Bridge Note: Uses Open BSD and ? bridge command syntax; pfctl -f /etc/pf.config -------------------- SYNTAX most computers now days have 32 bit processor registers so ip addresses orignally got build on 4 sets of eight (total 32 bits). 01010101.01001010.010101110.00111010 the first octet is what? 64 16 4 1 --- 85? the uw has a class B license that starts at the beginning of the class Bs so 1-127 if the class A license, but 127.0.0.0 is designated for local host use, so 1-126 = class A 192 is our home router internal network address, so 128 - 191 = Class B 224 and up are reserved, so 192 - 223 is for Class C -------------------------------------------- Go To http://www.cabletron.com/support/techtips/tk0231-9.html for instructions on a RJ-45 Plug Pinout (for tcpip cables). -------------------------------------------- From: http://support.microsoft.com/?kbid=314850 Command: ipconfig ipconfig [/? | /all | /renew adapter | /release adapter | /flushdns | /displaydns | /registerdns | /showclassid adapter | /setclassid adapter classid /all Displays full configuration information /release Releases the IP address for the specified adapter /renew Renews the IP address for the specified adapter /flushdns Purges the DNS Resolver cache /registerdns Refreshes all DHCP leases and reregisters DNS names /displaydns Displays the contents of the DNS Resolver Cache /showclassid Displays all the DHCP ClassIds allowed for the specified adapter /setclassid Modifies the DHCP ClassId The default (with no parameters specified) is to display only the IP address, subnet mask, and default gateway for each adapter that is bound to TCP/IP. For /all, Ipconfig displays all of the current TCP/IP configuration values, including the IP address, subnet mask, default gateway, and Windows Internet Naming Service (WINS) and DNS configuration. For /release and /renew, if no adapter name is specified, the IP address leases for all adapters that are bound to TCP/IP are released or renewed. For /setclassid, if no ClassId is specified, the ClassId is removed. EXAMPLES ipconfig Show information ipconfig /all Show detailed information ipconfig /renew Renew all adapters ipconfig /renew EL* Renew any connection whose name starts EL ipconfig /release *Con* Release all matching connections, for example, "Local Area Connection 1" or "Local Area Connection2" ----------------------------------------------------------------------------- Linux Network Commands This page is a resource of the Networking Group of the BTC, affiliated with the College of Computing of Georgia Tech. -------------------------------------------------------------------------------- Any reasonable distribution of Linux has many basic network commands available for installation. This page lists and describes the commands you should have available if you have a Linux box and chose to install networking capabilities. I have tried to make this list fairly complete; if you see any omissions (or rather, if you do not see something that should not have been omitted) then please mail me. I have arranged them according to the following categories: Network Configuration TCP/IP Testing and Troubleshooting Network Clients and Services Network Monitoring Dialup Networking Network Configuration The most fundamental commands are those used to configure network interfaces and policies. While they are primarily of interest to administrators with the responsibility (and permissions) to configure the machine, they permit regular users to at least determine how the machine is set up. Note that most of these commands are used by shell scripts during boot to set up networking automatically. Linux recognizes network interfaces on bootup. (Or at least it does so if the kernel is configured properly.) Each interface is automatically assigned a label - like ``lo0'' for the loopback interface with which the machine talks to itself, ``eth3'' for the fourth internet card installed on the system (since numbering starts with zero), and ``ax0'' for the first Ham radio packet interface present. These commands are presented in the order they would typically be used while setting up networking. ifport(8) If some of your network cards are fancy and support multiple transceiver types, then you start configuration by using this command to specify which transceiver type you will use. ifconfig(8) This command is used to configure network interfaces, or to display their current configuration. In addition to activating and deactivating interfaces with the up and down settings, this command is necessary for setting an interface's address information. An IP interface, for example, needs to be told both its own address and the network mask and broadcast address of its subnet. route(8) Once its interfaces are configured, your machine can receive packets from the network. But where should outgoing packets be sent? Making this decision is called ``routing,'' and it is made by consulting the system's routing table. The destination address of every outgoing packet is checked against every line of this table; if a matching line is found then the packet is sent out