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Wind River SystemsTornado Training Workshop © Copyright Wind River Systems 12-1

Chapter

12

Networking

Introduction

VxWorks Network Configuration

Routing Protocols

Remote Access Services


Networking

12.1 Introduction


Routing Protocols


Network Stack


Available Network Facilities


Network Protocols

• Machines on a network must agree to exchange data in

some standard way.

• Internet protocol suite (also called TCP/IP) provides

system independent protocols.

• VxWorks provides an implementation of TCP/IP

protocol suite based on the 4.4BSD release

• Features include:

● Increased configurability and scalability

● MUX layer

● Support for contemporary Internet features

• Internet protocols are standardized through Requests for Comments

(RFCs) circulated by the Internet Engineering Task Force (IETF). These

RFCs are the authoritative guide to how these protocols should work.

RFCs can be found at www.ietf.org/rfc/.

• Good books on network programming:

● Unix Network Programming, volume I, 2nd ed. (Stevens), 1997.

● Internetworking with TCP/IP volume III, 2nd ed. (Comer), 1996.

• For an overview and internals of network protocols:

● TCP/IP Illustrated, Volume 1 (Stevens), 1994.● TCP/IP Illustrated, Volume 2 (Wright and Stevens), 1995.

● Internetworking with TCP/IP volume I, 3rd ed. (Comer), 1995.

● Internetworking with TCP/IP volume II, 2nd ed. (Comer), 1994.

● The Design and Implementation of the 4.4 BSD UNIX Operating System(McKusick et. al.), 1996.


Network Components

Shared MemoryNetwork

SLIP/PPPEthernet

SocketszbufAPI

TCP UDP

rlogin telnet rsh ftpTornado

tgtsvrNFS

RPC

IP

netDrv

MUX

• The MUX layer is a thin API layer that decouples network interface

drivers from the network protocol.

• IP, the Internet Protocol, is responsible for point-to-point delivery of

datagrams.

• TCP, Transmission Control Protocol, and UDP, User Datagram Protocol,

are both transport level protocols. UDP is a lightweight datagram

delivery service, and TCP is a full-featured connection-based protocol

which provides reliable data transport.

• Berkeley sockets, zbuf sockets, and RPC are supported network

programming APIs.

• The zbuf Sockets API uses buffer loaning to speed up network

communication.


Network Scalability• Selective inclusion of core TCP/IP networking

protocols is provided.

• TCP/IP parameters can be set by setting properties of

individual components. Examples: TCP Connection

Timeout, IP Time-to-Live value, TCP/UDP receive and

send buffer sizes, and tuning of internal buffers. (See

VxWorks Network Programmer’s Guide.)

• ICMP (Internet Control Message Protocol), configurable separately

from IP, handles error and informational messages at the IP layer. Two

such messages are echo reply (used by ping()) and redirect (used to repair

bad routing entries).

• IGMP (Internet Group Management Protocol) is used by hosts and

routers to support multicasting.

• The network library support component includes the library netLib which

provides support for network drivers through the system task tNetTask.

• Internal buffering is in the form of pre-allocated memory pools of fixed-

size mBlks and clBlks. The size and number of blocks in these pools can

be changed to tune stack performance, but be sure to read the VxWorksNetwork Programmer’s Guide description first!


Network Services

• VxWorks network services include:

● DHCP/BOOTP

● Simple Network Time Protocol (SNTP)

● DNS resolver

● Dynamic Routing (RIPv1/RIPv2/OSPF)

● rlogin/telnet

● Remote command execution

● Remote file access

● Multicasting, including IGMP

• User can build other network services as needed.

• To use these network services the appropriate components must be

included in the VxWorks image.

• DHCP, Dynamic Host Configuration Protocol, and BOOTP are two

protocols supporting booting a target from a remote boot server. DHCP

will be discussed in in this chapter.

• DNS, Domain Name Service, allows a target to look up remote hosts by

name. DNS will be discussed in this chapter.

