IP Interface Configuration in Windows
1. IP Configuration:
o Each host adapter needs an IP address, subnet mask, and default gateway.
o DNS server addresses are also usually configured.
2. Static vs. Dynamic Configuration:
o Static IP addressing can be complex for large numbers of hosts.
o Dynamic IP addressing via DHCP is more common for ease of management.
3. Naming Conventions:
o Windows adapters: "Ethernet", "Ethernet2", etc.
o Configuration through GUI or command line.
4. Command Line Tools:
o netsh: Configure and view IP settings.
▪ netsh interface ip set address "Ethernet" dhcp
▪ netsh interface ip set address "Ethernet" static 10.1.0.1
255.255.255.0 10.1.0.254
▪ netsh interface ip show config
o PowerShell:
▪ Query configuration: Get-NetAdapter, Get-NetIPAddress
▪ Apply configuration: New-NetIPAddress, Set-NetIPAddress
5. ipconfig Command:
o ipconfig: Basic IP information.
o ipconfig /all: Detailed configuration including DHCP and MAC addresses.
o ipconfig /renew: Renew DHCP lease.
o ipconfig /release: Release DHCP lease.
o ipconfig /displaydns: Display DNS cache.
o ipconfig /flushdns: Clear DNS cache.
o ipconfig /registerdns: Register the host with a DNS server.
IP Interface Configuration in Linux
1. Interface Naming:
o Legacy: eth0, eth1, etc.
o Newer conventions: enp0s3, etc.
2. Persistent vs. Running Configuration:
o Persistent configuration applied at boot.
o Running configuration can be changed but needs to be made persistent.
3. Configuration Tools:
o Legacy Tools:
▪ ifconfig: Deprecated for managing interfaces.
▪ ifup/ifdown: Scripts to bring interfaces up/down.
o Modern Tools:
▪ ip command (part of iproute2 package):
▪ Show configuration: ip addr
▪ Show single interface: ip addr show dev eth0
▪ Enable/disable interface: ip link set eth0 up|down
▪ Modify IP configuration: ip addr add|delete
▪ NetworkManager and nmcli: Manage network settings.
▪ systemd-networkd and netplan: Manage network settings in newer
distributions.
ARP Cache Utility
1. Purpose: Resolve and cache MAC addresses for IP addresses on the local network.
2. Commands:
o Windows:
▪ arp -a or arp -g: Show ARP cache.
▪ arp -s IPAddress MACAddress: Add ARP entry.
▪ arp -d *: Delete all ARP entries.
o Linux:
▪ ip neigh: Show ARP cache.
ICMP and ping Utility
1. Purpose: Test and troubleshoot connectivity using ICMP packets.
2. Basic Usage:
o ping IPAddress: Send ICMP request packets to the destination host.
3. Interpreting Results:
o Successful reply: "Reply from IPAddress" with RTT.
o Number of hops: TTL field (initial value minus current TTL).
4. Error Messages:
o "Destination host unreachable": No routing information.
o "Request timed out": Host is unavailable or cannot route a reply.
5. Common Switches:
o -t: Ping until interrupted.
o -4 or -6: Force IPv4 or IPv6.
o -c: Specify the number of packets to send (Linux).
TCP/IP Command Line Utilities:
• Purpose: Gather configuration information and troubleshoot communication issues over an
IP network.
• netsh: Configure and report IP settings in Windows.
o netsh interface ip set address "Ethernet" dhcp (Set DHCP)
o netsh interface ip set address "Ethernet" static 10.1.0.1
255.255.255.0 10.1.0.254 (Set static IP)
o netsh interface ip show config (Show IP configuration)
• PowerShell: More commonly used for script-based configuration.
o Get-NetAdapter, Get-NetIPAddress (Query configuration)
o New-NetIPAddress, Set-NetIPAddress (Apply or modify configuration)
• ipconfig: Basic configuration reporting.
o ipconfig (Display basic IP configuration)
o ipconfig /all (Complete TCP/IP configuration)
o ipconfig /renew, ipconfig /release (DHCP commands)
o ipconfig /displaydns, ipconfig /flushdns, ipconfig /registerdns
(DNS commands)
• Linux equivalents: ifconfig, ip (iproute2 package), nmcli (NetworkManager), systemd-
networkd, netplan.
ARP Cache Utility:
• Purpose: Diagnose local addressing and packet delivery problems.
