Tcp/ip

TCP/IP FAQ
1. What is the Internet?

The Internet is a network of computer networks. A network consists of two or more computers that are
interconnected physically and capable of communicating and sharing data with each other. The Internet
is a collection of these individual networks.

2. How did the Internet start?

The Internet started in 1969 when the U.S. Department of Defense created ARPANET, a network
connecting four universities and their computer networks. More universities were added over the years.
In 1985 the National Science Foundation established a network of supercomputing centers and several
regional networks connected to the "super centers." These events formed the backbone of today’s
Internet.

3. What does the Internet provide?

The Internet provides access to data, text, sound, graphics, software and communication.

4. How does the Internet provide these things?

There are several different methods for moving information across the Internet. These include hypertext
(WWW), remote login (telnet), file transfer (ftp), and electronic mail (email). All of these technologies
are simply ways to get information from one computer to another via the Internet.

5. What is a protocol?

In order for different types of computers on the Internet network to understand each other, all
computers must follow a set of rules called a protocol in order to communicate with each other.

This is similar in some ways to a ‘language’ in that computers and other network devices such as routers
‘talk’ to each other using the ‘grammar rules’ and vocabulary of the TCP/IP protocol.

6. What protocol does the Internet use?

Computers on the Internet use the TCP/IP protocol to communicate with each other.

7. What does TCP/IP stand for?

TCP/IP stands for Transmission Control Protocol/Internet Protocol.

8. How does TCP/IP work?

TCP/IP works like mailing a letter. There are two components. IP places the data in an "envelope" and
addresses it, similar to putting a letter in an envelope. It also enables the network to read the envelope’s
address and forward the data to its destination. TCP breaks up the envelope into data "packets" that the

network can handle. TCP verifies that all packets arrive at their destination and reassembles the packets
for the recipient to use.

9. What is Internet addressing?

All information communicated over the Internet requires an address, just like a letter mailed at a post
office. Internet addressing is a systematic way to identify people, computers and Internet resources. An
example would be an email address (jsmith@hospital.com) or a web address
(http://www.hospital.com/). There are two main parts to Internet addressing, the IP address and the
domain name.

10. What is an IP address?

For a computer to use TCP/IP to communicate information to another computer, you need to know the
other computer’s address. An IP address is a specific address for a specific computer on a specific
network. This number tells TCP/IP exactly where the information "packet" should be sent. IP addresses
are unique—no two computers can have the same address.

11. What does an IP address look like?

An IP address consists of four sections separated by periods. Each section contains a number between 0
and 255. An example would be: 111.22.3.44

12. What is a domain name?

A domain name is another way to identify computers on the Internet. A domain name corresponds to a
specific IP address. Internet users only have to remember the domain name, rather than the numerical
IP address. Each domain name corresponds to a specific IP address.

13. What does a domain name look like?

A domain name consists of two or more sections separated by periods called "dots." Some examples of
domain names include: hospital.org, medical.school.edu, and nasa.gov.

14. How are domain names organized?

All domain names contain a top-level designation which describes the type of organization. The
following describe the initial set of top-level domain names in 1984. More were added in recent years.

COM: commercial entity

EDU: colleges and universities

NET: Internet organizations such as Internet Service Providers

ORG: miscellaneous groups such as non-profit organizations

GOV: United States Government

MIL: United States Military

The rest of the address may contain the name of the organization or company, location, or other
information. Example: library.medicalschool.stateuniversity.edu

15. How do you connect to the Internet?

There are two main ways to connect to the Internet: 1) Direct Network Connection 2) Internet Service
Provider.

16. What is a direct network connection?

A direct network connection is generally the fastest but usually the most expensive way to connect to
the Internet. With a direct connection the user’s computer is part of a network which is physically
connected to the Internet. No modem is necessary with direct connections, but generally special
hardware such as a network interface card (NIC) must be installed in the computer in order to connect in
this manner. Direct network connections are generally found in large organizations which can afford the
considerable amount of hardware and software required to maintain a direct Internet connection.

17. What is an Internet Service Provider?

An Internet Service Provider or ISP is a company or other organization such as a university that provides
access to the Internet (sometimes for a fee such as TRUE, AIS or DTAC. ISPs may also provide email
accounts to their customers. Their customers can be businesses, individuals, or organizations. ISPs
provide access to the Internet via several methods, including dial-up modems, high-speed DSL, cable,
fiber optic, satellite, or wireless broadband access (Edge,3G/4G).

18. What is Dial-Up Modem Internet Access?

Dial-up Internet access is made available via standard telephone lines. User needs a modem connected
to a telephone line to dial into an ISP’s node, in order to establish connection. Although dial-up has been
replaced by broadband Internet access (see below) in many parts of the world, it still is a good option for
rural or remote areas where broadband access is not feasible, or for users who have limited budget.

19. What is high-speed DSL?

High-speed DSL also relies on a local standard telephone network, but provides much faster connection
speed than standard dial-up because DSL lines use phone lines that are specially configured to allow
much larger amounts of data to be transmitted. A DSL modem is required to get access from the ISP. DSL
also allows users to access the Internet while making phone calls simultaneously without interfering
each other.

20. What is Cable Internet?

Cable companies offer high-speed Internet access using existing residential cable television network.
Cable, like DSL, allows much larger amounts of data to be transmitted than regular phone lines, allowing
for a much high Internet connection speed. User needs a cable modem in order to connect to the ISP's
service.

21. What is Satellite Internet access?

Satellite Internet provides broadband access by using a satellite dish for two-way data transmissions. It
is usually used in places where terrestrial Internet services such as dial-up, DSL or cable Internet services
are not available, such as rural or remote areas.

22. What is wireless broadband access?

Wireless broadband provides Internet access in areas not covered by regular "wired" Internet service, or
for people who are traveling. The more mobile version, mobile wireless broadband, is available through
a wireless broadband card (or ‘Air-Card’) that is either inserted into a computer's USB port, or PC or
Express card slot, or built-in to the computer. Service providers for such mobile wireless broadband
include popular cell phone companies such as DTAC or TRUE. Newer ‘Smartphones’ and tablet
computers such as the IPAD and Android tablets may have 3G or 4G technology built into the devices.

Definition of: TCP/IP

(Transmission Control Protocol/Internet Protocol) A communications protocol developed under contract
from the U.S. Department of Defense to internetwork dissimilar systems. Invented by Vinton Cerf and
Bob Kahn, this de facto Unix standard is the protocol of the Internet and the global standard for local
area networks and wide area networks, the major exception being the traditional networks of the
telephone companies. However, telephone companies that deploy voice over IP (VoIP) networks are, in
fact, using TCP/IP as well.

TCP/IP is commonly referred to as just "IP," which is the network layer of the protocol (see illustration
below). The terms "TCP/IP network" and "IP network" are synonymous.

Reliable and Unreliable Modes of Delivery
The TCP/IP suite provides two transport methods. TCP ensures that data arrive intact and complete,
while UDP just transmits packets. TCP is used for data that must arrive in perfect form, and UDP is used
for real-time applications such as voice over IP (VoIP) and videoconferencing, where there is no time to
retransmit erroneous or dropped packets.