• A number of optional networking products are available, including:

● WindWeb server (HTTP server)

● SNMP

● STREAMS

● eNavigator (an embeddable browser and toolkit)


Networking

Introduction

12.2 VxWorks Network Configuration

Routing Protocols


Host Names and Tables

Domain Name Service

Dynamic Host Configuration Protocol


Host Names

• To associate a name with an internet address:

hostAdd (hostName, hostAddr)

• To display host name table use:

hostShow ( )

• The name of the boot host is automatically added to the

table from the boot parameters.

Example:

-> hostAdd “tuolumne”, “147.11.12.14”value = 0 = 0x0

-> hostAdd “todd”, “147.11.12.14”value = 0 = 0x0

-> hostShowhostname inet address aliases-------- ------------ -----------t12-164 147.11.12.164localhost 127.0.0.1wolverine 147.11.12.165tuolumne 147.11.12.14 toddvalue = 0 = 0x0


Domain Name System

• Domain Name System (DNS) is a distributed

client/server application supporting host names being

stored in a distributed database.

• DNS requires a name server and, on the client side, a

resolver. VxWorks supports resolver functionality in

resolvLib.

• resolvLib includes the following routines:

● resolvGetHostByName() -- send a DNS query to thename server for the IP address of a host.

● resolvGetHostByAddr() -- send a DNS query to thename server for the host name of an IP address.

• The name server must have a corresponding route in the target routing

table.

• hostLib contains two related routines, hostGetByName() and

hostGetByAddr(), which normally use the local host name table.

However, if resolvLib is configured and a host name or IP address is

not found locally, then a DNS query will be sent.

• DNS is described in RFC’s 1034 and 1035.


DNS Resolver Configuration

• The DNS resolver component (/network

components/networking applications/DNS resolver) must be

added to VxWorks.

• The resolver must be initialized before use. Required

information includes RESOLVER_DOMAIN and

RESOLVER_DOMAIN_SERVER. This can be done through

the project facility or by calling resolvInit().

• Example configuration:

● RESOLVER_DOMAIN “wrs.com”

● RESOLVER_DOMAIN_SERVER “147.11.254.1”● DNS_DEBUG FALSE

• Setting the DNS_DEBUG flag will result in diagnostic messages being sent

to the console when DNS queries are made.


DHCP Basics

• Dynamic Host Configuration Protocol (DHCP) allows a

host to acquire an IP address, and possibly boot

parameters, from a remote host.

• A DHCP client can obtain a temporary lease of an IP

address from a DHCP server, which maintains a

database of available addresses and other parameters.

A DHCP relay agent is necessary to support DHCP

operation across subnet boundaries.

DHCPrelayagent

DHCPClient

DHCPServer

• The DHCP server database can contain entries that allow BOOTP client

requests to be handled. (BOOTP is a simpler protocol allowing remote

clients to obtain boot parameters.)

• The VxWorks implementation of DHCP conforms to RFC 1541.

• See the VxWorks Network Programmer’s Guide chapter on Booting over theNetwork for more details on DHCP boot configuration.


DHCP ConfigurationDHCPClient

Add component /network components /networking protocols/ network applications/DHCPv4 runtime client.Default parameters:

DHCP client port number = 68

DHCP server port number = 67

Desired lease length = 3600 seconds

Minimum acceptable lease length = 30 seconds

DHCPServer

Add component /network components /networking protocols/ network applications / DHCPServer.Default parameters:

Port numbers the same as for client

DHCP server port number = 67

Max number of hops for DHCP = 4

• The DHCP relay agent configuration is described in the help page for

dhcpsLib. (Yes, the server help file!)

• A DHCP server requires a database of addresses and boot parameters.

A default database is found in

.../target/config/comps/src/net/usrNetDhcpsCfg.c.

• Details on database entries and a server hook to assign permanent

storage for dynamically added addresses can be found on the help page

for dhcpsLib.


