Networking Laboratory (4140)

Webboard and grades
Academic Honesty


Related Links

Common issues:
Q: Monitor is not showing a PC?
A: Restart the PC and let the X system come on the screen. Do not switch KVM to other PCs.
Q: Where are network configuration files on Linux?
A: /proc/sys/net/ipv4/
Q: Data is not flowing?
A: Check the interface LEDs and wires. Then, check tcpdump/ethereal is listening on correct interface. Then, try the ping. Then, try another interface. Then, ask the TA.

Lab 1 Links
Managing services in Fedora
Linux Networking
Mounting a USB drive, VFAT file system

Lab 2 Links
Tcpdump , pcap, Tcpdump tutorial
Ethereal & Ethereal Wiki
Capture Filters for Ethereal: Ethereal site , SANS Institute Case study ,
ARP Spoofing and Man-in-the-Middle Attacks
Anatomy of an ARP Poisoning Attack

Lab 3 Links
Cisco routers password recovery procedures
Proxy ARP with Linux
We use Cisco 2621XM routers. Description from Cisco. 2600 series architecture .
Cisco IOS essentials on LWEB.
Router configuration link1, link2, link3
Helpful note: There are short names for router commands. Please see section 3.5 in Chapter 3.
Common errors:
- IP forwarding is not enabled in Linux. cat /proc/sys/net/ipv4/ip_forward
Lab 4 Links
RIP RFC 2453, Cisco RIP tutorial, Enabling / disabling split-horizon 
Quagga (Linux RIP, OSPF daemon), Quagga docs
To RIP or to OSPF
See /etc/quagga/ripd.conf. You can enable and disable logging which is very helpful for debugging. See Quagga documentation for editing ripd.conf
OSPF RFC 2328, Cisco OSFP tutorial
Lab 6 Links
Lab 7 Links
Lab 8 Links
Lab 9 Links
[Students: Please provide commands for the functions in RED that will count towards your class participation grade.]
Howto Linux Cisco Router
Connecting to a router

kermit>set line /dev/ttyS0
kermit> set carrier-watch off
kermit> connect


Change IP address [t] ifconfig eth1 netmask
[p] /etc/sysconfig/network-scripts/ifcfg-eth*
Router1(config)# int F0/0 [go to fast ethernet interface 0)
Router1(config-if)# ip addr
Interface up/down ifconfig eth1 up, ifconfig eth1 down Router1(config)# int F0/0
Router1(config-if)# no shut
Change host name [t] hostname my_PC
[p] /etc/sysconfig/network
Router1(config)# hostname router_name
Routing tables

[t] route
[p] /etc/sysconfig/static-routes

Router1(coinfig)# show ip route
Enable routing

[t] echo 1 > /proc/sys/net/ipv4/ip_forward
[p] net.ipv4.ip_forward in /etc/sysctl.conf

Router1(config)# no ip routing
Router1(config)# ip routing
Routing table manipulation [add network prefix] route add -net netmask gw
[add host] route add -host gw
[default gw] route add default gw
[network prefix] Router1(config)# ip route
[host] Router1(config)# ip route
[default gw] Router1(config)# ip route
Packet capture tcpdump -i eth1
ARP [display] arp -a
[delete] arp -d IPAddress
[add] arp -s IPaddress MACaddress
[show] Router1# show ip arp
[delete all] Router1# clear arp-cache
[add] Router1(config)# arp IPaddress
[delete] Router1(config)# no arp IPaddress
Proxy ARP echo 1 > /proc/sys/net/ipv4/conf/eth1/proxy_arp Router1(config)# int F0/0
Router1(config-if)# [no] ip proxy-arp
Network configuration [interfaces] netstat -in
[IP routing table] netstat -rn
[Kernel routing table] netstat -rn, netstat -an, netstat -tan, netstat -uan
[routing cache] route -Cn
[routing cache delete] echo "1" > /proc/sys/net/ipv4/route/flush
[interfaces] Router1# show int
[IP routing table] Router1# show ip route, clear ip route *
[routing cache] [show] Router1# show ip cache
[routing cache] [enable/disable] Router1# [no] ip route-cache
Kernel configuration file /etc/sysctl.conf Router1# show running-config
Services [list all] chkconfig --list
[running services] service --status-all
[start] chkconfig --level 35 sshd on or
/etc/init.d/sshd on
[status] service sshd status
Restart reboot Router1> reload

General Links

List of Internet standards
Cisco documentation
RFCs, IETF working groups
SANS Institute for Information Security, SANS Top 25 Security Papers
Routing software: Zebra GateDT Quagga Click XORP
Traffic Shaping using Linux
John "JI" Ioannidis' Course on Internet Routing

Internet2 Workshop References

  • Troubleshooting Methodology [PDF] [DOC]
  • Cisco/JunOS Multicast Command Reference [DOC]
  • JunOS RIB Group Cheatsheet [DOC]
  • Juniper's JunOS CLI Reference [PDF]