Difference between revisions of "OPS335 FTP Lab"

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==VSFTP Setup==
 
==VSFTP Setup==
This lab will show you how to set up an FTP server inside a VM guest on a Fedora 16 host.  
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This lab will show you how to set up an FTP server and provide you with experience identifying configuration parameters that meet your requirements.  
Since you'll be using a VM as the FTP server, you'll only require one lab PC. Remember, these are not group labs - please work individually.
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You'll be using your Centos host as the FTP server and connecting to it from your VMs and from other machines.
 
===Background Information:===
 
===Background Information:===
FTP uses 2 TCP ports. The first, usually port 21, is used to send commands to the server (ls, cd, get, put, etc.) and to receive command replies from the server. The second, usually port 20, is used to send a file to the server during an upload or to receive a file from the server during a download.
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FTP uses 2 TCP ports. The first, usually port 21, is used to send commands to the server (ls, cd, get, put, etc.) and to receive command replies from the server. The second, sometimes port 20, is used to send a file to the server during an upload or to receive a file from the server during a download.
 
*FTP can work in 2 modes: Active or Passive.  
 
*FTP can work in 2 modes: Active or Passive.  
 
**In active mode the client connects to the server on port 21. The server then connects back to the client from port 20. In both connections, the ports used on the client are insecure high-numbered ports ( greater than 1023 ).
 
**In active mode the client connects to the server on port 21. The server then connects back to the client from port 20. In both connections, the ports used on the client are insecure high-numbered ports ( greater than 1023 ).
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[[Image:Passive-ftp.png]][[Image:Active-ftp.png]]
 
[[Image:Passive-ftp.png]][[Image:Active-ftp.png]]
  
===Build your VM===
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===Configure your VM===
*Power up your PC (the gateway with host name f16), login as your user-id, open a terminal window and "su" to root.
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*Power up your PC (the gateway with host name host), login as your user-id, open a terminal window and "su" to root.
 
*Check the settings on your firewall.  Ensure that you can still use the services you have configured in previous labs.
 
*Check the settings on your firewall.  Ensure that you can still use the services you have configured in previous labs.
*Check your firewall using the "iptables-save" command.
 
 
*Now make sure you are connected to the Internet. Start Firefox and authenticate yourself into the network.
 
*Now make sure you are connected to the Internet. Start Firefox and authenticate yourself into the network.
*Still as root you need to install an ftp client. Use this command: "yum install ftp".
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*Login to your VM1 and ensure you have the firewall set up to allow the services you have previously configured (e.g. DNS, apache).  If those services are not functioning, fix them (or your firewall) now.
*Login to your VM01 and ensure you have the firewall set up to allow the services you have previously configured (e.g. DNS, mail).  If those services are not functioning, fix them (or your firewall) now.
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Before preceeding to the next part ensure your gateway is working properly and that your server has access to the Internet. Try some of these commands on your VM/guest:
Before preceeding to the next part ensure your gateway is working properly and that your server has full access to the Internet. Try some of these commands on your VM guest:
 
 
   ping 192.168.X.1
 
   ping 192.168.X.1
 
   host cbc.ca
 
   host cbc.ca
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===Set up your FTP Server (Passive Mode)===
 
===Set up your FTP Server (Passive Mode)===
#Still on vm01 use yum to install vsftpd and edit the config file (/etc/vsftpd/vsftpd.conf) to implement the following:
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*On your Centos host you should not need to install vsftpd.  If it is not present, install it.
#*Anonymous users should be able to login and download any files (permissions allowing) from the /var/ftp/pub.  
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  yum install vsftpd
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#Edit the config file (/etc/vsftpd/vsftpd.conf) to implement the following:
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#*Anonymous users should be able to login and download any files (permissions allowing) from the directory /var/ftp/pub.  
 
#*Anonymous uploading should not be allowed.  
 
