Download TCP/IP Networking and Remote Access

TCP/IP Networking and
Remote Access
Lecture 9
Hassan Shuja
11/23/2004
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TCP/IP Networking and Remote Access
• TCP/IP
– TCP/IP protocol is used on the Internet
– TCP/IP is supported by Windows OS, UNIX, NetWare, Macintosh, MSDOS, and etc...
– IP Addressing
– 32-bit binary number broken up in four 8-bit sections
– Subnet Mask determines the size of the Network ID and the Host ID
– Default Gateway specifies the IP address of the device that needs to be used if
there is a need to communicate outside of the subnet
– “ipconfig /all” , “nslookup”, “ping”, and “traceroute” are good utilities to
troubleshoot TCP/IP issues
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TCP/IP Networking and Remote Access
• Dynamic Host Configuration Protocol (DHCP)
– A DHCP server assigns IP addresses to clients on the network automatically
– IP address is leased to the client for a specific amount of time
– DNS servers are automatically assigned at this time
– DHCP is a service and must be started and only available on all three Server mode
flavors of W2K
– DHCP allows you to manage IP addresses centrally and prevent duplicate IP
addresses
– DHCP also allows for regain of IP addresses if they are no longer being used
– Authorization in AD is needed of the DHCP server before it can begin to work
– Prevents non-authorized W2K servers from coming onto the network and giving out
wrong IP addresses
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TCP/IP Networking and Remote Access
• DHCP (cont.)
– DHCP Server will register non-W2K machines with the DNS server
– A Scope must be set that determines the range of IP addresses that a DHCP
server can assign
– By default no scope exists
– Addresses can be excluded from scope
– In addition to a regular DHCP scope, there are two other types
– Super Scope – A range of IP addresses that spans several subnets
– Multicast Scope – Assigns Class D addresses to clients
– IP Address reservation allows for specific addresses to be only assigned to
specific NIC cards
– Understand process for obtaining DHCP address
– Discussed in Class
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TCP/IP Networking and Remote Access
• Routing
– Routing and Remote Access service needs to be enabled for routing to work
– All 3 flavors of Windows 2000 Server are capable of becoming routers on the
network
– The server that becomes a router needs to have two different methods of
communication
– Either a second NIC card or a modem, ISDN adapter, and etc..
– Static routes can be added for networks behind an interface to build the routing
table
– Dynamic routing uses a routing protocol to build the routing table
– Additional software is needed for dynamic routing
– RIP, OSPF, and IGMP are the different dynamic protocols that can be used
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TCP/IP Networking and Remote Access
• NAT and PAT
– Network Address Translation (NAT) is the translation of many IP addresses
from one range to another
– Port Address Translation (PAT) is the translation of many IP addresses to one
single address
– Routing has to be enabled for a Server to be configured with NAT or PAT
– NAT is configured on a routing interface
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TCP/IP Networking and Remote Access
• Remote Access
– Remote Access is a very important aspect of a network these days because of
such a mobile workforce
– Routing and Remote Access service needs to be enabled for remote access to
work
– This service is only available on the 3 flavors of W2K Server
– Several connection protocols are available for remote access connection
– PPP - Point-to-Point Protocol support multiple transport protocols
– PPMP – Point-to-Point Multilink Protocol is and extension of PPP and combines the
bandwidth from multiple physical connections
– PPTP – Point-to-Point permits a Virtual Private Network (VPN) connection between
two networks
– L2TP – Layer Two Tunneling Protocol is similar to PPTP. The difference is PPTP
uses Microsoft encryption and L2TP uses IPSec encryption
– Microsoft RAS – Used for legacy client computers such as MS-DOS or Windows 3.1.
NetBEUI is the only transport protocol that is allowed
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TCP/IP Networking and Remote Access
• Remote Access
– Authentication can be done through Active directory or a Radius Server
– DHCP can be used to assign IP addresses to remote clients
– Remote Access Server (RAS) can be set to allow IPX, NetBEUI, and AppleTalk
from the client
– Remote Access policies can be set to enhance security and has three
components
– Conditions – Predefined attributes that must be matched by the client. Common
conditions are day and time of connection, client phone number, and computer name
– Permissions – Grants or Denies permission access to the RAS
– Profile – The profile sets such settings as IP address, authentication methods, and
encryption options
– Encryption can be set to the following settings
–
–
–
–
No Encryption
Basic – 56 bit DES L2TP and 40 bit for Microsoft Point-to-Point Encryption (MPPE)
Strong – 56 bit DES or 56 bit for MPPE
Strongest – 168 bit 3DES or 128 bit for MPPE
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