3 days ago     544MB
wonderfall/nextcloud  latest   57e1fb51b334   2 months ago   328MB
alpine                latest   3fd9065eaf02   4 months ago   4.15MB
> docker image pull nextcloud
Using default tag: latest
latest: Pulling from library/nextcloud ❶
Digest: sha256:fb3e77f19b21364925e8f02d6e5ad3a1 ... ❷
Status: Downloaded newer image for nextcloud:latest
> docker image ls 
REPOSITORY          TAG                 IMAGE ID            CREATED             SIZE
nextcloud           13.0.4              dac77467ddcc        4 days ago          544MB
nextcloud           latest              dac77467ddcc        4 days ago          544MB
...
<dependency>
  <groupId>junit</groupId>           <!-- wonderfall -->
  <artifactId>junit</artifactId>     <!-- nextcloud -->
  <version>4.12</version>            <!-- 13.0.4 -->
</dependency>
> docker image rm nextcloud:latest
Untagged: nextcloud:latest

> docker image ls
REPOSITORY          TAG                 IMAGE ID            CREATED             SIZE
nextcloud           13.0.4              dac77467ddcc        4 days ago          544MB
...
> docker image rm nextcloud:13.0.2
Untagged: nextcloud:latest
Untagged: nextcloud@sha256:c693921e69cb89cd0bee7c014280159df647e5ba87f54c895650156d973df035
Deleted: sha256:10ae267ddcf25bfe5cc059685d3d005bcfe7229b44c3a6f93e0a07795d33b5b2
Deleted: sha256:1c271f4f2f19a222cd116c771b02294c5dd596fa8a0366559061f83a0de8de3f
...
Deleted: sha256:2c833f307fd8f18a378b71d3c43c575fabdb88955a2198662938ac2a08a99928
  • Appendix
    • ➟ Docker
      • ➟ Introduction
        • ➟ Running container 
> docker run -d -p 8080:80 --name nc13 nextcloud
517e3dba488763eb615f2c68d417e1b7fb3a9ce5bb4a5ffc346dcb86c00d13d2
> docker ps -a  # show stopped containers as well
CONTAINER ID  IMAGE      COMMAND                ... PORTS                 NAMES
517e3dba4887  nextcloud  "/entrypoint.sh apac…" ... 0.0.0.0:8080->80/tcp  nc13
> docker exec -it nextcloud_db_1 /bin/bash
# ls -al
total 84
drwxr-xr-x   1 root root 4096 Jun 20 09:28 .
drwxr-xr-x   1 root root 4096 Jun 20 09:28 ..
-rwxr-xr-x   1 root root    0 Jun 20 09:28 .dockerenv
drwxr-xr-x   1 root root 4096 May 25 20:20 bin
drwxr-xr-x   2 root root 4096 Nov 19  2017 boot
drwxr-xr-x   5 root root  340 Jun 20 09:28 dev
drwxr-xr-x   2 root root 4096 Apr 30 15:37 docker-entrypoint-initdb.d
lrwxrwxrwx   1 root root   34 May 25 20:20 docker-entrypoint.sh -> usr/local/bin/docker-entrypoint.sh
...
> docker rm nc13
nc13
> docker ps -a
CONTAINER ID   IMAGE       COMMAND             CREATED      STATUS                   ... NAMES
  • Appendix
    • ➟ Docker
      • ➟ Introduction
        • ➟ Volumes 
> docker volume ls
DRIVER              VOLUME NAME
local               nextcloud_db
local               nextcloud_nextcloud
 
# ls -al /var/lib/docker/volumes
total 40
drwx------  4 root root  4096 Jun 20 11:13 .
drwx--x--x 14 root root  4096 Jun 20 09:40 ..
-rw-------  1 root root 32768 Jun 20 11:13 metadata.db
drwxr-xr-x  3 root root  4096 Jun 20 11:13 nextcloud_db
drwxr-xr-x  3 root root  4096 Jun 20 11:13 nextcloud_nextcloud
 
> docker volume ls -f dangling=true
DRIVER              VOLUME NAME
local               nextcloud_db
local               nextcloud_nextcloud
> docker volume rm nextcloud_db nextcloud_nextcloud
nextcloud_db
nextcloud_nextcloud
  1. Airlines, airports and flights
  2. Creating a Hibernate JPA project
  3. Adding keys and AUTO_INCREMENT
  4. Advocating simple key definitions