IP Makes It Routable
TCP/IP is a routable protocol, and the IP network layer in TCP/IP provides this capability. The header

prefixed to an IP packet contains not only source and destination addresses of the host computers, but
source and destination addresses of the networks they reside in. Data transmitted using TCP/IP can be
sent to multiple networks within an organization or around the globe via the Internet, the world's
largest TCP/IP network.

The IP Address Identifies Everything
Every node in a TCP/IP network requires an IP address (an "IP") which is either permanently assigned or
dynamically assigned at startup.

The Internet protocol suite is the set of communications protocols used for the Internet and similar
networks, and generally the most popular protocol stack for wide area networks. It is commonly known
as TCP/IP, because of its most important protocols:Transmission Control Protocol (TCP) and Internet
Protocol (IP), which were the first networking protocols defined in this standard. It is occasionally known
as the DoDmodeldue to the foundational influence of the ARPANET in the 1970s (operated by DARPA,
an agency of the United States Department of Defense).

TCP/IP provides end-to-end connectivity specifying how data should be formatted, addressed,
transmitted, routed and received at the destination. It has four abstraction layers which are used to sort
all Internet protocols according to the scope of networking involved. From lowest to highest, the layers
are:

1. The link layer contains communication technologies for a local network.

2. The internet layer (IP) connects local networks, thus establishing internetworking.

3. The transport layer handles host-to-host communication.

4. The application layer contains all protocols for specific data communications services on a
process-to-process level. For example, HTTP specifies the web browser communication with a
web server.

TCP/IP Overview
Introduction to TCP/IP Networking .

Network Model

TCP/IP Terms

Host Names

Internet Addresses

Subnet Addresses

Internet Addresses to host name mapping

Quiz# 1

Routing

TCP/IP Daemons

TCP/IP Information files

TCP/IP Local Information files

ifconfig

mkhosts

route

Quiz# 2

TCP installed links

Internet Services

Common internet services error messages

Trouble shooting commands

ping

netstat

Trouble shooting Techniques .

Introduction to TCP/IP
What is TCP/IP?

Two separate protocols, independent of each other

TCP

Transmission Control Protocol, defines the protocol for one host (host application) to talk to another.

Layer four of the OSI/ISO model. TCP is connection oriented. Uses PAR (positive Ack with

re-transmission). Treats data as a stream.

IP

Internet Protocol, defines the protocol that gateways use to identify networks, and paths to networks
and

hosts. Handles the routing of data between networks. Layer three of the OSI/ISO model. IP is a

connectionless protocol Treats all data as datagrams.

UDP

User Datagram Protocol, Treats data as a message, and sends packets. Unreliable, connectionless

protocol. Has less overhead than the connections of TCP

ISO/OSI Network Model
OSI

Open Systems Interconnection Reference Model

First proposed by the:

ISO

International Standards Organization

The model is a theoretical model and most network implementations do not follow it exactly, TCP/IP

really has less "layers"

TCP Communication requirements

For a message to be "sent" (no guarantee that it gets there), three steps are accomplished:

1. Hostname to internet address conversion

2. Local or remote network decision

3.Local - Internet to physical address translation; Remote - Next hop gateway address

Last, Gateway internet address to physical address translation.

TCP/IP Vocabulary
Host

An entity which communicates over a network (i.e., a node)

Ethernet address

A 48 bit address built into the hardware of the ethernet controller by the manufacturer

Host Names

Each host must have a unique name on the network. They can be just names, or use the

hierarchical domain naming scheme

Internet address (IP address)

Four numbers in the range 0 - 255 separated by periods

Used to universally identify computers throughout the network, internet, or INTERNET

Router node (gateway)

A node that performs routing services between two networks of similar network protocol, often

selectively

Gateway node (router)

A node that perform routing between two networks of dis-similar network protocol types

Host Names
Each host name in a network must be unique

Easy in small networks, more difficult in large networks, impossible in the INTERNET, without some

control

Host names:

can be up to 32 characters (12)

can contain a-z, A-Z, 0-9, ., _, -

cannot contain # or spaces

must begin with an alphabetic character

Domain naming system (DNS)
Introduced to assure unique naming, and eases the administration of the naming database. Tree

structured. Requires the use of named

Usually three levels of domains, can be more

Top level, fixed, describes a category of institution:

COM Commercial

EDU Educational

GOV Government

MIL Military government

NET Changeover paths

ORG Non-profit

XX Two letter country codes

Second level domains, usually represent a whole organization. Assigned (approved) by SRI-NIC

Third and below, represent organizational departments or subdivisions within an organization

tomvc@os.rd.apollo.com fredm@cbdat.mit.edu

Internet Addresses (IPV 4)
(This is for IPV 4 – We will consider IPV 6 later)

An internet address has two fields

Left field, is the network number

Right field, is the host number

An internet address is 32 bits long

Consist of four octets (8-bit bytes), each octet defines either a network or host on that network

The network portion is assigned by NIC, the host portion is assigned locally (if you will never go on the

INTERNET, you may pick a network portion)

0 in the network portion is reserved for the default route

127 network is reserved for local loopback, or local host

0 in the host portion is reserved for this network

255 in the host portion is reserved for broadcast packets (BSD4.3) 0 was used for broadcast packets

under BSD4.2 and older

Field sizes

How many bits are used for network numbers, and how many are used for host numbers depends upon

the needs of the network

This also defines the type of address

Type Class A N.H.H.H

1.0.0.1 to 126.254.254.254 (126 networks, 16M hosts)

0 7 Bit network 24 Bit Host

It is nearly impossible to get assigned a class A address

Type B Class N.N.H.H

128.1.0.1 to 191.255.254.254 (16K networks, 65K hosts)


Most sites with class B networks use the first host address byte for local subnets

Type C Class N.N.N.H

192.1.1.1 to 223.255.255.254 (2M networks, 254 hosts)


Type D&E N.N.N.H

224.1.1.1 to 255.255.255.254

Reserved for multicast and experimental purposes

Subnet Addresses

Subnets allow you to present a simple address to the "rest of the world", yet divide your network

logically into groups of administrative, physical, or organizational control

Subnets are administered locally

The internet address doesn’t change, just how tcp/ip interprets the address

Using a netmask value, you tell tcp/ip to use a portion of the host address as a subnet address instead

(thenetmask is an argument to the ifconfig command)

A sample type B address subnetted:

128.1.0.1 to 191.254.254.254 (16K networks, 65K hosts)

Type B: N.N.H.H


Subnetted Type B2: N.N.S.H

10 14 Bit network 16 Bit Subnet 8 Bit Host

Internet Subnetted Addresses

Supernets
A supernet is a collection of smaller networks. Supernetting is a technique of using the netmask to

aggregate a collection of smaller networks into a supernet. This technique is particularly useful for class

C networks. A Class C network can only have 254 hosts. This can be too restrictive for some companies.

For these companies, a netmask that only contains a portion of the network part can be applied to the

hosts in these class C networks to form a supernet.

This supernetnetmask should be applied to those interfaces that connect to the supernet using the

ifconfig command. For example, a host can configure its interface to connect to a class C supernet,

192.6, by configuring an IP address of 192.6.1.1 and a netmask of 255.255.0.0 to its interface.

