Bootleg bot

Networking

🟣 = a device (server/laptop/phone/...)
🟡 = a network

We will go through the following commands from 🟣 sergio.

So the first step is to log into 🟣 sergio:

ssh sergio

To which networks is 🟣 sergio connected right now?

ip a

To which networks is 🟣 the bootleg library connected right now?

1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP group default qlen 1000
    link/ether dc:a6:32:54:34:1c brd ff:ff:ff:ff:ff:ff
    inet 145.24.153.55/23 brd 145.24.153.255 scope global dynamic noprefixroute eth0
       valid_lft 207029sec preferred_lft 174629sec
    inet6 fe80::9e59:5f86:ee6:e86d/64 scope link 
       valid_lft forever preferred_lft forever
3: wlan0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
    link/ether dc:a6:32:54:34:1e brd ff:ff:ff:ff:ff:ff
    inet 10.9.8.1/24 brd 10.9.8.255 scope global noprefixroute wlan0
       valid_lft forever preferred_lft forever
    inet6 fe80::9724:36ee:d995:558e/64 scope link 
       valid_lft forever preferred_lft forever
4: hub: <POINTOPOINT,MULTICAST,NOARP,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UNKNOWN group default qlen 500
    link/none 
    inet 10.0.0.103/24 scope global hub
       valid_lft forever preferred_lft forever
    inet6 fe80::6fce:6106:9b56:33db/64 scope link stable-privacy 
       valid_lft forever preferred_lft forever

Is 🟣 sergio part of the same network as 🟣 the bootleg library is?

...

How can we check if we can communicate with 🟣 the bootleg library through this network?

ping ip-address 

Let's first check 🟡 the XPUB HUB (see all HUB servers listed here)

ping 10.0.0.103

Who else is on 🟡 the HUB network right now?

nmap 10.0.0.*

And who else is on 🟡 eduroam right now? (in the same subnet)

nmap 145.24.152.*

Can we reach 🟣 the bootleg library through 🟡 eduroam?

ping 145.24.153.55

We can make such a mapping because we are part of the same LAN network.

LAN = local area network

Let's take a short side step.

We want to make a zulip bot. Which network do we use everyday to connect to 🟣 the XPUB zulip server?

ping zulip.xpub.nl
<check your ip address from your device>

How does such a zulip connection travel?

traceroute zulip.xpub.nl

We can trace this route because all the "hops" are done on 🟡 the public internet (the WAN).

WAN = wider area network, aka the internet

So to summarize, these devices are part of the following networks:

🟣 bootleg library: 🟡 10.0.0.103 + 🟡 145.24.153.55
🟣 sergio: 
🟣 your laptop: 
🟣 XPUB zulip server: 

With an important footnote: we're not sure if it was intentional to have 🟣 the bootleg library on 🟡 eduroam. So let's keep in mind that we will most likely loose this connection.

Which 🟣 device can we use to run a bot that connects the 🟣 XPUB zulip server to 🟣 the bootleg library (on 🟡 the HUB), keeping in mind that the whole goal of this is to connect to 🟣 the bootleg library from 🟡 the WAN?

...

How can we connect 🟣 our device (on 🟡 WAN) to 🟣 sergio (on 🟡 eduroam + 🟡 HUB) to connect to 🟣 the bootleg library (on 🟡 eduroam + 🟡 HUB)?

in many ways... 

But which option will we focus on today?

SSH tunnelling!

SSH tunnelling

https://ittavern.com/visual-guide-to-ssh-tunneling-and-port-forwarding/

(After having written this... I think we need to simplify this step and only use the xpub user on sergio...)

From your device, ssh into the bootleg library using a SSH tunnel:

ssh -J sergio pi@10.0.0.103

From $ man ssh:

-J destination
 
Connect to the target host by first making a ssh connection to the jump host described by destination and then establishing a TCP forwarding to the ultimate destination from there. Multiple jump hops may be specified separated by comma characters. This is a shortcut to specify a ProxyJump configuration directive.

Install your SSH key on the bootleg library

If you get a "publickey denied" error, you need to install a SSH key of your user on sergio to the bootleg library.

First generate a SSH key.

ssh-keygen -t ed25519

Find the public key:

cd .ssh
cat id_ed25519.pub

Copy the output.

Log in to the bootleg library with the xpub user on sergio:

ssh sergio
sudo su - xpub
sudo pi@10.0.0.103

This works, and without password, because the SSH keys of xpub@sergio are already installed at pi@bootleglibrary.

Move to the .ssh folder:

cd .ssh

Open the authorized keys file:

nano authorized_keys

Paste your public key!

Now try the tunnel again.