#*Anonymous uploading should not be allowed.  
#*Local users should be allowed to login to their own accounts and upload/download their own files.
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#*Prevent local accounts from logging in.
#The FTP Greeting Banner should be set to "Welcome to OPS335 FTP Server".
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#*The FTP Greeting Banner should be set to "Welcome to my OPS335 FTP Server".
#Set the maximum number of concurrent client connections to 50.
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#*Set the server to listen on IPv4 sockets, not IPv6.
#Set the maximum transfer rate for anonymous users to 110912 bytes per second.
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#*Set the maximum number of concurrent client connections to 30.
#Set the connection timeout for all clients to 90 seconds.
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#*Set the maximum transfer rate for anonymous users to 140300 bytes per second.
#Enable file transfer logging.
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#*Set the connection timeout for idle clients to two minutes.
#You'll now have to modify your vm01 firewall to allow NEW tcp connections on port 21.
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#*Enable file transfer logging.
#You'll also need to set SELinux to permissive mode: setenforce 0.
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#*Limit the range of ports passive mode is allowed to use to 14335 to 14935.
#Finally you'll have to install the ftp connection tracking module into your kernel. Use this command: "modprobe nf_conntrack_ftp". To verify that your kernel module is installed you can use the "lsmod" command.
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#You'll now have to modify your firewall to allow NEW tcp connections on port 21, and tcp connections on the same ports vsftp is will use for data connections.
#At this point you should test your FTP server from hosts within your intranet. It should work properly for both anonymous and local users. From a terminal window on the gateway try these activities:
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#Verify that the ftp connection tracking module is installed in your kernel with the "lsmod" command. If it is not, you'll have to install it with the command: "modprobe nf_conntrack_ftp".
#*ftp as joker on your VM, then list, get and put files.
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#Start your ftp server.
#*ftp as anonymous to your VM, then list and get files.
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#From the command line of your server, create a new file (or several) in /var/ftp/pub.
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#Change the ownership of the /var/ftp/pub directory to the user ftp.
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#At this point you should test your FTP server from other hosts within your intranet. It should allow anonymous users to retrieve files. From one of your VMs try these activities:
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#*ftp using the login 'ftp' to your host, then list and get the file you created.
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#*Try logging is as a user that exists on that machine.
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===Connecting from outside your intranet===
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*Now configure your firewall (using iptables) on the gateway machine to allow FTP clients from outside your network (if you did not already do so).
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*Test your firewall by logging into a second PC (try both Windows and Linux) and attempt an FTP connection to your gateway PC. Test the anonymous user's ability to list and get files again.
  
===Configure the Firewall===
 
*Now configure your firewall (using iptables) on the gateway to allow FTP clients through to the vm01 FTP server.
 
*You'll need to forward packets with destination port 21 to your VM machine.
 
*Test your firewall by logging into a second PC (try both Windows and Linux) and attempt an FTP connection to your gateway PC. Test both local user as well as anonymous connections.
 
 
===Set up your FTP Server (Active Mode)===
 
===Set up your FTP Server (Active Mode)===
#Edit /etc/vsftpd/vsftpd.conf and disable Passive mode (so now only Active mode is enabled) and then restart vsftpd.
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#Edit /etc/vsftpd/vsftpd.conf and disable Passive mode, ensure active mode is enabled, and then restart vsftpd.
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#Add any iptables rules necessary to allow active connections.
 
#Test your firewall by logging into a second PC (try both Windows and Linux) and attempt an FTP connection to your gateway PC. Test both local user as well as anonymous connections.
 
#Test your firewall by logging into a second PC (try both Windows and Linux) and attempt an FTP connection to your gateway PC. Test both local user as well as anonymous connections.
===Log Packets with Netfilter===
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#On the firewall/gateway add iptables log rules to monitor ftp traffic (control and data) for the following:
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===Log Packets with iptables===
#*PREROUTING chain of nat table
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#On the firewall/gateway add iptables log rules to monitor ftp traffic (control and data) from outside your network in both of the following.
#*FORWARD chain of filter table
 
#*POSTROUTING chain of nat table
 
#On vm01 add iptables log rules to monitor ftp traffic (control and data) for the following:
 
#*PREROUTING chain of nat table
 
 
#*INPUT chain of filter table
 
#*INPUT chain of filter table
 
#*OUTPUT chain of filter table
 
#*OUTPUT chain of filter table
#*POSTROUTING chain of nat table
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#While monitoring your packets using "tail -f /var/log/messages" - test your firewall logs by connecting from one of your VMs, and then by logging into a second PC (try both Windows and Linux) and attempt an FTP connection to your gateway PC. Test both local user as well as anonymous connections.
#*While monitoring your packets using "tail -f /var/log/messages" - test your firewall by logging into a second PC (try both Windows and Linux) and attempt an FTP connection to your gateway PC. Test both local user as well as anonymous connections.
 
  
 
==Completing the Lab==
 
==Completing the Lab==
Answer the following questions and and email them to your teacher in ASCII text format.
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In completing this lab you have gained experience using a service that has multiple modes.  You have practiced researching configuration parameters to find the ones you need.  This will be an invaluable skill, as you will not usually have anyone telling you specifically which parameters to set, or what values to set them to.
#What is your full name and 9-digit Seneca student ID?
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#Hand in your output from the following commands on the FTP server:
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#*cat /etc/vsftpd/vsftpd.conf | grep -v ^# | awk 'NF>0'
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Exploration questions:
#*cat /var/log/xferlog
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#What parameters did you use to force vsftp to use active mode only.
#*iptables-save
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#What version number of vsftpd are you using.
#Hand in your output from the following commands on the gateway:
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#What parameters would you set to configure vsftp to use ssl for authentication.
#*iptables-save
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#If you wanted to allow your local users to access their files through ftp, what parameters would you set, and what would you set them to?
#Show the log files on both the gateway (f13) and the server (vm01) generated during while logging packets with Netfilter.
 