Internet Addresses to host name mapping
/etc/hosts file

Provides static mapping of addresses to host names. Works fine in small to medium size networks, as

network size increases, the complexity of upkeep of this file increases, as does lookup time.

/etc/mkhosts (Obsolete)

Creates a hashed set of hosts files for quicker lookup by TCP if named is not used (hosts.pag and

hosts.dir)

NIS (Yellow Pages)

Replaces /etc/hosts lookups

/etc/named

Replaces /etc/hosts lookups

Provides a dynamic method of mapping domain names to IP (Internet) addresses

Talks to other nameds to resolve names outside of it’s area of authoritative (local) control

Each named only knows about names in it’s local area of authoritative control

Recommended for large internets, internets with multiple areas of administrative control, and always

when on the INTERNET (arpanet)

Routing
Routing is the process by which a packet is directed through the internet between its source and

destination

Two types of routing information, static and dynamic. Static works for small fixed internets, but requires

that the configuration not change, and that the administrator know the configuration of all networks
this

network will talk to.

/etc/route

A command that installs a static route to a network in the nodes routing tables, by describing the host to

send packets to, for a particular network. (send packets to host c to reach network b)

/etc/routed

Performs dynamic routing by contacting other hosts running routed to determine the actual network

topology. A bit of a resource hog, but good when the topology changes, or the external topology is

unknown

/usr/sbin/gated

Replacement for routed, used on newer UNIX boxes instead of routed.

Usually a combination of both is used in an internet, local nets static, unknown network packets are sent

to a host running routed or gated.

Quiz #1
1. TCP defines the protocol for communication between _______.

2. IP defines the protocol for communication between _______.

3. TCP is a connection oriented protocol. True___ False ___

4. IP is a connection oriented protocol. True___ False ___

5. The 48-bit ethernet address is used for ____________________

6. The above numbers are used to: __________________________________________________

7. There are _____ bits, represented by four ________ in an internet address

8. An internet address is broken down into two sections. List them. _________________________

_________________________

9. What determines how many bits are used for each section?

___________________________________________________

10. What is the Domain Naming Server used for?

___________________________________________________

11. What is the purpose of the hosts.dirand hosts.pagfiles?

___________________________________________________

All network ports in use

You either need more psuedotty’s, or the existing ones are corrupt. To see how many exist, % ls

/dev/*typ*

To create, use the /etc/crpty command

Connection refused

The tcp connection to the remote host is good! The remote host was not running the desired service

daemon, or inetd, or inetd does not have that service enabled

Connection reset by peer

Network timeout

Connection timed out

Check to see if remote host tcpd is running, and check routes to host

Connection dead

Check if remote host crashed, or switched out

Network unreachable

Check for entry of network, and routes to network

Unknown host

Check /etc/hosts, or named

Unknown service

Check /etc/services, and /etc/protocols files

ping

netstat

lanscan

landiag

Trouble-shooting Techniques
Using ping

Ping the local host, try loopback, internet address, and host name. If the internet address works and

hostname doesn’t, the problem is in naming resolution.

Ping a host on this net, using internet address, then host name

Ping the gateway host

Ping farther towards the unreachable destination, the problem may lie in another networks routes, not

yours

Using route

It is possible to add, delete or change the routes known to this host

Using netstat

Use -T to get all info

Use -rn to get routing + address info, shows status of routes

Use -ag to see active connections, and gateway used

Use -i to see condition of interfaces, could be hardware problem

Using ifconfig

Use with interface argument only to see how an interface is currently configured

Sample Network:

Below is for REFERENCE only – You do not need to read unless you would like a
detailed understanding. You can ignore the second quiz as well.

TCP/IP Daemons
/etc/tcpd (Obsolete, functions now performed by kernel)

TCP/IP daemon. Initializes internal tables required by the protocols supported by TCP/IP, and enables a

node’s BSD socket call interface. Found on some systems, not on others. Many systems required a

kernel edit to enable networking

routed

Daemon which manages the network routing tables.

Normally only run continuously on gateways, on non-gateways it is invoked with the -h option to exit

once routing is stable. Not used at all in small stable networks

gated

Similar to routed, but supports more protocols

named

Name server daemon that provides Domain name and host name to internet address resolution,
replaces

/etc/hosts lookup

inetd

A super daemon, invokes internet services when needed:

telnetdftpdrexecd

rlogindetc/rshdtftpd

ntalkdcomsatfingerd

TCP/IP Information files
Files that are usually the same on all hosts in the same network

/etc/hosts

Relates host names and aliases to their Internet addresses

/etc/networks

Associates Internet network numbers with network names for all accessible networks, not needed.

/etc/gateways

Resides on gateway host. Or resides on administrative host with links from all gateway hosts

Only needed in networks that contain a gateway that does not support RIP (Routing Information

Protocol) and cannot run routed

Contains static routes loaded into routed’s routing tables

/etc/hosts.equiv (or $HOME/.rhosts)

Lists equivalent hosts for rlogin/telnet.... purposes (allows login without password)

/etc/resolv.conf

Contains information needed by named

TCP/IP Local Information files

Files that are often different on each host depending on network function

/etc/inetd.conf

Contains configuration information used by inetd to determine what services inetd will provide (telnet,

ftp, tftp)

/etc/rc.local or /etc/*net* or /etc/rc.config.d/*net*

Startup file for local tcp/ip daemons, network data, config commands, and miscellaneous network

commands

/etc/protocols

Contains valid protocols used by services on local host (ip, tcp, udp) (should not need editing)

/etc/services

Contains valid services for local host (finger, whois) (often needs editing)

All name server data base files

TCP Admin commands
/etc/arp

Address resolution display and control program.

Displays and modifies Internet to Ethernet address translation tables. Used to enter in this nodes
address

map, the ip address and ethernet address pair of hosts that do not support ARP (most do).

[/usr]/bin/hostname

Utility to display and modify hostname.

ifconfig

Program to assign internet addresses to a network interface.

ping spray

Utility which allows TCP to determine which hosts and gateways are still operative by eliciting an

echo_response from them

/[usr/sbin|etc]/route

Program to manually manipulate, and list the network routing tables.

hostns or hosts_to_named

Program to convert /etc/hosts to format required by name server (/etc/named)

htable

Program to convert NIC standard host tables and local host tables to format required by network library

routines. (/etc/hosts, /etc/gateways, /etc/networks)

gettable

Program to obtain NIC standard host tables

nshost

Program to convert name server config files to /etc/hosts format

routed

NAME

routed - network routing daemon

SYNOPSIS

routed [ -g ] [ -s ] [ -q ] [ -t ] [ -n ] [ -f ] [ -h ] [logfile ]

DESCRIPTION

The routed daemon is invoked at boot time to manage the network routing tables. When routed is

started, it uses the SIOCGIFCONF ioctl(2) to find those directly connected interfaces configured into

the system and marked "up" (the software loopback interface is ignored). If multiple interfaces are

present, it is assumed that the host will forward packets between networks. routed then transmits a

request packet on each interface. When a request packet is received, routed formulates a reply based
on

the information maintained in its internal tables. The response packet generated contains a list of
known

routes, each marked with a "hop count" metric (a count of 16, or greater, is considered "infinite"). The

metric associated with each route returned provides a metric relative to the sender.