Networking

Introduction


12.3 Routing Protocols


Routing Overview

Static Routing

Dynamic Routing


Routing Overview

• Internet Protocol (IP) routing algorithm:

if (destination on a directly attached network)send data to destination

elseuse routing table to find correct routersend data to router

• The target routing table can be built in two ways:

● Statically, by adding routes to a local routing tableusing mRouteAdd() or routeAdd( ).

● Or dynamically, where hosts exchange routinginformation using a routing protocol.

• VxWorks supports two routing protocols: Routing

Information Protocol (RIP) and Open Shortest Path First

(OSPF).

• mRouteAdd(), strangely enough, is found in routeLib.

• RIPv1 and RIPv2 are both supported by ripLib. Differences between

these versions is discussed later.

• OSPF is an optional product.


Adding Static Routes in VxWorks• To add multiple routes to the same location, use

mRouteAdd (dest, gateway, mask, tos, flags)Can use a destination/gateway internet address in dotnotation. Specify destination subnet mask and IP type-of-service. See routeLib help page for details.

• To add a route to the 90.0.0.0 /24 network through the

router gatehost:

mRouteAdd (“90.0.0.0”, “gatehost”, 0xffffff00, 0, 0)

• Routing table show routines, mRouteShow() or

routeShow() require the component /network

components/networking protocols/network debugging/ Network

show routines.

• To delete a route, use mRouteEntryDelete( ) or mRouteDelete( ).

• routeAdd() and routeShow(), while obsolete, are provided for

backwards compatibility.

• Routing example:

->mRouteAdd (“147.11.12.0”, “90.0.0.254”, 0xffffff00, 0, 0)

value = 0 = 0x0

->mRouteShow

Destination Mask TOS Gateway Flags RefCnt Use Interface Proto

0.0.0.0 0 0 90.0.0.1 101 0 0 nt0 0

127.0.0.1 0 0 127.0.0.1 5 0 0 lo0 0

147.11.12.0 ffffff0 0 90.0.0.254 3 0 0 nt0 1

value = 0 = 0x0


Network Show Routines

• Are used to display network statistics and debugging

information. Configuration information and statistics

can be shown for protocols (IP, ICMP, TCP, etc.) ,

buffering, network interfaces, etc.

• Example (ARP table entries):

->arptabShow

LINK LEVEL ARP TABLE

destination gateway flags Refcnt Use Interface

--------------------------------------------------------------------------

147.11.12.14 08:00:20:7b:06:fb 405 0 45 ei0

147.11.12.165 00:60:97:4f:d5:16 405 0 0 ei0

--------------------------------------------------------------------------value = 75 = 0x4b = ‘K’

• ARP is the Address Resolution Protocol, a protocol to find link layer

addresses (ethernet addresses in this example) given an IP address.

• A flag value of 0x405 is 0x400 (generated by ARP) + 0x4 (host specific

entry) + 0x1 (route is “up”)

• The components for network show routines are:


Dynamic Routing Overview

• Dynamic routing protocols allow hosts (typically

routers) to exchange routing information. Advantages

over statically created routing tables include:

● Faster update as link states change

● Ability to calculate the most efficient route if thereare multiple routes to a destination

● Easier maintenance

• These protocols do not affect the Internet routing

algorithm, but instead impose a routing policy when

constructing the routing table.

• VxWorks supports RIP versions 1 and 2 and OSPF (an

optional component).

• The common UNIX routing daemon routed uses RIP.

• RIP and OSPFs are examples of IGPs (Interior Gateway Protocols)

which allow routers within an organization (in formal networking

lingo, an autonomous system) to exchange routing information.


Routing Internet Protocol

• RIP uses UDP to exchange routing information.

• RIP is a distance vector protocol -- each route includes a

number of hop counts. If multiple paths to a

destination exist, RIP chooses the most efficient route

by minimizing this count.

