Chapter 7 TCP/IP Implementation Flashcards
The DHCP Leases Process:
- Discover- Once a node comes online and loads a simple version of TCP/IP and it’s ready to communicate with a DHCP server, it transmits a broadcast called a DHCP discover to the network’s broadcast address of 255.255.255.255 to see if any DHCP servers are online and then request an IP address.
- Offer- DHCP servers that are online respond with a directed lease offer packet that contains an IP address that the node can lease.
- Request- The node accepts the first offer it receives and returns a request to lease the IP address from the DHCP server.
- Acknowledge- The DHCP server acknowledges the request from the node with a DHCP ACK, which has the IP address and settings required for the leasing time and starts the lease.
the predecessor of DHCP. It was developed to assign IP addresses to diskless workstations that had no way of storing their operating system.
BOOTP (the bootstrap protocol)
are lease assignments in DHCP that enable you to configure a permanent IP address for a particular client on the subnet. Reserved IP addresses differ from statically configured IP addresses; when there are any changes in network parameters on the DHCP server, IP addresses receive the changes when they renew their leases.
DHCP Reservations
a service that captures a BOOTP or DHCP broadcast and forwards it through the router as a unicast transmission to the DHCP server on another subnet. You must either have a DHCP server on each subnet and configure the router to forward the broadcasts, or configure one of these
DHCP Relay Agent
a service that enables a DHCP client device to configure itself automatically with an IP address in the range of 169.254.0.1 to 169.254.255.254, in case no DHCP servers respond to the client’s DHCP discover broadcast. APIPA addresses are not routable, so devices with APIPA addresses cannot communicate outside of the local subnet.
Automatic Private IP Addressing (APIPA)
windows command that displays connection-specific DNS suffix, IP address, subnet mask, and default gateway information. /release forces the release of an IP address. /renew requests the renewal of an IP address.
Ipconfig
command displays the status of currently active network interface devices on Linux and Unix. Iwconfig for wireless devices on Linux and Unix
Ifconfig
Enables you to configure and manage DHCP settings on the network interfaces of a computer. Supported on Linux and Unix.
Dhclient
Ping command options:
- Packet Size - by default, data packets are sent as re bytes. You can specify a larger size to response time. Example ping target [-1 size]
- TTL- A value that determines how many hops an IP packet can traverse before being discarded. Example ping target [-i TTL]
- Packet Count- Specifies the number of packets with which a remote host is pinged. Default is four packets. Example ping target [-n packet count]
- Continuous ping- Pings the specified host until the command is interrupted by pressing Ctrl+C. Example ping target -t
- IPv6- Ping using IPv6. Example ping target -6
As a security measure, some public Internet hosts and routers might be configured to block incoming packets that are generated by the ping command and is known as this.
ICMP Blocking
a number that represents a process running on a network. associated with OSI Layer 5, but in every packet, there will be both a source and destination one embedded in the Transmission Control Protocol (TCP) or User Datagram Protocol (UDP) header.
Ports
Port # and Protocol(s) for FTP Data File Transfer - Default Data
20 & TCP
Port # and Protocol(s) for
21 & TCP
Port # and Protocol(s) for SSH - Secure Shell & SFTP - Secure File Transfer Protocol
22 & TCP, UDP
Port # and Protocol(s) for Telnet
23 & TCP, UDP
Port # and Protocol(s) for SMTP
25 & TCP
Port # and Protocol(s) for DNS
53 & TCP, UDP
Port # and Protocol(s) for BOOTPS - DHCP (BOOTP) server
67 & TCP, UDP
Port # and Protocol(s) for BOOTPC - DHCP (BOOTP) client
68 & TCP, UDP
Port # and Protocol(s) for TFTP
69 & UDP
Port # and Protocol(s) for HTTP
80 & TCP
Port # and Protocol(s) for POP3 - Post Office Protocol, version 3 (POP3)
110 & TCP
Port # and Protocol(s) for NTP - Network Time Protocol (NTP)
123 & UDP
Port # and Protocol(s) for IMAP - IMAP
143 & TCP, UDP
Port # and Protocol(s) for SNMP - Simple Network Management Protocol (SNMP)
161 & UDP
Port # and Protocol(s) for IRC - Internet Relay Chat (IRC)
194 & TCP
Port # and Protocol(s) for IDAP - Lightweight Directory Access Protocol (LDAP)
389 & TCP, UDP
Port # and Protocol(s) for HTTPS - HTTP-secure
443 & TCP
Port # and Protocol(s) for SMB - Server Message Block (SMB)
445 & TCP
Port # and Protocol(s) for LDAPS - Secure LDAP
636 & TCP, UDP