OPTIONS

-g This flag is used on internetwork routers to offer a route to the "default" destination. This option is

typically used on a gateway to the Internet, or on a gateway that uses another routing protocol whose

routes are not reported to other local routers.

-s Forces routed to supply routing information whether it is acting as an internetwork router or not. This

is the default if multiple network interfaces are present, or if a point-to-point link is in use.

-q This option is the opposite of the -s option. With this option, a host runs the Routing Information

Protocol. It listens for broadcast updates but does not broadcast. The -q option is recommended for all

non-gateway hosts.

-tIf the -t option is specified, all packets sent or received are printed on the standard output. In addition,

routed will not divorce itself from the controlling terminal, so that interrupts from the keyboard will kill

the process.

gated

gated [-c] [-n] [-ttrace_options] [-f config_file] [trace_file]

gated is a routing daemon that handles the RIP, BGP, EGP, and HELLO routing protocols. The gated

process can be configured to perform all routing protocols or any combination of the four (see

WARNINGS below).

-c Parse the configuration file for syntax errors then exit. If there were no errors, leave a dump file in

/usr/tmp/gated_dump. Running gated does not require super-user privilege when using the -c option,
but

gated may not be able to read the kernel’s routing table unless it is run as super user. The -c option

implies -tierk.

-n Do not modify the kernel’s routing table. This option is used for testing gated configurations with

actual routing data.

-ttrace_optionsEnable trace flags on startup. trace_options can include one or more of the following

values:

A all P protocol

i internal u update

e external R RIP

k kernel H hello

r route C icmp

m mark p EGP

tnostamp B BGP

-f config_fileUse an alternate configuration file. By default, gated uses /etc/gated.conf.

trace_file Trace file in which to place trace information.

SIGHUP Re-read configuration.

SIGINT Snapshot of current state.

The current state of all gated tasks, timers,

protocols, and tables are written to

/usr/tmp/gated_dump.

SIGTERM Graceful shutdown.

SIGUSR1 Toggle tracing.

NINGS

At HP-UX 8.07, the shipped version of gated did not require a config file. At 9.01 and above it does, or

gated dies.

Also, gated is known for expiring it’s own interface, but this can be fixed with an entry in the config file.

Here is a sample of the config file options most commonly used, use man gated.conf for the complete

list:

gated.conf -

gated configuration file syntax

The gated config file consists of a sequence of statements terminated by a semicolon (;).

Statements are composed of tokens separated by white space, which can be any combination of

blanks, tabs and new-line characters.

Comments:

Starting with a # character and running to the end of the

line.

‘‘C’’ style, which starts with a /* and continues until it

reaches */.

Statement Classes:

There are four (6) classes of statements. The four listed here must be specified in order:

Definition, protocol, static routes, control

/etc/gated.conf

Definition statements

These statements specify options, the autonomous system, martian networks, and interface

options.

interfaceinterface_listinterface_options ;

Sets interface options on the specified interfaces. An interface list is all or a list of interface names

metricmetric

Set the interface metric for this interface. This metric is used by RIP and HELLO.

Specifying the metric here overrides for internal use, but does not change the metric set by

ifconfig.

preferencepref

Sets the preference for routes to this interface.

passive

Prevents gated from deleting the route to this interface if it is believed to be down due to routing

information not received.

martians {

martian_list

};

Defines a list of martian addresses about which all routing information is ignored.

Protocol statements

These statements enable or disable protocols and set protocol options.

Routing Information Protocol (RIP):

ripyes|no|on|off|quiet|pointopoint|supplier [ {

preferencepreference ;

defaultmetric metric ;

interfaceinterface_list [noripin] [noripout] ;

...

trustedgatewaysgateway_list ;

sourcegatewaysgateway_list ;

}];

If yes or on is specified, RIP assumes quiet if there is only one interface and supplier if there

are more than two or more.

quiet specifies that no RIP packets are to be generated. supplier specifies that RIP packets

are to be generated. pointopoint specifies that RIP packets are to be sent only to gateways

listed in the sourcegateways clause. If the RIP clause is not specified, the default is on.

The default metric is 16, the default preference is 100.

HELLO Protocol:

helloyes|no|on|off|quiet|pointopoint|supplier [ {



interfaceinterface_list [nohelloin] [nohelloout] ;

...


sourcegatewaysgateway_list ;

}];

If yes or on is specified, HELLO assumes quiet if there is only one interface and supplier if

there are two or more.

quiet specifies that no HELLO packets are to be generated. supplier specifies that HELLO

packets are to be generated. Pointopoint specifies that HELLO packets are to be sent only to

gateways listed in the sourcegateways clause. If the HELLO clause is not specified the

default is off. The default metric is 30000, the default preference is 90.

Exterior Gateway Protocol (EGP):

egpyes|no|on|off [ {



packetsizemaxpacketsize ;

group [asinautonomous_system]

[asoutautonomous_system]

[maxup number]

[preference preference] {

neighbor host

[metricout metric]

[nogendefault]

[acceptdefault]

[propagatedefault]

[gateway gateway]

[interface interface]

[sourcenet network]

[minhellomin_hello]

[minpollmin_poll]

;

...

};

...

}];

packetsize specifies the size, in bytes, of the largest EGP packet to be accepted or sent. A

group lists a group of EGP peers in one autonomous system. maxup specifies the maximum

number of peers to be maintained in the Up state. acceptdefault and propagatedefault tell

gated to accept or propagate the default network (0.0.0.0) in updates exchanged with an EGP

neighbor. If not specified, the default network is ignored when exchanging EGP updates.

sourcenet specifies the network to query in EGP Poll packets, this is normally the shared

network. The minimum acceptable EGP hello and poll intervals can be specified with the

minhello and minpoll arguments, respectively. These are both specified as a time in seconds,

minutes:seconds, or hours:minutes:seconds. Any number of group clauses can be specified

containing any number of neighbor clauses. Any parameters from the neighbor clause can be

specified in the group clause to provide defaults for the group.

The default metric is 255, the default preference is 200.

Border Gateway Protocol (BGP ):

Note that although BGP is available with this version of gated, it is currently not supported

by HP.

bgpyes|no|on| off [ {



peer host

[linktype [up|down|horizontal|internal]]

[metricout metric]

[asinautonomous_system]

[asoutautonomous_system]

[nogendefault]

[gateway gateway]

[interface interface]

;

...

}];

peer specifies the address of each BGP peer. A linktype internal is assumed if the neighbor’s

autonomous system is the same as my autonomous system. Otherwise linktype horizontal is

assumed.

The default metric is 65535 and the default preference is 150 for external BGP and 250 for

internal BGP.

Redirect (ICMP):

redirectyes|no|on|off [ {


interfaceinterface_list [noicmpin] ;


}];

Controls whether gated makes routing table changes based on ICMP redirects when not

functioning as a router. When functioning as a router (i.e. any interior routing protocols

(RIP, HELLO) are participating in routing on any interface, ICMP redirects are disabled.