the interface listed on that line of the table; if no match is found the system returns the error ``Unreachable host.'' The route command is the tool used to display or modify the routing table. usernetctl(1) Sometimes users are granted the ability to bring certain interfaces up or down on their own; this is the command they use. It is like an emasculated version of ifconfig, that can only turn the interface on or off. ipfwadm(8) If your machine is configured to act as a firewall, you can set up: IP accounting; IP input, forwarding, and output filters; and IP masquerading. This is the command used to perform these functions. It is also used to display the contents of the filter tables. arp(8) When the system transmits a packet, it has to send it to a particular physical-layer address (actually, some messages are sent in broadcast mode, but these are kept to a minimum since they require the attention of every processor connected to the LAN). For instance, when you send an IP packet over Ethernet, it will normally be sent to the Ethernet address of another machine directly connected to it. The ARP (Address Resolution Protocol) table normally uses an automatic mechanism to find what physical addresses go with which IP addresses. The arp command displays this table, and can be used to modify it, though this necessity is rare. TCP/IP Testing and Troubleshooting ping(8) The IP protocol includes control messages called ICMP packets. One type of ICMP packet is called an ``echo request,'' and the IP rules require its recipient to send back an ``echo reply.'' These are incredibly useful because you can determine (1) whether the remote host is up and talking to the network, (2) the time required for a packet to make a round-trip to the host, and (3) (by sending a few dozen echo requests) what fraction of the packets sent between the hosts get lost somewhere along the way. The ping command (named after the sound of an active sonar system) sends echo requests to the host you specify on the command line, and lists the responses received their round trip time. When you terminate ping (probably by hitting control-C) it summarizes the results, giving the average round trip time and the percent packet loss. This command is used constantly to determine whether there is a problem with the network connection between two hosts. traceroute(8) While ping gives information about the performance of the network path between two hosts, traceroute will actually show the route. It attempts to list the series of hosts through which your packets travel on their way to a given destination. Complications can arise that will affect its operation; see the manual page for details. By observing the output of this command, and especially by following it up with pings of specific hosts on the route, the exact location of a bad (high error or latency) link can be discovered. host(1) nslookup(8) dig(1) People like names rather than numbers; ``www.linux.org'' is easier to remember than ``198.182.196.51.'' So the Internet includes a huge distributed database called the Domain Name Service that converts text host names into numeric IP addresses. Basically, the last components of the name are used to identify the server responsible for interpreting the first parts of the name. So a query of ``elvis.mit.edu'' gets sent to a top-level DNS server responsible for ``edu'', which passes the request on to a DNS server at MIT, which knows which machine they call ``elvis''. These commands all perform a DNS query for you. All three can do simple queries (host name to address), reverse queries (address to host name), and more exotic operations (like listing all of the hosts in a domain). The dig command is often considered to give the most behind-the-scenes information for those interested, while host has the simplest default output. Network Clients and Services If you are configuring or running network services, the first package you will be interested in are the TCP wrappers which handle most incoming connections. In the old days, the FTP daemon (for instance) would run when the system started up, grab port 21, and spend the rest of its life listening for and servicing incoming FTP requests. But the fact that each service made its own decision about which connections to accept made the creation and enforcement of a uniform access policy difficult or impossible. These days your system instead contains TCP wrtocol for encapsulating packets. diald(8) The diald daemon monitors your system for network traffic, automatically dials up your Internet service provider whenever you attempt to access the Internet. This prevents you from having to keep up with whether your modem is currently dialed in, while making sure your dialup connection is terminated when you are not using it. At runtime you may configure diald's connection criteria, including how long it should wait before shutting down the modem due to inactivity. -------------------------------------------------------------------------------- Generated 23 June 1998 by Brandon Craig Rhodes, who may be contacted at brandon@rhodesmill.org.