• Commands:
o arp -a (Show ARP cache)
o arp -s IPAddress MACAddress (Add ARP entry)
o arp -d * (Delete ARP entries)
• Linux command: ip neigh (Replaces arp).
ICMP and ping:
• Purpose: Report errors and test connectivity.
• Basic Usage: ping IPAddress
• Error Messages:
o "Destination host unreachable" (No routing information)
o "Request timed out" (Host unavailable or cannot route a reply)
• Switches:
o -t (Continuous ping)
o -4 or -6 (Force IPv4 or IPv6)
Network Troubleshooting:
Hardware and Interface Issues:
• Power Issues: Surges, spikes, brownouts, blackouts. Use UPS for protection.
• Hardware Failure: Check network adapters, switches, routers, and cabling. Use cable testers
and status LEDs.
• Interface Status: Verify with LEDs, command line utilities. Check for speed/duplex
mismatches and collisions.
IP Configuration Issues:
• Incorrect IP Address: Ensure correct subnet masks and unique IP addresses.
• Incorrect Subnet Mask: Mismatched masks can cause routing issues.
• Duplicate IP/MAC Address: Use arp -a, arping to detect and resolve conflicts.
Connectivity Tests:
1. Loopback Address: ping 127.0.0.1
2. Local Host IP Address: Ensure proper network adapter function.
3. Default Gateway: Verify router connectivity.
4. Other Hosts on Same Subnet: Test for local link issues.
5. Remote Host: Check routing through the gateway.
DNS Issues:
• DNS Configuration: Use ipconfig /all (Windows) or check /etc/resolv.conf (Linux).
• Ping by Host Name: Troubleshoot name resolution problems.
Multicast Flooding:
• Problem: Switches flood multicast traffic if not multicast-aware.
• Solution: Enable IGMP snooping to filter multicast traffic.
IPv4 vs. IPv6
• IPv4: 32-bit addresses, approx. 4.3 billion addresses.
• IPv6: 128-bit addresses, approx. 340 undecillion addresses.
• IPv4 address exhaustion due to inefficient allocation and high demand.
IPv6 Address Format
• Structure: Eight groups of four hex digits, separated by colons.
• Example: 2001:0db8:0000:0000:0abc:0000:def0:1234.
• Compression: Leading zeros can be omitted, and consecutive zeros can be replaced
with "::" (only once per address). For example, 2001:db8::abc:0:def0:1234.
Address Types and Prefixes
• Global Unicast: Routable on the Internet (Prefix: 2000::/3).
• Link Local: Used within a single link (Prefix: fe80::/10).
• Multicast: One-to-many communication (Prefix: ff00::/8).
• Unspecified: 0:0:0:0:0:0:0:0 (often ::).
• Loopback: 0:0:0:0:0:0:0:1 (often ::1).
• Documentation/Examples: Prefix 2001:db8::/32.
IPv6 Header Fields
• Traffic Class: Packet priority.
• Flow Label: QoS management.
• Payload Length: Length of payload (max 64 KB, or Jumbo Payload for larger).
• Next Header: Type of the next header.
• Hop Limit: Replaces TTL in IPv4.
Address Configuration
• Interface ID: Last 64 bits of an address.
• EUI-64: Derived from the MAC address, with "fffe" inserted in the middle.
• Privacy Extensions: Uses pseudorandom numbers for interface IDs to enhance
privacy.
Neighbor Discovery Protocol (ND)
• Functions:
o Address Autoconfiguration: Automatic configuration of IP addresses.
o Prefix Discovery: Determines network prefixes.
o Local Address Resolution: Finds local nodes and routers.
o Redirection: Indicates better routes.
Stateless Address Autoconfiguration (SLAAC)
• Generates link-local addresses.
• Uses ND protocol to test uniqueness and discover routers.
• Can combine with DHCPv6 for stateful autoconfiguration.
ICMPv6
• Similar to ICMPv4 but includes new features like "Packet Too Big" messages.
• Supports ND and MLD protocols.
Transition Mechanisms
• Dual Stack: Hosts run both IPv4 and IPv6.
• Tunneling: Encapsulates IPv6 packets within IPv4 packets (e.g., 6to4, 6RD, Teredo,
GRE).
Common IPv6 Address Prefixes
• Global Unicast: 2000::/3.
• Link Local Unicast: fe80::/10.
• Multicast: ff00::/8.
• Multicast (Link Local): ff02::/16 (e.g., ff02::1 for all nodes, ff02::2 for all routers).
• Solicited-node: ff02::1:ff00:0/104