When ICMP redirects are disabled, gated must actively remove the effects of redirects from

the kernel as the kernel always processes ICMP redirects. The default preference is 20.

Static route statements

Static routes are defined by route statements.

static {

destination gateway gateway [preference

preference] ;

...

destination interface interface [preference

preference] ;

...

};

Any number of static statements can be specified, each containing any number of static route

definitions. The first form defines a static route through a gateway. The second defines a static

interface route which is used for primitive support of multiple networks on a single interface.

The preference for static routes defaults to 50.

Control statements

Control statements define routes that are accepted from routing peers and routes that are

propagated to those peers. The clauses define which hosts to accept routes from, and propagate

routes to .

Luckily there are examples provided in the HP-UX 9.XX directory:

/etc/newconfig/gated/conf

Better still, this is what you will probably use on most hosts and gateways in a local internet:

rip yes ;

As well as some static routes possibly.

Sample /etc/gated.conf

# Config file gated on Achilles

# Gated Version 2.0.1.2

traceoptions internal external route rip update ;

interface all passive ; # don’t time out my interfaces!

#rip yes ;

rip supplier {

interface fddi0 noripout ;

#no rip onto CTD FDDI/don’t want to be a router

trustedgateways 130.202.64.5 ; # trust sungate

};

# need some static routes

static {

# default is via Sungate

default gateway 130.202.64.5 ;

# XMP via FDDI and Network Systems Corp

146.137.5.0 gateway 146.137.5.129 ;

};

propagate proto rip interface ie2 {

proto static metric 1 {

announce default ;

};

};

propagate proto rip interface ie0 {

proto direct {

announce 130.202.60 metric 1 ;

# announce path to VISNet

};

};

named

NAME

named - Internet domain name server

SYNOPSIS

named [ -d debuglevel ] [ -p port# ] [{ -b } bootfile ]

DESCRIPTION

Without any arguments, named will read the default boot file /etc/named.boot, read any initial data and

listen for queries.

OPTIONS

-d debuglevel Print debugging information. A number after the "d" determines the level of messages

printed.

-p port# Use a different port number. The default is the standard port number as listed in /etc/services.

-b Use an alternate boot file. This is optional and allows you to specify a file with a leading dash.

Any additional argument is taken as the name of the boot file. The boot file contains information about

where the name server is to get its initial data. If multiple boot files are specified, only the last is used.

EXAMPLE

The following example shows a boot file:

; boot file for name server

directory /usr/local/domain

; type domain source host/file backup file

cache .root.cache

primary Berkeley.EDU berkeley.edu.zone

primary 32.128.IN-ADDR.ARPA ucbhosts.rev

secondary CC.Berkeley.EDU 128.32.137.8 128.32.137.3 cc.zone.bak

secondary 6.32.128.IN-ADDR.ARPA 128.32.137.8 128.32.137.3 cc.rev.bak

primary 0.0.127.IN-ADDR.ARPA localhost.rev

forwarders 10.0.0.78 10.2.0.78

; slave

FILES

/etc/named.boot name server configuration boot file

/etc/named.pid the process id

/usr/tmp/named.run debug output

/usr/tmp/named_dump.db dump of the database

/usr/tmp/named.stats name server statistics data

Configuration files read by /etc/named.boot:

/etc/named.ca

/etc/named.hosts

/etc/named.local

/etc/named.rev

inetd

NAME

inetd - internet "super-server"

SYNOPSIS

/etc/inetd[ -d ] [ configuration file ]

DESCRIPTION

Run at boot time by rc files. It listens for connections on certain internet sockets. When a connection is

found on one of its sockets, it decides what service the socket corresponds to, and invokes a program to

service the request. Essentially, inetd allows running one daemon to invoke several others, reducing
load

on the system.

Upon execution, inetd reads its configuration information from a configuration file which, by default, is

/etc/inetd.conf. inetd rereads its configuration file when it receives a hangup signal, SIGHUP. (kill -hup

pid) The fields of the configuration file are as follows:

service name socket type protocol wait/nowait user

server program server program arguments

Example:

telnet stream tcpnowait root /etc/telnetdtelnetd

/etc/hosts

NAME

hosts - host name database

DESCRIPTION

The hosts file contains information regarding the known DARPA Internet hosts with which your

Domain node can communicate (usually via TCP/IP). For each host, a single line should be present with

the following information:

Internet address official host name aliases

A "#" indicates the beginning of a comment.

When using the name server named(8), this file provides a backup when named is not running. For the

name server, it is suggested that only a few addresses be included in this file. These include address for

the local interfaces that ifconfig(8C) needs at boot time and a few machines on the local network.

Host names may contain any printable character other than a field delimiter, newline, or comment

character.

EXAMPLE

The example below is for the network shown on an earlier page in the handout

# /etc/hosts Rev Date 6/9/90 by FAM

203.1.12.3 escort lynx.crp.fame.com

203.1.12.2 nine44 speedo

203.1.12.1 kerma1

151.2.3.1 cj5 trucker #gateway

151.2.3.2 beartooth

151.2.3.3 nacra5

151.2.3.4 kerma1 #gateway

192.2.2.1 giant

192.2.2.2 cj5

127.0.0.1 localhost

##!!!! NOTE: Do not use any leading spaces, or blank lines.

#Do not "pretty-up" the columns with leading "0"’s

/etc/networks

NAME

networks - network name database

DESCRIPTION

The /etc/networks file contains information regarding the known networks which comprise the DARPA

Internet. For each network a single line should be present with the following information:

official network name network number aliases

A "#" indicates the beginning of a comment

Network numbers may be specified in the conventional "." notation. Network names may contain any

printable character other than a field delimiter, newline, or comment character.

EXAMPLE

The example below is for the network shown on an earlier page in the handout

#/etc/networks Rev Date 5/10/90 by FAM

net2 203.1.12 ring2

net3 151.2 ethernet

net1 192.2.2 ring1

local 127.0.0

Network startup file overview

All startup files, no matter the system, must do the following:

Set the hostname

Start the tcpd if the system is not kernel based

Configure the lan interface with ifconfig

Establish the routing method, and invoke it:

routed/gated/route

Then any other tools and commands can be started:

inted

named

X

NIS

NFS

mail

snmpd

arp

syslogd

rwhod

timed

nmconfig

Sample HP-UX netlinkrc file (9.01)

#! /bin/sh

# @(#)netlinkrc: $Revision: 1.6.109.7 $ $Date: 92/07/13 08:21:12 $

# $Locker: $

# net_init flag is used for Instant Ignition. If net_init is set,

# thennetlinkrc return "exit 1". In order for Instant Ignition

# to work correctly, netlinkrc needs to check the STATUS variable

# after each program or scripts it calls.

net_init=0

if [ -f /etc/clusterconf ]

then

ROOTSERVER=‘/bin/cnodes -r‘

NODENAME=‘/bin/cnodes -m‘

DOMAIN=‘/bin/cnodes -r‘

ORGANIZATION=diskless

else

ROOTSERVER=‘hostname‘

NODENAME=$ROOTSERVER

DOMAIN=‘/bin/uname -n‘

ORGANIZATION=standalone

fi

# Start logging daemon *before* any other networking initialization.

# See nettl(1m) for more information.

/etc/nettl -start

STATUS=$?

