Hands On Networking Network Applications Ram P Rustagi, ISE Dept Kundan Kumar, MCA Dept Manini Sahoor, MCA Dept Ravi Teja, MCA Dept Sourav Mandal, MCA Dept June 30, 2012

2 Course contents General Networking Overview –Network Configuration –tools/utilities Building (IPv4) routing networks Using ARP to advantage Studying ICMP Network security issues Bandwidth Management, Queuing IPv6: Routing, working with IPv4 networks NAT and load balancing Installing/configuring Network applications –DHCP, FTP, Apache WS, Socket Programming Take Home –WiFi Access –Software Defined Network Assessment, Feedback 2

3 Web Server HTTP protocol –Headers –Methods –Request and status line –Persistent connection –SSL certificate Valid for a name WE-1 –Install Apache, and setup socket (other than 80) Enable directory listing WE-2 –Configure to have password based access for directories WE-3 –Configure to have virtual hosts WE-4 –Install SSL certificate (Self signed) 3

Web Server – WE 1 Displaying Directory listing –By default following is enabled Options Indexes index.html, index.php is present – Removing index.html/index.php will do the work – Alternatively, play with Options Indexes 4

Web Server – WE 2 Password protecting the directories –Create a password file htpasswd /etc/apache2/passwdfile user_name For first time, use –c option to create the file Using –c option for existing file will rewrite Add entries for each required user – Specify the password file in /etc/apache2/apache2.conf AuthType Basic AuthName "By Invitation" AuthUserFile /etc/apache2/passwdfile Require valid-user – Restart the web server /etc/init.d/apache2 restart 5

Web Server – WE 4 Generating Self Signed Certificate –What is SSL Certificate Enables to encrypt the sites content when sent on connection Enables client to verify the site –What the site says it is and what the site client connected to Contains the following information –Validity period –Sitename –Certificate authority  In our case, this will be us  Typically, it is Verisign, Thawte, GoDaddy etc. –Enabling SSL module a2enmod ssl – Create a directory to keep certificate file mkdir /etc/apache2/ssl 6

Generating the certificate –Need three files –Replace with website name – private key file – request file for certificate signing – actual certificate file –Generating key file (for website rpr.pesise.in ) openssl genrsa -des3 -out rpr.pesise.in.key 1024 –Need to enter some passphrase –Generating a request file for certificate signing openssl req -new -key rpr.pesise.in.key -out rpr.pesise.in.csr – Generate the actual certificate file openssl x509 -req -days 730 -in rpr.pesise.in.csr -signkey rpr.pesise.in.key - out rpr.pesise.in.crt 7 Web Server – WE 4

Installing the certificate –Edit the following SSL config file /etc/apache2/sites-available/default-ssl – Modify the following entries ServerName rpr.pesise.in:443 SSLEngine on SSLCertificateFile /etc/apache2/ssl/rpr.pesise.crt SSLCertificateKeyFile /etc/apache2/ssl/rpr.pesise.in.key – Enable the default virtual host a2ensite default-ssl – Restart apache – Access the site as 8 Web Server – WE 4

9 DHCP –Setting DHCP –DHCP with relay agents –DHCP with fixed IP addresses –DHCP with options –Blocking communication among clients WE-1 –Configuring simple DHCP server WE-2 –Configuring DHCP server with reserved IP WE-3 –Configuring options Timeouts Blocked communication among recipients 9

10 Installing FTP Server FTP overview –Control channel (port 21) –Data channel (port 20 on client side) –Active vs passive FTP 10

Using server vsftpd (very secure FTP Daemon) –sudo apt-get install vsftpd – Edit the config file /etc/vsftpd.conf to make changes anonymous_enable=YES write_enable=YES pasv_enable=YES ## if needed – Restart FTP daemon sudo service vsftpd restart – Use ftp client to connect to FTP server Upload/download files 11 Installing FTP Server

12 Installing Applications involves –Server Accepts using SMTP –Clients Retrieves mail using POP3/IMAP4 protocol Software being used –postfix –mailutils for local clients –Installing software sudo apt-get install postfix sudo apt-get install mailutils 12

application Sending s Receiving s 13