Latest revision as of 18:02, 30 November 2015


VSFTP Setup

This lab will show you how to set up an FTP server and provide you with experience identifying configuration parameters that meet your requirements. You'll be using your Centos host as the FTP server and connecting to it from your VMs and from other machines.

Background Information:

FTP uses 2 TCP ports. The first, usually port 21, is used to send commands to the server (ls, cd, get, put, etc.) and to receive command replies from the server. The second, sometimes port 20, is used to send a file to the server during an upload or to receive a file from the server during a download.

  • FTP can work in 2 modes: Active or Passive.
    • In active mode the client connects to the server on port 21. The server then connects back to the client from port 20. In both connections, the ports used on the client are insecure high-numbered ports ( greater than 1023 ).
    • In passive mode the client first connects to the server on port 21 and makes a second connection to a high-numbered port. As with active mode, the ports used on the client are insecure high-numbered ports ( greater than 1023 ).

FTP can be set up so that anonymous users (users without accounts on the server) may download and possibly upload files.
Passive-ftp.pngActive-ftp.png

Configure your VM

  • Power up your PC (the gateway with host name host), login as your user-id, open a terminal window and "su" to root.
  • Check the settings on your firewall. Ensure that you can still use the services you have configured in previous labs.
  • Now make sure you are connected to the Internet. Start Firefox and authenticate yourself into the network.
  • Login to your VM1 and ensure you have the firewall set up to allow the services you have previously configured (e.g. DNS, apache). If those services are not functioning, fix them (or your firewall) now.

Before preceeding to the next part ensure your gateway is working properly and that your server has access to the Internet. Try some of these commands on your VM/guest:

 ping 192.168.X.1
 host cbc.ca

also use lynx from your vm to ensure you can view internal and external web sites.

Set up your FTP Server (Passive Mode)

  • On your Centos host you should not need to install vsftpd. If it is not present, install it.
 yum install vsftpd
  1. Edit the config file (/etc/vsftpd/vsftpd.conf) to implement the following:
    • Anonymous users should be able to login and download any files (permissions allowing) from the directory /var/ftp/pub.
    • Anonymous uploading should not be allowed.
    • Prevent local accounts from logging in.
    • The FTP Greeting Banner should be set to "Welcome to my OPS335 FTP Server".
    • Set the server to listen on IPv4 sockets, not IPv6.
    • Set the maximum number of concurrent client connections to 30.
    • Set the maximum transfer rate for anonymous users to 140300 bytes per second.
    • Set the connection timeout for idle clients to two minutes.
    • Enable file transfer logging.
    • Limit the range of ports passive mode is allowed to use to 14335 to 14935.
  2. You'll now have to modify your firewall to allow NEW tcp connections on port 21, and tcp connections on the same ports vsftp is will use for data connections.
  3. Verify that the ftp connection tracking module is installed in your kernel with the "lsmod" command. If it is not, you'll have to install it with the command: "modprobe nf_conntrack_ftp".
  4. Start your ftp server.
  5. From the command line of your server, create a new file (or several) in /var/ftp/pub.
  6. Change the ownership of the /var/ftp/pub directory to the user ftp.
  7. At this point you should test your FTP server from other hosts within your intranet. It should allow anonymous users to retrieve files. From one of your VMs try these activities:
    • ftp using the login 'ftp' to your host, then list and get the file you created.
    • Try logging is as a user that exists on that machine.

Connecting from outside your intranet

  • Now configure your firewall (using iptables) on the gateway machine to allow FTP clients from outside your network (if you did not already do so).
  • Test your firewall by logging into a second PC (try both Windows and Linux) and attempt an FTP connection to your gateway PC. Test the anonymous user's ability to list and get files again.

Set up your FTP Server (Active Mode)

  1. Edit /etc/vsftpd/vsftpd.conf and disable Passive mode, ensure active mode is enabled, and then restart vsftpd.
  2. Add any iptables rules necessary to allow active connections.
  3. Test your firewall by logging into a second PC (try both Windows and Linux) and attempt an FTP connection to your gateway PC. Test both local user as well as anonymous connections.

Log Packets with iptables

  1. On the firewall/gateway add iptables log rules to monitor ftp traffic (control and data) from outside your network in both of the following.
    • INPUT chain of filter table
    • OUTPUT chain of filter table
  2. While monitoring your packets using "tail -f /var/log/messages" - test your firewall logs by connecting from one of your VMs, and then by logging into a second PC (try both Windows and Linux) and attempt an FTP connection to your gateway PC. Test both local user as well as anonymous connections.

Completing the Lab

In completing this lab you have gained experience using a service that has multiple modes. You have practiced researching configuration parameters to find the ones you need. This will be an invaluable skill, as you will not usually have anyone telling you specifically which parameters to set, or what values to set them to.


Exploration questions:

  1. What parameters did you use to force vsftp to use active mode only.
  2. What version number of vsftpd are you using.
  3. What parameters would you set to configure vsftp to use ssl for authentication.
  4. If you wanted to allow your local users to access their files through ftp, what parameters would you set, and what would you set them to?