Hands On Networking IPv4 Routing Veena S (MCA Dept) Shruti Kadam, MCA Dept Arpita Kulkarni, MCA Dept June 28, 2012

2 Hands on Networking 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, DNS, Apache WS Socket Programming Take Home –WiFi Access –Software Defined Network Assessment, Feedback 2

3 IP Routing Multi-home vs routing Routing tables –Destination network –Destination mask –Outgoing interface –Next hop –Metric 3

4 IP Routing Commands to add routes route add -net netmask gw Enable routing in multi homed machine (m/c with 2+ interfaces) sysctl -w net.ip4v.ip_forward=1 To see the current routing table route -n netstat -nor To see arp table and set manual entries arp -an arp -s Note: These commands are deprecated. Recommended is to use the commands from iproute2 package ip -4 addr add a.b.c.d/n broadcast dev eth0 ip -4 route add a.b.c.d/n dev eth0 4

5 Building Routers Building actual routers –Middle two m/c have two ethernet network cards These will be converted to routers We will limit to static routing –Do not disturb the existing IP addresses, routing The address range /20 Use alias IP address on this interface ( eth0:1) Do not disturb the default router –Use the address range: /16 to / /16 - Team (15+n) Team N –Divide your address into three or more subnets 172.x.1.0/24, 172.x.2.0/24, 172.x.3.0/24 Use IP addresses from two ends –E.g. 172.x.1.1/24, 172.x.1.254/x –Verify with ping, nc, tcpdump (check TTL) Ensure that packets are actually traversing thru routers 5

6 Building Routers –WE (Workshop exercise)-1 Design/configure two networks Connect via a single router –WE-2 Design/configure three networks Connect via two routers –WE-3 Play with subnet masks /30 to 16 –WE-4 Routing across teams Create routing loops 6

7 Building Routers WE-1: Single Router –Steps to configure IP addresses –Work out the diagrams –Assign addresses and subnet mask properly –Assign routing entries gradually –Do in the step mode gradually –Check reachability one step at a time –Verify IP addresses and routing tables –Enjoy the application communication across your routers 7

8 Building Routers - WE-1

9 Building Routers WE-2 –Two routers with 3 networks 9

10 Building Routers WE-3 –Three networks with variable subletting and two routers 10

11 Building Routers WE-4 –Routing loops –TBD 11