if [ ! $STATUS -eq0 ]

then

net_init=1

fi

# Remove the existing /etc/netstat_data file. The first time

# netstat is executed, a new /etc/netstat_data file will be

# created.

/bin/rm -f /etc/netstat_data

# Initialize networking interfaces.

# (STEP 1)

# The "case $NODENAME" construct below allows each node in a diskless cluster

# to execute node specific calls if necessary. Add entries to

# the case construct for specific nodes in the diskless cluster only if

# needed. For example, if a specific node has more than one LAN interface,

# the node must execute separate commands for each of the interfaces.

# NOTE: If the ifconfig command line does not specify a subnet mask,

# the subnet mask defaults to the network mask.

# It is not necessary for both encapsulation methods to be turned on

# for the LAN Interface. For further explanation see lanconfig(1m)

#

# The loopback interface must be explicitly configured for each address

# family of interest. The following command assumes that the hostname

# has already been set and is mapped to an IP Address in /etc/hosts.

#

# SEE ALSO: ifconfig(1m), lanconfig(1m)

case $NODENAME in

*) /etc/ifconfig lan0 inet‘hostname‘ up

STATUS=$?


then

net_init=1

fi

/etc/lanconfig lan0 ether

STATUS=$?


then

net_init=1

fi

;;

esac

/etc/ifconfig lo0 inet 127.0.0.1 up

STATUS=$?


then

net_init=1

fi

#

# Initialize network routing.

#

# (STEP 2) (OPTIONAL, FOR NETWORKS WITH GATEWAYS ONLY)

#

# The route(1m) command manipulates the network routing tables.

# The "case $NODENAME" construct below allows each node in a diskless

# cluster to execute node specific route calls if necessary. Add entries

# to the case construct for specific nodes in the diskless cluster if needed.

# The STATUS checking is for Instant Ignition.

##

# SEE ALSO: route(1m), routing(7)

case $NODENAME in

*) # add route commands for specific nodes here

;;

esac

#

# Initialize the network node name.

#

# (STEP 3)

#

# The nodename(1m) command assigns an NS node name to the node.

# Nodename takes an option of the form "nodename.domainname.orgname" where,

#

# nodename is the name of the local node

# domainname is the name of the domain

# orgname is the name of the organization

#

# Each name must start with an alphabetic character.

#

# It is strongly recommended that the string used for "nodename" above be

# identical to the string used as an argument to the hostname(1) command,

# which is typically invoked from the system initialization shell script

# file "/etc/rc". The NS nodename used on each node in your network needs

# to be unique within that network. The "case $NODENAME" construct below

# allows each node in a diskless cluster to execute a node specific

# nodename(1) call if necessary. Add entries to the case construct for

# specific nodes in the diskless cluster only if needed.

#

# For example,

#

# case $NODENAME in

# * ) /bin/nodename ‘/bin/uname -n‘.mydomain.myorg

# ;;

# esac

#

# sets the NS nodename for all nodes (* is the wildcard) in domain

# "mydomain" and organization "myorg".

#

# Thenodename command line below sets the nodename field to the system

# hostname, the domainname field to the rootserver’s name, and the orgname

# field to "diskless".

#

# SEE ALSO: nodename(1)

if [ -x /bin/nodename ]

then

case $NODENAME in

*) /bin/nodename ‘/bin/uname -n‘.$DOMAIN.$ORGANIZATION

STATUS=$?


then

net_init=1

fi

;;

esac

fi

#

# Start remote loop back daemon

#

if [ -f /usr/adm/rld.log ]

then

/bin/mv /usr/adm/rld.log /usr/adm/OLDrld.log

fi

if [ -x /etc/rlbdaemon ]

then

(/etc/rlbdaemon 2>&1 )> /usr/adm/rld.log

STATUS=$?


then

net_init=1

fi

fi

/bin/echo "Network Link started"

#

# Start NFS. This requires installation of the NFS product.

#

if [ -x /etc/netnfsrc ]

then

/etc/netnfsrc

STATUS=$?


then

net_init=1

fi

fi

/bin/echo "ARPA/Berkeley daemons started: c"

#

# Start the Internet daemon.

#

[ -x /etc/inetd ] && /etc/inetd&& /bin/echo "inetd c"

STATUS=$?


then

net_init=1

fi

#

# Start ARPA/BSD networking services.

#

if [ -x /etc/netbsdsrc ]

then

/etc/netbsdsrc

STATUS=$?


then

net_init=1

fi

fi

/bin/echo

#

# Do nfs mounts after inetd is running

#

if [ -x /etc/netnfsrc2 -a -f /etc/nfs.up ]

then

/etc/netnfsrc2

STATUS=$?


then

net_init=1

fi

fi

#

# Start NS networking services.

#

if [ -x /etc/netnssrc ]

then

/etc/netnssrc

STATUS=$?


then

net_init=1

fi

fi

#

# Start HP Network Management Agent

#

if [ -x /etc/netnmrc ]

then

/etc/netnmrc

STATUS=$?


then

net_init=1

fi

fi

#

# Start HP LAN Manager/X.

#

if [ -x /etc/netlmrc ]

then

/etc/netlmrc

STATUS=$?


then

net_init=1

fi

fi

#

# Start NCS. This requires installation of the NCS product.

# NCS must be started before any other NCS products are started.

#

if [ -x /etc/netncsrc ]

then

/etc/netncsrc

STATUS=$?


then

net_init=1

fi

fi

#

# Start NetLS. This requires installation of the NetLS product.

# NCS must be started before NetLS is started.

#

if [ -x /etc/netlsrc ]

then

/etc/netlsrc

STATUS=$?


then

net_init=1

fi

fi

# return exit code for Instant Ignition

if [ $net_init -eq 0 ]

then

exit 0

else

exit 1

fi

Sample HP-UX /etc/rc.config.d/netconf

# netconf: configuration values for core networking subsystems

# @(#) $Revision: 1.3.111.2 $ $Date: 95/01/25 11:35:38 $

# HOSTNAME: Name of your system for uname -S and hostname

# OPERATING_SYSTEM: Name of operating system returned by uname -s

# ---- DO NOT CHANGE THIS VALUE ----

# LOOPBACK_ADDRESS: Loopback address

# ---- DO NOT CHANGE THIS VALUE ----

# IMPORTANT: for 9.x-to-10.0 transition, do not put blank lines between

# the next set of statements

HOSTNAME="puxy"

OPERATING_SYSTEM=HP-UX

LOOPBACK_ADDRESS=127.0.0.1

# Internet configuration parameters. See ifconfig(1m), lanconfig(1m)

# INTERFACE_NAME: Network interface name (see lanscan(1m))

# IP_ADDRESS: Hostname (in /etc/hosts) or IP address in decimal-dot

# notation (e.g., 192.1.2.3)

# SUBNET_MASK: Subnetwork mask in decimal-dot notation, if different from def

# BROADCAST_ADDRESS: Broadcast address in decimal-dot notation, if different from d

# LANCONFIG_ARGS: Link-layer encapsulation methods (e.g., ieee, ether). See

# lanconfig(1m) for details.

# For each additional network interfaces, add a set of variable assignments

# like the ones below, changing the index to "[1]", "[2]" et cetera.



INTERFACE_NAME[0]=lan0

IP_ADDRESS[0]="179.102.3.2"

