Networking Module 3

ipconfig

provides the user with the IP, subnet mask, and default gateway for each network adapter by default with the /all option information, such as MAC address, DHCP status, and lease information. It is primarily used in Windows.

ifconfig

used to configure the kernel network interfaces. It is implemented at the time of booting to configure the necessary interfaces. Once the interfaces are configured, it is used for debugging or tuning the system. It is primarily used in Linux.

scp

used to securely copy files between servers, leveraging SSH (secure shell) for authentication and encryption.

ftp

copies the file from one host to another host. The data is unencrypted. If encryption is needed, it uses SSL/TLS (Secure Sockets Layer, replaced by Transport Layer Security; the same encryption used in https). Transfer uses TCP (transmission control protocol) for reliability and is often used on the internet and other wide-area networks, where errors may be more common.

traceroute (tracert)

A TCP/IP troubleshooting utility that uses ICMP to trace the path from one networked node to another, identifying all intermediate hops between the two nodes. Traceroute is useful for determining router or subnet connectivity problems. On Windows-based systems, the utility is known as tracert.

dig

A command used to query the DNS name servers. It is helpful in troubleshooting DNS problems. It is also used for lookups and will display answers from the query. It is a replacement for nslookup.

finger

Displays information about a user or users on a remote system, including things such as last log-in time and username. It is primarily used in Linux.

netstat

Displays information about active ports and their state and can be useful in troubleshooting and capacity management. The command (term) -r displays routing information for network adapters. It is available in Windows, MacOS, and Linux.

ARP

Displays the IP to physical (MAC) address mappings for hosts that have been discovered in the (terms) cache. It can be used to add, remove, or modify entries in the (terms) cache. The hosts need to be on the local network, as these addresses are discovered by broadcasting to everyone on the network and noting the reply from the owner; broadcast traffic is not allowed through a router so that the system will maintain the MAC address of the router.

telnet/ssh

Allow a user to manage accounts and devices remotely. The main difference between the two is that SSH is encrypted, and thus all data is secure from eavesdropping, while telnet is unencrypted.

nslookup

Displays DNS name to IP address mappings, DNS information and troubleshooting DNS problems.

tcpdump

Displays TCP/IP packets and other network packets that are being transmitted over the network system. It is a form of protocol analyzer (sometimes called a sniffer) and is designed to show the contents of network packets in human-readable form for troubleshooting, security analysis, etc. Tcpdump is not native to either Linux or Windows but can be downloaded for free and used with both.

route

Used to display or add/remove the current route tables on a host. Should be used to manually enter a computers default gateway (x.x.x.x)

nmap

Scans networks to see what it can find in terms of hosts and open ports (including well-known ones for many applications). It is commonly used to determine what is deployed on a network for vulnerability analysis, security scans, and related activities. Is not native to either Linux or Windows but can be downloaded for free and used with both.

tftp

Transfers a file from either a client to a server or from a server to a client using UDP (user datagram protocol) instead of TCP, and so it is usually used on reliable (local) networks.

whois

a tool most often used to look up who owns a domain or block of IP addresses on the internet, including name, email address, and physical address. However, there are many privacy options that hide this information from being returned. It is primarily used in Linux.

ping

send a message from one computer to another to check whether it is reachable and active. -c limits number of pings in linux, -n in windows