Networking Laboratory (4140)

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 , http://home.insight.rr.com/procana/
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

 

Linux bridges HOWTO, gbrctl

 

Cisco NAT tutorial, NAT entries, iptables tutorial, iptables tutorial2
Video: configuring NAT on a Cisco router

 

 

Lab 9 Links

Net-SNMP, Linux SNMP HOWTO

 

[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 10.0.1.8 netmask 255.255.255.0 [p] /etc/sysconfig/network-scripts/ifcfg-eth*	Router1(config)# int F0/0 [go to fast ethernet interface 0) Router1(config-if)# ip addr 10.0.2.1 255.255.255.0
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 10.21.0.0 netmask 255.255.0.0 gw 10.11.1.4 [add host] route add -host 10.0.2.31 gw 10.0.1.21 [default gw] route add default gw 10.0.4.4	[network prefix] Router1(config)# ip route 10.0.21.0.0 255.255.0.0 10.11.1.4 [host] Router1(config)# ip route 10.0.2.31 255.255.255.255 10.0.1.21 [default gw] Router1(config)# ip route 0.0.0.0 0.0.0.0 10.0.4.4
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
Bridge
NAT
DHCP
Firewall
DNS

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]