SUBNET_MASK[0]=""

BROADCAST_ADDRESS[0]=""

LANCONFIG_ARGS[0]="ether"

# Internet routing configuration. See route(1m), routing(7)

# ROUTE_DESTINATION: Destination hostname (in /etc/hosts) or host or network

# IP address in decimal-dot notation, preceded by the word

# "host" or "net"; or simply the word "default".

# ROUTE_MASK: Subnetwork mask in decimal-dot notation, or C language

# hexadecimal notation. This is an optional field.

# A IP address, subnet mask pair uniquely identifies

# a subnet to be reached. If a subnet mask is not given,

# then the system will assign the longest subnet mask

# of the configured network interfaces to this route.

# If there is no matching subnet mask, then the system

# will assign the default network mask as the route’s

# subnet mask.

# ROUTE_GATEWAY: Gateway hostname (in /etc/hosts) or IP address in

# decimal-dot notation. If local interface, must use the

# same form as used for IP_ADDRESS above (hostname or

# decimal-dot notation).

# ROUTE_COUNT: An integer that indicates whether the gateway is a

# remote interface (one) or the local interface (zero).

# ROUTE_ARGS: Route command arguments and options. This variable

# may contain a combination of the following arguments:

# "-f", "-n" and "-p pmtu".

# For each additional route, add a set of variable assignments like the ones

# below, changing the index to "[1]", "[2]" et cetera.



ROUTE_DESTINATION[0]="default"

ROUTE_MASK[0]=""

ROUTE_GATEWAY[0]="179.102.3.2"

ROUTE_COUNT[0]="0"

ROUTE_ARGS[0]=""

# Dynamic routing daemon configuration. See gated(1m)

# GATED: Set to 1 to start gated daemon.

# GATED_ARGS: Arguments to the gated daemon.

GATED=0

GATED_ARGS=""

# Router Discover Protocol daemon configuration. See rdpd(1m)

# RDPD: Set to 1 to start rdpd daemon

RDPD=0

ifconfig

NAME

ifconfig - configure network interface parameters

SYNOPSIS

/usr/sbin/ifconfig or /etc/ifconfig

ifconfig interface [address_family (inet)

[address[dest_addr]][parameters]]

ifconfig interface [address_family]

DESCRIPTION

ifconfig is used to assign an address to a network interface and/or configure network interface

parameters. The second format shown above displays current status.ifconfig must be used at boot time

to define the network address of each interface present on a machine.

ethernet on hpux lan0, lan1, lan2

(Use lanscanto get a list of devices)

Apollo token ring on hpux atr1

Addresses supplied can be names from the hosts/networks files or dotted decimal notation

PARAMETERS

up Mark an interface "up." This may be used to

enable an interface after an "ifconfig down."

down Mark an interface "down." When an interface is

marked "down,"the system will not attempt to

transmit messages through that interface.

trailers Request the use of a "trailer" link level

encapsulation when sending (default). If a network interface supports trailers, the system will, when

possible, encapsulate outgoing messages in a manner which minimizes the number of memory to

memory copy operations performed by the receiver. On networks that support the Address Resolution

Protocol (see arp(4P); currently, only 10 MB ETHERNET), this flag indicates that the system should

request that other systems use trailers when sending to this host. Similarly, trailer encapsulations will be

sent to other hosts that have made such requests. Currently used by Internet protocols only.

NOTE: If any host on the network is running bsd4.2, dis-able trailers on all hosts. (No effect on HP-UX)

-trailers Disable the use of a "trailer"

arp Enable the use of the Address Resolution Protocol in mapping between network level addresses and

link level addresses (default). This is currently implemented for mapping between DARPA Internet

addresses and 10MB ETHERNET addresses.

-arp Disable the use of the Address Resolution Protocol.

debug Enables extra logging to the console

-debug Default

metric n Set the routing metric of the interface to n, default 0. Higher metrics have the effect of making
a

route less favorable; metrics are counted as addition hops to the destination network or host.

debug Enable driver dependent debugging code; usually, this turns on extra console error logging.

-debug Disable driver dependent debugging code.

netmask mask (Inet only) Specify how much of the address to reserve for subdividing networks into

subnetworks. The mask can be specified as a single hexadecimal number with a leading 0x, with a

dot-notation Internet address, or with a netmask name

listed in the host table. The mask contains 1’s for the bit positions to be used for the network and
subnet

parts, and 0’s for the host part. On Apollo hosts, if you use the netmask name "defaultmask" with

ifconfig, and "defaultmask" is listed in hosts(5) with a subnet mask value, ifconfig succeeds and sets the

subnet mask to the value found in hosts. If "defaultmask" is not found in the hosts file, ifconfig still

succeeds but sets the mask to the default for the address class. For example, the default mask for a Class

C network is 255.255.255.0

netmaskicmp-request Specifies that the host should obtain its subnet mask from local gateways, using

the ICMP Address Mask Request/Reply protcol. A node will respond to this request only if it is a

gateway (that is, it has more than one network interface enabled) and if its own subnet mask was

explicity set with the "netmask mask" parameter (and it did not itself use the ICMP

request protocol). If the requesting host receives no

responses within 2 seconds, it assumes that subnets are not in use on the network. You also can enable

this ICMP Address Mask protocol by assigning the address 255.255.255.255 to the netmask name

"defaultmask" in the hosts file.

dest_addr Specify the address of the correspondent on the other end of a point to point link.

broadcast (Inet only) Specify the address to use to represent broadcasts to the network. The default

broadcast address is the address with a host part of all 1’s. If the host must interoperate with older TCP

implementations that require the 0-form IP broadcast address, specify "broadcast 0". You cannot specify

this parameter when configuring either a loopback or point-to-point interface.

The ifconfig lines used in the network depicted on page 11.

Gateway cj5(if interoperating with bsd4.2, use "broadcast 0 -trailers")

/etc/ifconfig atr0 192.2.2.2 up netmask 0xffffff00 trailers

/etc/ifconfig lo0 127.0.0.1 up

/etc/ifconfig lan0 151.2.3.1 up netmask 0xffff0000 trailers

Gateway kerma1 /etc/ifconfig atr0 203.1.12.1 up netmask 0xffffff00 trailers

/etc/ifconfig lo0 127.0.0.1 up

/etc/ifconfig lan0 151.2.3.4 up netmask 0xffff0000 trailers

Using ifconfig to check interface configuration

[135]$ /etc/ifconfig atr0

atr0: flags=43<UP,BROADCAST,RUNNING>

inet 203.1.12.2 netmask ffffff00 broadcast 203.1.12.255

# ifconfig lan0

lan0: flags=863<UP,BROADCAST,NOTRAILERS,RUNNING>

inet 179.102.3.2 netmask ffff0000 broadcast 179.102.255.255

route

NAME

route - manually manipulate the routing tables

SYNOPSIS

route [ -n ] [ -f ] [ -p pmtu ] [ cmd [ net | host ] args ]

DESCRIPTION

route is a program used to manually manipulate the network routing tables. It normally is not needed,
as

the system routing table management daemon, routed or gated, should tend to this task. When external

routers are used, a default route is often needed, the default route nost can be this host. route accepts
two

commands:

addadd a route

deletedelete a route

Routes can be displayed with the command netstat -r

COMMAND SYNTAX

All commands have the following syntax:

command [net|host] destination gateway [metric]

destination is the destination host or network

gateway is the next-hop gateway to which packets should be addressed

metric is a count indicating the number of hops to the destination.

