@@ -93,7 +93,12 @@ An **IPv4** is composed of 4 digits ranging from 0 to 255 separated by `.` , whi
## IPv6
An **IPv6** is composed of 8 groups of 4 digits long number separated by `:`. The numbers are in hexadecimal format (number of base 16, randing from 0 to 9 and A to F). Compared to **IPv4**, **IPv6** allows for 2^128 = 340,282,366,920,938,463,463,374,607,431,768,211,456 addresses (approximately 3.4×10^38). For example, an IP address is: *2001:0db8:0000:0000:0000:ff00:0042:8329*
An **IPv6** is composed of 8 groups of 4 digits long number separated by `:`.
The numbers are in hexadecimal format (number of base 16, randing from 0 to 9 and A to F).
Compared to **IPv4**, **IPv6** allows for 2^128 = 340,282,366,920,938,463,463,374,607,431,768,211,456 addresses (approximately 3.4×10^38).
For example, an IP address is: **2001:0db8:0000:0000:0000:ff00:0042:8329**
To display your VM IP addresses you can use the following command: `ip address show`
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@@ -107,14 +112,14 @@ Instead of using IP addresses in your everyday life, you often use the domain na
## Transmission Control Protocol (**TCP**)
The **Transmission Control Protocol** (**TCP**) is one of the main [protocols](https://en.wikipedia.org/wiki/Communications_protocol) of the [Internet protocol suite](https://en.wikipedia.org/wiki/Internet_protocol_suite). TCP provide, reliable, ordered, and error-checked delivery of a stream of data between applications running on hosts communincating over an IP network.
The **Transmission Control Protocol** (**TCP**) is one of the main [protocols](https://en.wikipedia.org/wiki/Communications_protocol) of the [Internet protocol suite](https://en.wikipedia.org/wiki/Internet_protocol_suite). TCP provide, reliable, ordered, and error-checked delivery of a stream of data between applications running on hosts communicating over an IP network.
- data arrives in-order
- data has minimal error (i.e., correctness)
- duplicate data is discarded
- lost or discarded packets are resent
- includes traffic congestion control
- Heavtweight (no ordering of messages, no tracking connections, etc. It is a very simple transport layer designed on top of IP)
- Heavyweight (no ordering of messages, no tracking connections, etc. It is a very simple transport layer designed on top of IP)
## **User Datagram Protocol** (**UDP**)
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@@ -128,9 +133,9 @@ UDP uses a simple [connectionless communication](https://en.wikipedia.org/wiki/C
## Port
Higher, communication protocols like TCP and UDP, also define **port**. A **port** is a communication endpoint. When software wants to communicate overt TCP or UDP it will do so using a specific **port**. Each system has **port** numbers ranging from 0 to 65535. **Port** numbered from 0 through 1023 are system **ports** used by well-known processes (you need specific rights to use them).
Higher, communication protocols like TCP and UDP, also define **port**. A **port** is a communication endpoint. When software wants to communicate overt TCP or UDP it will do so using a specific **port**. Each system has **port** numbers ranging from **0** to **65535**. **Port** numbered from **0** through **1023** are system **ports** used by well-known processes (you need specific rights to use them).
| 80 | [Hypertext Transfer Protocol](https://en.wikipedia.org/wiki/Hypertext_Transfer_Protocol) (HTTP) used in the [World Wide Web](https://en.wikipedia.org/wiki/World_Wide_Web) |
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@@ -154,11 +159,11 @@ Nowadays, **ports** provide multiplexing, which means that multiple service or c
# SSH
There are numerous other protocols ([RTP](https://en.wikipedia.org/wiki/Real-time_Transport_Protocol) for example). But most of them run over the TCP and UDP protocols. **SSH** or **Secure Shell** is one of them. SSH is a [cryptographic](https://en.wikipedia.org/wiki/Cryptography) [network protocol](https://en.wikipedia.org/wiki/Network_protocol) for operating network services securely over an unsecured network.
There are numerous other protocols ([RTP](https://en.wikipedia.org/wiki/Real-time_Transport_Protocol) for example). But most of them run over the **TCP** and **UDP** protocols. **SSH** or **Secure Shell** is one of them. **SSH** is a [cryptographic](https://en.wikipedia.org/wiki/Cryptography) [network protocol](https://en.wikipedia.org/wiki/Network_protocol) for operating network services securely over an unsecured network.
SSH use a client-server architecture, you use an SSH client to connect to an SSH server. By default most Linux distribution don’t comes with an SSH server installed. For the IFB, SSH connection is the default way to connect to your VMs, so you should have an SSH sever up and running.
**SSH** use a client-server architecture, you use an **SSH client** to connect to an **SSH server**. By default most Linux distribution don’t come with an **SSH server** installed. For the IFB, **SSH** connection is the default way to connect to your VMs, so you should have an **SSH** sever running.
SSH uses [Public-key cryptography (or asymmetric cryptography](https://en.wikipedia.org/wiki/Public-key_cryptography)), to secure its communications.
## Public-key cryptography
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@@ -220,9 +225,10 @@ docker run -it --volume /:/root/chroot alpine sh -c "chroot /root/chroot /bin/ba
Using the `sudo` command edit the configuration file to set **PasswordAuthentication** to **yes** and add the following lines:
**AllowUsers etudiant student**
**PermitRootLogin no**
```
AllowUsers etudiant student
PermitRootLogin no
```
The `sshd` (SSH Daemon) process in launched and managed by `systemd`. You can manage `systemd` service with the `systemctl` command. Try this command without any arguments. You can search for `sshd` by typing `/sshd` and pressing `enter`. You can leave the `systemctl` view by pressing `q`.
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@@ -263,7 +269,7 @@ ssh login@IP_adress
Use this command to connect to another student VM.
On the first connection, `ssh` ask you to accept the public key of the server (key fingerprint). With that in the future if someone try to fool you by impersonating the ssh server, he won’t be able to do it without the corresponding private key.
On the first connection, `ssh` ask you to accept the public key of the server (key fingerprint). With that in the future if someone tries to fool you by impersonating the ssh server, he won’t be able to do it without the corresponding private key.
You can close the connection by pressing `ctrl` + `d` or with the command `exit`.
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@@ -315,7 +321,7 @@ Sometime, you want to do other things than executing commands on a remove comput
## scp
The `scp` command comes with the `ssh` client installation you can use it to transfer file from your computer to the ssh sever:
The `scp` command comes with the `ssh` client installation you can use it to transfer files from your computer to the ssh sever:
