adds solution for ftp excersise
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# The FTP challenge
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## Getting the file
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The first step to solving this exersise is to download the CSV file to your Raspberry.
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For those wondering what on earth a CSV file is I invite you to a detailed [read](https://en.wikipedia.org/wiki/Comma-separated_values) but to make a long story short it stands for *comma separated values* and is one of the most basic ways to structure data.
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You can use Libreoffice calc to open it and you'll quickly understand how it works.
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Now, to get the file onto our Raspberry PI we need to download it from the webserver.
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One way would be to use the `wget` program to do so.
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We know *where* the server is by it's IP address, plus we also know the *filename*.
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Putting these two together we can construct the following line.
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```bash
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wget 172.30.6.96/accounts.csv
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```
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This will download the file to the directory we're in and will save it as `accounts.csv`.
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You can change the output filename it you want, just have a look at the `wget` options via `wget --help` or our trusty `man wget`.
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## Extracting the data we need
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A quick `cat accounts.csv` gives us the following output:
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```bash
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EMAIL,LASTNAME,FIRSTNAME,MATRIX,GITEA,TEAM
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1h.lust.hugo@gmail.com,Lust,Hugo,@hugo_lust:86thumbs.net,https://gitea.86thumbs.net/Hugo,red
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ticus@kraland.net,krstev,vladimir,@vl4dd:86thumbs.net,https://gitea.86thumbs.net/vl4dd,blue
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adamd@outlook.be,Adam,David,@adamd73:matrix.org,https://gitea.86thumbs.net/adamd,red
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nicohawai@gmail.com,Perez,Nicolas,@hawai:86thumbs.net,https://gitea.86thumbs.net/Hawai,blue
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nicolas.wattripont@gmail.com,Wattripont,Nicolas,@wawa142:86thumbs.net,https://gitea.86thumbs.net/wawa142,red
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laurentdelvigne@hotmail.com,Delvigne,Laurent,@ldelvigne:86thumbs.net,https://gitea.86thumbs.net/ldelvigne,blue
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sselcukaslan@gmail.com,Aslan,Selçuk,@slck:86thumbs.net,https://gitea.86thumbs.net/selcuk,blue
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Sarah24886@hotmail.com,Rmiki,Sarah,@sarahrm95:matrix.org,https://gitea.86thumbs.net/sarahrm95,blue
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knoppixs@hotmail.com,Abbamoulay,Abdellah,@knoppixs:86thumbs.net,https://gitea.86thumbs.net/Abdellah,red
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JonathanDechief@hotmail.com,Dechief,Jonathan,@elewene:matrix.org,https://gitea.86thumbs.net/Elewene,red
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51207@etu.he2b.be,,Aliou,@aliou:86thumbs.net,https://gitea.86thumbs.net/aliou,blue
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```
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### The $USERNAME
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To extract the `$USERNAME` we're interested in the fourth collumn which has the MATRIX login handle.
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We can extract only this collumn by using `cut` with `,` as a delimiter.
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```bash
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cat accounts.csv | cut -d "," -f 4
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```
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This leaves us with only the MATRIX login handles which is a good start but there is still a bit too much information .
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We need to drop the first line, which is the *header* of the CSV file, plus crop between the `@` and the `:`.
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These two operations can be done is multiple ways but I suggest this modification.
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It is not the most elegant solution but it uses only tools you have used this far.
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The `tail` command drops the *header* line, and the two `cut` commands trim the username to just what we need.
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```bash
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cat accounts.csv | cut -d "," -f 4 | tail -n +2 | cut -d ":" -f 1 | cut -d "@" -f 2
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```
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Done!
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We have all the usernames we need.
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We can save this to a file by redirecting the STDOUT to a file with the following command.
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```bash
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cat accounts.csv | cut -d "," -f 4 | tail -n +2 | cut -d ":" -f 1 | cut -d "@" -f 2 > usernames.list
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```
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### The $PASSWORD
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To extract the password we need to combine two field from the CSV file.
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A *really* good command line program to accieve this is `awk`.
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Don't forget the man pages!
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```bash
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cat accounts.csv | awk -F "," '{print $2 $3}' | tail -n +2
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```
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If you feel like making the password complexer, you can try to add in extra data into the `awk` command, or even append random numbers to the end.
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```bash
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cat accounts.csv | awk -F "," '{print $2 "_helloworld_" $3}' | tail -n +2
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```
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We can now save these passwords to a file in the same way as before.
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### The $GROUP
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This is an *easy* one because it requires no real modification of the field.
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```bash
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cat accounts.csv | tail -n +2 | cut -d "," -f 6 > groups.list
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```
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## Using this information to create accounts
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We now have command that extracts the information we need, plus three separate files that contain all the information.
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This is a good moment to try and write a very simple script.
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I'll first try to do it without a loop but you'll quickly see it's a *lot* easier with a loop in there.
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Remember that `$1` represents the first argument on the command line so that when calling our script with `./script.sh 3` we'll get the username, password and group for the third user.
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A combination of `head | tail` is a [classic](https://stackoverflow.com/questions/6022384/bash-tool-to-get-nth-line-from-a-file) way of selection only one file from a file.
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Last but not least, don't forget to add execution permissions to this script with `chmod`.
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```bash
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#!/bin/bash
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LINE=$1
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head -$1 usernames.list | tail -1
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head -$1 passwords.list | tail -1
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head -$1 groups.list | tail -1
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```
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We can then *copy/paste* this information to create the following line.