The metric is required for add and addp commands; it must be zero if the destination is on a

directly-attached network, and nonzero if the route utilizes one or more gateways. If adding a route
with

metric 0, the gateway given is the address of this host on the common network, indicating the interface

to be used for transmission.

The optional keywords net and host force the destination to be interpreted as a network or a host,

respectively. If the route is to a destination connected through a gateway, the metric should be greater

than 0.

Add a default route as follows:

/etc/route add default gateway_name [non-zero metric]

TCP/IP software will use the default route when other routes occurring earlier in the routing table have

failed, or when there are no other possible routes.

Only the super-user may modify the routing tables.

OPTIONS

-f "Flush" the routing tables of all gateway entries. Using this option in conjunction with one of the

commands described above flushes the tables prior to the command’s application.

-n Use dot notation instead of names.

DIAGNOSTICS

add [ host | network ] %s: gateway %s flags %x

This, when returned means the specified route is being added to the tables.

delete [ host | network ] %s: gateway %s flags %x

As above, but when deleting an entry.

%s %s done

When the -f flag is specified, each routing table entry deleted is indicated with a message of this form.

Network is unreachable

An attempt to add a route failed because the gateway listed was not on a directly-connected network.

The next-hop gateway must be given.

not in table

A delete operation was attempted for an entry that wasn’t present in the tables.

routing table overflow

An add operation was attempted, but the system was low on resources and was unable to allocate

memory to create the new entry.

If static routing is used in the network from an earlier diagram in this handout, here are some
commands

that would work:

On gateway cj5

[458]$ /etc/route add net 151.2 192.2.2.2 0

add net 151.2: gateway 192.2.2.2

[459]$ /etc/route add net 203.1.12 151.2.3.4 1

add net 203.1.12: gateway 151.2.3.4

On gateway kerma1

[123]$ /etc/route add net 151.2 203.1.12.1 0

add net 151.2: gateway 203.1.12.1

[124]$ /etc/route add net 192.2.2 151.2.3.1 1

add net 192.2.2: gateway 151.2.3.1

If routed or gated is not used also, all hosts would need to have a default route set to

their respective gateways, in net1:[458]$ /etc/route add default 192.2.2.2

Quiz #2
1. When is sub-netting used? __________________________

2. How is subnetting set-up and controlled? (What command)

________________________________________________

3. What is the function of the route command? ________________

4. What is the function of the routed daemon? ________________

5. What option to routed would you use on a host node? _______

6. When would you have to edit the /etc/rc.local file?

___________________________________________________

7. When would you use the ifconfig command?

___________________________________________________

8. What service does inetd provide? ________________________

9. When must you use named? ____________________________

10. When must you use the ’broadcast 0’ argument of ifconfig?

___________________________________________________

11. When must you use the ’-trailers’ argument of ifconfig?

___________________________________________________

12. Go back to the diagram used in the first quiz and fill in the

following information:

Which nodes should be running routed, and with which options

The ifconfig command lines for each node

Show any static routes that would be helpful

Show the /etc/networks file

Internet Services
NAME

rwho- who’s logged in on local machines

SYNOPSIS

rwho [ -a ]

DESCRIPTION

The rwho command produces output similar to who, but for all machines on

the local network

NAME

telnet- user interface to the TELNET protocol

SYNOPSIS

telnet [ host [ port ] ]

DESCRIPTION

telnet is used to communicate with another host using the TELNET protocol.

NAME

rlogin- remote login

SYNOPSIS

rloginrhost [ -ec ] [ -8 ] [ -L ] [ -l username ]

rhost [ -ec ] [ -8 ] [ -L ] [ -l username ]

DESCRIPTION

rlogin connects your terminal on the current local host system lhost to the remote host system rhost.

NAME

ftp- ARPANET file transfer program

SYNOPSIS

ftp [ -v ] [ -d ] [ -i ] [ -n ] [ -g ] [ host ]

DESCRIPTION

ftp is the user interface to the ARPANET standard File Transfer Protocol (FTP). The program allows

you to transfer files to and from a remote network site.

NAME

tftp- trivial file transfer protocol

SYNOPSIS

tftp [ -g|g!|p|r|w ] localname host foreignname [mode]

DESCRIPTION

tftp is the front-end to the Trivial File Transfer Protocol. It enables you to copy files among internet

hosts without remote user-level access.

NAME

rcp- remote file copy

SYNOPSIS

rcp [ -p ] file1 file2

rcp [ -p ] [ -r ] file ... directory

DESCRIPTION

The rcp command copies files between machines. Each file or directory argument is either a remote file

name of the form rhost:path or a local filename containing no ":"

NAME

remsh- remote shell

SYNOPSIS

rsh host [ -l username ] [ -n ] command

host [ -l username ] [ -n ] command

DESCRIPTION

rsh connects to the specified host, and executes the specified command. rsh copies its standard input to

the remote command, the standard output of the remote command to its standard output, and the

standard error of

the remote command to its standard error. Interrupt, quit and terminate signals are propagated to the

remote command; rsh normally terminates when the remote command does.

NAME

talk- talk to another user

SYNOPSIS

talk person [ttyname]

DESCRIPTION

talk is a visual communication program that copies lines from your terminal to that of another user.

If you wish to talk to someone on your own machine, then person is just the person’s log-in name. If you

wish to talk to a user on another host, then person is of the form

user@host

All network ports in use

You either need more psuedotty’s, or the existing ones are corrupt. To see how many exist, % ls

/dev/*typ*

To create, use the /etc/crpty command

Connection refused

The tcp connection to the remote host is good! The remote host was not running the desired service

daemon, or inetd, or inetd does not have that service enabled

Connection reset by peer

Network timeout

Connection timed out

Check to see if remote host tcpd is running, and check routes to host

Connection dead

Check if remote host crashed, or switched out

Network unreachable

Check for entry of network, and routes to network

Unknown host

Check /etc/hosts, or named

Unknown service

Check /etc/services, and /etc/protocols files

ping

netstat

lanscan

landiag

Trouble-shooting Techniques
Using ping

Ping the local host, try loopback, internet address, and host name. If the internet address works and

hostname doesn’t, the problem is in naming resolution.

Ping a host on this net, using internet address, then host name

Ping the gateway host

Ping farther towards the unreachable destination, the problem may lie in another networks routes, not

yours

Using route

It is possible to add, delete or change the routes known to this host

Using netstat

Use -T to get all info

Use -rn to get routing + address info, shows status of routes

Use -ag to see active connections, and gateway used

Use -i to see condition of interfaces, could be hardware problem

Using ifconfig

Use with interface argument only to see how an interface is currently configured

Tcp/ip

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