Docker 🐳

Basic Dockerfile commands:

FROM          - Add
MAINTAINER    - Entrypoint
LABEL         - Volume
RUN           - User
CMD           - Workdir
EXPOSE        - On Build
ENV
COPY

Useful commands:

docker build -t image-name path\to\image              - Builds the Image
docker run image-name                                 - Runs the Image
docker image ls                                       - Lists all Images
docker container ls -a                                - Lists all Containers

Container Management

docker run -p 8080:80 SERVICE
               *port

docker container logs -f CONTAINER_ID

docker start OR stop CONTAINER_ID                    - Starts or stops the Container
docker exec -it CONTAINER_ID /bin/bash               - Executes the Container

Image Management

docker pull REGISTRY/IMAGE:TAG                       - Pulls your image from Docker Hub
              *usually your user and image tag

docker push image-name                               - Pushes your image to Docker Hub

---

Creating a recursive DNS server with Docker

docker run -it --name srv-dns -p 53:53/udp -p 53:53/tcp ubuntu        - Port 53 is the default one for DNS [!]

Linux will automatically start after that, so we'll keep going on the container ambient:

apt-get update
apt-get install bind9 bind9utils dnsutils vim -y                      - NVIM is better btw
cd /etc/bind                                                          - Main folder for bind's configuration files

Tip

We'll start our configs through named.conf.options

vim named.conf.options

options {
        // defines the production folder for the server
        directory "/var/cache/bind";

        // will allow any server to make queries on our server
        allow-query{
                any;
        };

        // those are our forwarders
        forwarders {
                8.8.8.8;
        };

        // this lil' bro will add an extra layer of security, the dnssec
        // basically, it'll verify the user's digital signatures
        dnssec-validation auto;

        // this will define which ipv6 interfaces the server's going to hear
        listen-on-v6 { any; };
};

Note

After that config, we can already start bind, we'll use the following commands:

service named status                                                  - Just checking bind's status
service named start                                                   - Will fail if named.config isn't correctly configured

---

Creating and configuring zones

_{And also creating an authoritative DNS server, lmao}

Warning

We'll keep going on the same linux instance, so no need to create a new one if you don't want to.

vim named.conf.local

// here we'll define the name of the domain we're creating
zone "lab.local"{
        type master; // tells that this server has the official copy of this zone

        file "/etc/bind/db.lab.local"; // path to the file that holds the IP registers
};

Then, we'll create our new file, db.lab.local:

vim db.lab.local

$TTL 604800
@       IN      SOA     ns1.lab.local. admin.lab.local. ( ; SOA will define that this bro is the authoritative guy
                        2026020901      ; Serial (file's version)
                        64800           ; Refresh time the slave takes to ask for changes to the master
                        86400           ; Retry (Time the slave waits to ask again in case the master is a jerk and doesn't answer)
                        2419200         ; Expire (Time the slave keeps answering before also shutting down with the master)
                        604800 )        ; Negative Cache TLL (Time for the other servers to decide "This domain doesn't exists")


; Here we're doing the translations (name to IP, IP to name)
@       IN      NS      ns1.lab.local.
ns1     IN      A       172.16.0.2
www     IN      A       172.16.0.100
ftp     IN      A       172.16.0.200

Note

As of now, our Authoritative server is configured!

We'll now test our config with the command named-checkzone lab.local /etc/bind/db.lab.local

service named restart                                  - Just restarting the server
dig @localhost www.lab.local                           - We can change the 'www' to 'ns1' or 'ftp', this will point out to a different address

---

We've made the server translate from name to IP, now we'll do the opposite!

vim named.conf.local

We'll add this to the file:

// in-addr.arpa is the sufix used to tell that this server does the inverse search
zone "0.17.172.in-addr.arpa"{
        type master;

        file "/etc/bind/db.172.17";
};

Let's now create the file db.172.17

vim db.172.17

$TTL    604800
@       IN      SOA     ns1.lab.local. admin.lab.local. (
                        2026021001      ; Serial
                        64800           ; Refresh
                        86400           ; Retry
                        2419200         ; Expire
                        604800          ; Negative Cache
                        )

; This mf will indicate that this is IP to name
@       IN      NS      ns1.lab.local.
2       IN      PTR     ns1.lab.local.
100     IN      PTR     www.lab.local.
200     IN      PTR     ftp.lab.local.

We'll test out our file with named-checkzone 17.172.in-addr-arpa db.172.17

dig @localhost 172.17.0.2                              - Or .100 or .200