• RIPv2 updates RIPv1 by including:

● support for classless addressing

● ability to use multicasting and broadcasting

● support for authentication

• use ping( ) for testing routes

• See ripLib in the VxWorks Reference Manual for details.

• RIPv2 can also process RIPv1 messages.

• RIPv1 is described in RFC 1058 and RIPv2 in RFC 1388.

• OSPF is a link state protocol -- such protocols do not require wholesale

exchange of routing tables. Instead, OSPF routers exchange

information about link states. This information is used by each router

to calculate an optimal routing table. Link state information includes a

link weight, which reflects delays and bandwidth restrictions on that

network segment. Advantages of OSPF over RIP:

● Link state metrics lead to better optimized routes than hop counts.

● Routing updates occur more promptly.

● OSPF can accomodate larger and more complex organizationnetworks (RIP is limited to hop counts < 16).

• Networking implements OSPF version 2, as defined in RFC 1583.


Networking

Introduction


Routing Protocols

12.4 Remote Access Services

Remote Access Services Supported by VxWorks

Server Services: rlogin, telnet, FTP, NFS

Client Services: NFS, RSH, FTP


VxWorks Remote Services

• A TFTP (Trivial File Transfer Protocol) client and server are also

supplied. TFTP is a light-weight version of FTP implemented using

UDP. It does not support any authentication. See tftpLib and tftpdLibfor details.

• The Target Server File System (TSFS) allows a target to access a host-

based file system using the target server - WDB agent connection. For

details, see the WindView chapter.

VxWorks

SERVER CLIENT

rlogin FTP

telnet NFS

nfsDrv netDrv

NFS FTP RSH


Remote Login and Telnet

• rlogin and telnet offer an alternative to cross-

development using the Tornado target server.

rlogin(UNIX)

and

telnet(Internetprotocol)

Include /network components/networkingprotocols/network applications/RLOGIN server/TELNET server

The target resident shell is required:

/development tool components/ target shellcomponents/target shell

Additional tools can also be linked:

Target resident symbol table.

Target resident show routines.

Target resident module loader/unloader.

• Target-based tools may be useful for in-the-field debugging and

upgrading when a Tornado target server is unavailable. Inclusion of

these tools increases your image size significantly.

• Security can be installed:

● Add the component /network components/networking protocols/networkapplications/RLOGIN|TELNET password protection

● Modify LOGIN_USER_NAME and LOGIN_PASSWORD parameters .

● Add additional users with loginUserAdd( ).• An example of initializing the user login table:

...loginInit();loginUserAdd(“marco”, “bcRzQdybze”);...

In the above code, loginUserAdd( ) adds a user to the login table. Thesecond argument “bcRzQdybze” is the pasword “poloPonY” encryptedwith the vxencrypt tool.


NFS Server Overview

• Allows remote hosts to access a target’s DOS file

systems using NFS protocol.

• By default no authentication is performed.

• Add the component /network components/networking

protocols/network filesystems/NFS server.

• NFS server configuration supports:

1. Create a mountable DOS file system:

dosFsDevInitOptionsSet (DOS_OPT_EXPORT);

2. Export DOS file system:

nfsExport (name, fsId, rdOnly, notUsed);

3. Mount file system on remote host.

• NFS server provides:

mountLib Implements Mount Protocol as defined in InternetRFC 1094.

nfsdLib Implements Network File System Protocol asdefined in Internet RFC 1094.

• NFS server requires the following tasks:

● tMountd Manages mount requests

● tNfsd Enqueues incoming NFS requests

● tNfsd0-tNfsd3 Process incoming NFS requests (number oftasks configurable)

• To access file systems other than DOS from a remote host, use the

VxWorks FTP server.

• Refer to your host documentation for details on mounting a NFS file

system on the remote system.


VxWorks FTP Server

• The FTP server component is included by configuring/network components/networking protocols/networkfilesystems/FTP server.

