Chapter 4 - Sniffing & Evasion Flashcards
Promiscuous Mode
Has to be set manulaly. NIC will grab anything passed on wire regardless of destination. Tools for this: WinPcap and libpcap (linux)
CSMA/CD
Carrier Sense Multiple Access/Collision Detection - used over Ethernet to decide who can talk
What protocols are susceptible to sniffing
SMTP, FTP, TFTP, IMAP, POP3, NNTP, and HTTP, TCP shows sequence numbers, TCP and UDP show open ports, IP shows source and destination
Collision Domains
Traffic sent from your NIC (regardless of mode) ca nonly be seen within the same collision domain. Hubs have 1 collision domain. Switches have one for each port.
arp -d *
Clears ARP cache
arp -a
Displays current ARP cache
ARP
Address Resolution Protocol: Resolves IP address to MAC addresses. Packets are ARP_REQUEST and ARP_REPLY. Arp -a displays arp cache
Gratuitous ARP
Special packet to update ARP cache even without a request.
IPV6 Loopback address is what?
::1 also uses 128-bit address
IPv6 Address Types
Unicast - Addressed and inteded for one host interface. Multicast - Addresssed for multiple host interfaces. Anycast - Large number of hosts can receive; nearest host opens
IPv6 Scopes
(Scope applies for multicast and anycast). Link Local - Applies only to hosts on the same subnet (Address block fe80::/10) Site Local: Applie to hosts within the same organization (Address block FEC0::/10). Global: Includes everything
Lawful intercetpion
Legally intercepting communications between two parties
Active vs Passive Wiretapping
Active - Interjecting something into communication. Passive - Only monitors and records the data.
Active vs Passive Sniffing
Passive - Watching network traffic without interaction; only works for same collision domain. Active - Uses methods to make a switch send traffic to you even though it isn’t destined for your machine
Span Port
Switch configuration that makes the switch send a copy of all frames from other ports to a specific port. Not all switches can do this.
Network Tap
Special port on a switch that allows the connected device to see all traffic.
Port Mirroring
Another word for span port
CAM Table
The table on a switch that stores which MAC address is on which port. If table is empty or full, everything sent to all ports. This is whats known as MAC flooding
Etherflood
Tool uses to cause MAC flooding
Macof
Tool used to cause MAC flooding
Switch port stealing
Similar to CAM flood. Flood the CAM with unsolicited ARPs. But instead of attempting to fill the table, you’re only interested in updating the information regarding a specific port, causing a race condition
ARP Poisoning
Same as ARP Spoof or Gratuitous ARP. Changes the cache of machines so that packets are sent to you instead of intended target.
What are some countermeasures to ARP poisoning ?
Dynamic ARP Inspection using DHCP snooping. Xarp can also watch for this. Default gateway MAC can be added permanently to machine’s cache.
ARP Poisoning Tools
Cain and Abel, WinArpAttacker, Ufasoft
DHCPv4 Packets
DHCPDISCOVER, DHCPOFFER, DHCPREQUEST, DHCPACK