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We'll be prompted to paste in the proper information.
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```bash
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sudo adduser $USERNAME
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```
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Needless to say this is a labour intensive operation that we can automate with a mini script.
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### Putting it together as a script
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Brace yourselves a bit but I promise it's worth it!
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The only thing we have not seen is how to save the output of a command into a variable.
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This can be done with the `$(...)` syntax.
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I know it looks a bit cryptic but an example speaks more than words.
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```bash
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NOW=$(date)
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echo $NOW
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```
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With this in mind, the following code should make sense.
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We're doing the exact same thing but saving the output of each command into a variable.
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At the last line we *use* the variables to create a message.
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```bash
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#!/bin/bash
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LINE=$1
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USERNAME=$(head -$1 usernames.list | tail -1)
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PASSWORD=$(head -$1 passwords.list | tail -1)
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GROUP=$(head -$1 groups.list | tail -1)
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echo "user: $USERNAME password: $PASSWORD group: $GROUP"
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```
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This just output's all information onto one line, but why not *use* this information to actually create the accounts?
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A counterpart to the `adduser` program you're used to using, there is also `useradd` which is better suited for scripting purposes.
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By default `useradd` is very *barebones* and does not create a home directory for the user but a quick look at the `man useradd` pages tells us we can use the `-m` flag to do so.
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This tells us the the command `useradd $USERNAME -m` will create a user for us with his/her own home directory.
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A [google search](https://linux.die.net/man/8/chpasswd) pointed me to `chpasswd` to set passwords from within a script.
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The line to set the password will be `echo $USERNAME:$PASSWORD | chpasswd`.
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This gives us the following script.
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```bash
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#!/bin/bash
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LINE=$1
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USERNAME=$(head -$1 usernames.list | tail -1)
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PASSWORD=$(head -$1 passwords.list | tail -1)
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GROUP=$(head -$1 groups.list | tail -1)
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echo "adding user: $USERNAME"
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useradd $USERNAME -m
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echo "setting password: $PASSWORD for $USERNAME"
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echo $USERNAME:$PASSWORD | chpasswd
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```
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You probably noticed I did not add the users to their *red/blue* groups.
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We can add them on the `useradd` line with the `-G` flag but it would fail if the group does not exist yet.
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The `groupadd` command will add a group to the system and if we add the `-f` flag to it will do so without complaining if the group already exists.
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This way we can just execute that line each time without worrying wether the group exists or not.
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```bash
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#!/bin/bash
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LINE=$1
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USERNAME=$(head -$1 usernames.list | tail -1)
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PASSWORD=$(head -$1 passwords.list | tail -1)
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GROUP=$(head -$1 groups.list | tail -1)
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echo "making sure $GROUP exists..."
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groupadd -f $GROUP
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echo "adding user: $USERNAME"
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useradd $USERNAME -m -G $GROUP
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echo "setting password: $PASSWORD for $USERNAME"
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echo $USERNAME:$PASSWORD | chpasswd
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```
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Those who switched to the newly created user noticed that the shell is *very* basic one.
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You can find out which shell these new accounts use by looking at the `/etc/passwd` file.
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There are multiple ways to sort this problem but a look at the `man useradd` pages tells us we can use the `-s` flag to set the shell we want for the user.
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We probably want to use `/bin/bash` for this option!
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```bash
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#!/bin/bash
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LINE=$1
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USERNAME=$(head -$1 usernames.list | tail -1)
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PASSWORD=$(head -$1 passwords.list | tail -1)
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GROUP=$(head -$1 groups.list | tail -1)
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echo "making sure $GROUP exists..."
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groupadd -f $GROUP
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echo "adding user: $USERNAME"
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useradd $USERNAME -m -G $GROUP -s "/bin/bash"
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echo "setting password: $PASSWORD for $USERNAME"
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echo $USERNAME:$PASSWORD | chpasswd
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echo "adding $USERNAME to $GROUP"
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```
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This is getting pretty close to perfect!
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We can now run through all of the lines of the file one by one and automatically create the proper user, password and group combinations.
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To know how many accounts we have to create we can use `wc -l accounts.csv` and then just run the script, incrementing the number each time.
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```bash
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sudo ./script.sh 1
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sudo ./script.sh 2
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sudo ./script.sh 3
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echo "etc..."
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```
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### Taking it further as an extra challenge
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If we want to automate the entire thing we'll need a loop to *loop through* every line in the `accounts.csv` file.
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Bash loops are for a further class but I'll leave you with this quick example for those who feel like messing around.
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Remember the *oneliners* we constructed at the beginning to extract the relevant information from the line!
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Don't worry if this looks to complicated at the moment, we'll do this exersise again when we're looking into [bash scripting](https://ryanstutorials.net/bash-scripting-tutorial/).
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```bash
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#!/bin/bash
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FILE=$1
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LINES=$(cat $1)
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for LINE in $LINES;
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do
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echo $LINE
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done
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```
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## Setting up the fileserver
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### FTP
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A quick [google](https://likegeeks.com/ftp-server-linux/) tells us `vsftpd` is a popular *FileTransferProtocol* server.
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As expected you can find it in the main Debian repositories.
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You know how to install it by now!
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```bash
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sudo apt search vsftpd
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```
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To know *where* to configure the server we can look at the `man vsftpd` pages.
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Scroll all the way to the bottom to see which files it uses to configure itself.
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The configuration file itself is very *verbose* and should explain itself.
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### SFTP
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TODO
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