• When target is booted, should see tFtpdTask (serverdaemon) running.

• FTP security, which will require a valid user name andpassword from clients, can be included by configuring/network components/networking protocols/networkfilesystems/FTP server security.

• The RLOGIN/TELNET password protection component allowsa single user name and encrypted password.Additional users can be added by callingloginUserAdd() in application initialization code.

Example: VxWorks Server and VxWorks Client

• Can also use FTP to boot one VxWorks target from another.

-> pBlkDev = ramDevCreate(0, 512, 0, 400,0)

-> dosFsMkfs (“/RAM1”,pBlkDev)

-> fd =creat(“/RAM1/dataFile”,2)

-> write(fd,dataPtr,nBytes)

-> close (fd)

-> netDevCreate (“VxServer:”, “VxServer”, 1)

-> fd = open(“VxServer:”“/RAM1/dataFile”, 2)

-> read(fd, dataBuf, maxSize)

-> close (fd)

VxClientVxServer


NFS vs. FTP Server

• NFS Advantages:

● Efficient file access.

● Configurable number of servers pre-spawned.

• FTP Advantages:

● Can access file systems other than DOS.

● All network hosts have FTP client.


NFS Client Service

• Network File System (NFS) was developed by Sun

Microsystems.

• Allows efficient access to files. NFS transfers and

buffers files in pieces (usually 8 Kbytes).

• Remote file systems are mounted, then accessed as if

they were local file systems.

• VxWorks provides NFS client and server.

• The NFS client component can be found under /network

components/networking protocols/network filesystems/NFS client.

• Windows NT, Windows 98, and Windows 95 require additional

software to support NFS. Numerous third-party packages are available.


NFS Client Configuration

To access files on a remote machine using NFS:

0. Export server’s file system:

Makes the local file system available to remote hostwith appropriate access permissions

1. Mount the file system on the client.nfsMount ( host , fileSystem , localName )

2. Set the client’s authentication parameters:nfsAuthUnixSet ( hostName , uid , gid , ngids , aup_gids )

Defaults ( NFS_GROUP_ID = 100 and NFS_USER_ID =2001) will need to be changed. UNIX users can get therequired values using:

% iduid=219(marc) gid=700(training)

Exporting the server’s file system, is host-dependent:

• For UNIX hosts, exported file systems and access permissions are often

specified in /etc/exports. Under Solaris, the appropriate file is

/etc/dfs/dfstab. (UNIX Host)

• For PC hosts, export and access information are stored as specified by

NFS software. Authentication may not be necessary. (PC Host)

To find the remote host a file system is mounted from:

-> nfsDevShowdevice name file system----------- ---------------/usrNfs styx:/usr/dinoNfs columbia:/dinovalue = 0 = 0x0


netDrv File Access Clients

• netDrv allows access to remote files:

● Entire file read into target memory on open( ).● read( )/write( ) act on copy of file in memory.

● File not written to remote host until close( ).

• Can’t access large files (constrained by available

memory).

• ioctl (fd, FIOSYNC, 0) is not supported.

• dirLib routines opendir / readdir do not work on

netDrv directories. stat / fstat are only partially

implemented.

• stat and fstat only work on regular files. The only fields that are filled

in are the file size, file type (always IFREG if netDrv can open it), and

device pointer


Creating network Devices

STATUS netDevCreate (devName, host,protocol)

devName Local name of device to create. Byconvention, ends with ‘:’.

host Name of remote machine (from previoushostAdd( )).

protocol Protocol to transfer files to/fromVxWorks (0=RSH or 1=FTP).

• Example

-> netDevCreate (“ohio:”, “ohio”, 1)

-> fd = open (“ohio:/u/teamN”, 2)

• FTP file access requires a name and a password set via remCurIdSet( )or:

iam (“team8”, “team8Password”);

• RSH access requires your target name in ~/.rhosts.

• When using FTP, the netDrv routines call lower level functions

implemented in the FTP client library, ftpLib.


Executing Remote Commands

• VxWorks programs can invoke remote shell (RSH)

commands on a UNIX host.

• A file descriptor called a socket is created. Can read( )from this socket to get command output.

RSHclient

RSHserver

shell

shellcmd

socket

UNIX

VxWorks

• Commercial RSH servers are available for Windows machines, for

instance from Denicomp Systems. Shareware implementations are also

available on the web.

• Access permission requires a user name to be set on the target via

remCurIdSet( ) or iam().

• For RSH permission, can put target name in either ~/.rhosts, or in

/etc/hosts.equiv. The latter is dangerous, as it allows a VxWorks user to

set a name and access files arbitrarily. The former only allows a

VxWorks user to access files as a single, usually non-root, user.

• rcmd() and rlogin() to UNIX also use the RSH protocol.


UNIX: Remote Command Execution

int rcmd (host, remotePort, localUser,remoteUser, cmd, pFd2)

host Host name or inet number.

remotePort Remote port number to connect to,typically 514 (RSH server).

localUser Name of local user.

remoteUser User name on remote host.

cmd Shell command string to execute.

pFd2 If non-zero, a socket for stderr is foreachi (*.o)returned through this pointer.

• Returns a socket file descriptor or ERROR.

• The remoteUser parameter is used by the RSH server to find a .rhostsfile.

• The RSH server can restrict access by a target to a specific user name,

i.e., the localUser parameter.

• For additional remote command execution routines see remLib in the

Reference Manual.

• Close the socket file descriptor when your task has finished using it.

UNIXshell

RSHclient

stdout

stderr

fd1

fd2

int fd1, fd2;...fd1 = rcmd (..., &fd2);...


netDrv Client Services Comparison

• Advantages of FTP over RSH:

● FTP is part of the TCP/IP protocol suite, so it isavailable on all networked hosts.

● FTP is faster on open/close, since there is no shelldelay.

● FTP server is supplied with VxWorks.

• Advantages of RSH over FTP:

● FTP clear text password goes over the network oneach open( ) and close( ).

• A netDrv device for accessing files on the boot host is automatically

created at boot time.

• Remote shell protocol (RSH) is a UNIX protocol for executing

commands remotely. (UNIX Host)

• File transfer protocol (FTP) is an internet protocol for remote file

transfer.


netDrv vs. nfsDrv

• Advantages of nfsDrv over netDrv:

● Reads and writes only needed parts of the file.

● Can access arbitrarily large files.

● open( )/close( ) much faster.

● Can use dirLib routines.

● Can flush file changes with FIOSYNC.

• Advantages of netDrv over nfsDrv:

● All networked hosts have an FTP server.

● Easier to configure.

● read( )/write( ) slightly faster.


Summary

• Internet Protocol for node-to-node routing.

• MUX layer decouples link-layer driver and network

protocol.

• Configuring the network

● Configure host name table using hostAdd() or useDNS resolver.

● Configure host’s routing table using mrouteAdd() oruse RIP/OSPF.

• Show routines are available to troubleshoot network

configuration.


Summary

• DHCP allows a host to obtain IP address leases and

boot parameters from a remote server.

• DHCP components:

● DHCP Server

● DHCP Relay Agent

● DHCP Client

• rlogin (UNIX Host) and telnet support.

• FTP and NFS servers allows local VxWorks files to be

accessed by a remote machine.


Summary

• nfsDrv mounts remote file systems with nfsMount( )

● Reads and writes portion of remote file.

● File system must be exported by remote host.

• netDrv devices created with netDevCreate( ).

● Entire file is read into VxWorks on open( ), and notupdated until close( ).

● Uses either RSH (UNIX Host) or FTP for file transfer.

● RSH requires name and entry in .rhosts. (UNIX Host)

● FTP requires name and password.

• rcmd ( ) and rlogin() (UNIX Host)

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