NAME¶
vpcs - Virtual PC Simulator
SYNOPSIS¶
vpcs [
options] [
scriptfile]
DESCRIPTION¶
VPCS provides a command line interface to nine simulated virtual PCs. You can
ping/trace route from/to them, or ping/trace route other hosts/routers from
the virtual PCs, making it an ideal study tool when you simulate Cisco or
Juniper routers in a Dynamips or GNS3 environment.
Virtual PCs are able to generate and respond to ICMP (ping), TCP and UDP packets
delivered to the application via a UDP pipe or Unix tap interface. If
scriptfile is specified, then vpcs reads the file on start-up and
executes the commands in the scriptfile.
scriptfile must be in
vpcs
script file format.
vpcs listens for messages on nine consecutive UDP ports and sends
messages on nine consecutive UDP ports. By the default,
vpcs listens on
UDP ports 20000 to 20008 and sends messages on UDP ports 30000 to 30008. Each
UDP port pair (20000/30000, 20001/30001...20008/30008) represents a virtual
PC. Virtual PCs are numbered 1 to 9.
OPTIONS¶
- -h, --help
- Print the command line options and exit
- -v
- Print the version information and exit
- -i num
- number of vpc instances to start (default is 9)
- [-r] scriptfile
- If scriptfile is specified, then vpcs reads the file on
start-up and executes the commands in the scriptfile. scriptfile
must be in vpcs script file format. By default, if a file
named startup.vpc exists in the directory where the vpcs
program was started, it will be read and executed when vpcs starts.
The -r option is optional if scriptfile is the last
parameter.
- -p port
- Run vpcs as a daemon process listening on TCP port specified by
port. As a daemon process, vpcs does not present a command
line interface to the user, but the command line interface can be accessed
remotely using a TCP stream application such as telnet or netcat
(nc). Once the daemon has been started, there is no internal
mechanism for terminating the program, and the program must be terminated
by sending a system signal 9, typically by using the command kill -9
PID (where PID is the process id of the vpcs instance)
- -m num
- vpcs uses 9 consecutive MAC addresses for the 9 vpcs stating
at 00:50:79:66:68:00 by default. The -m option adds num to
the last byte of the base MAC address. Should any increment cause the last
byte exceed 0xFF during this process, it will increment to 0x00.
- -e
- On systems that support the /dev/tapx interface (Unix/Linux), run
vpcs in tap mode rather than UDP mode. In tap mode, IP packets are
sent and received via /dev/tapx interfaces rather than via UDP streams.
Typically /dev/tapx interfaces are only available to the root user,
meaning vpcs would also be required to be run by the root user
(sudo vpcs -e) to use tap mode.
- [-u]
- This option is the default and not necessary, but included to contrast
with the -e option. By default, vpcs sends and receives IP
packets to and from specified UDP ports. vpcs listens on UDP port
20000 and sends to port 127.0.0.1:30000 by default. The listening and
sending ports can be manipulated using the -s, -c and
-t options.
UDP Mode Options¶
- -s port
- port specifies the base port number that vpcs uses to listen
for messages. By default vpcs listens for messages on UDP ports
20000 to 20008. By changing the base port that vpcs
listens to using the -s option causes nine consecutive UDP ports to
be used starting at the port specified by port.
- -t ip
- vpcs streams packets to nine UDP ports commencing at
127.0.0.1:30000 by default. The -t option allows you to
stream packets to a remote host as specified by IPv4 address ip.
Typically the remote host will be running dynamips with a cloud connection
configured to link to this host’s IP address.
- -c port
- vpcs streams packets to nine UDP ports commencing at
127.0.0.1:30000. The -c option allows you to stream packets
to a different set of nine ports commencing at the base port number
specified by port.
TAP Mode Options¶
- -d device
- Device name, works only when -i is set to 1
Hypervisor Mode Option¶
- -H port
- Run as a hypervisor, listening on TCP port specified by port. In
the hypervisor mode, you can connect this control port with
telnet, start or stop an instance of vpcs.
EXAMPLES¶
No command line options¶
If you start the
vpcs with no arguments,
vpcs will start and look
for the script
startup.vpc in the current directory. If it exists, it
will run the script. This is the normal way of running the
vpcs. It is
simply envoked from the command line like this:
vpcs
Starting vpcs with an alternative startup file¶
To start
vpcs with a startup script file called say
alternate.vpc,
use the file name as an argument to the
vpcs command:
vpcs alternate.vpc
Running more than nine Virtual PCs¶
Suppose you needed more than nine Virtual PCs, so you want to run a second
instance of
vpcs on your local host. You would have to consider:
1. The VPCs MAC addresses for the second instance would need to be different,
2. The "local" or listening UDP port numbers for the second instance
would have to differ from the first instance.
3. The remote UDP port numbers for the second instance would have to differ from
the first instance.
Since the default local listening port is 20000, and the default remote port is
30000, you would want to start
vpcs with a local listening port of
20009 (or greater) and remote port of 30009 (or greater) . You would also want
the base MAC address to be offset by at least nine to avoid any clashes. In
this case you would use the command:
vpcs -s 20009 -c 30009 -m 9
Running two instances of vpcs that can communicate with each other on the one host¶
Suppose you wanted to run a second instance of
vpcs on your local host
that can communicate with the instance already running with a default
configuration. You would have to consider:
1. The VPCs MAC addresses for the second instance would need to be different,
2. The "local" or listening UDP port numbers for the second instance
would have to match the "remote" port numbers of the first instance
3. The remote UDP port numbers would have to match the "local" or
listening UDP port numbers of the first instance
Since the default local listening port is 20000, and the default remote port is
30000, you would want to start
vpcs with a local listening port of
30000 and remote port of 20000. You would also want the base MAC address to be
offset by at least nine to avoid any clashes. In this case you would use the
command:
vpcs -s 30000 -c 20000 -m 9
BASE INTERFACE¶
vpcs presents the user with a command line interface (unless daemon mode
has been invoked by the
-p option). The interface prompt indicates
which of the 9 virtual PCs currently has focus by indicating the VPC number in
brackets. Eg.:
VPCS[1]
Here the digit 1 inside the brackets indcates that VPC 1 has focus, and any
traffic generated will be sent from VPC 1, and basic
show commands will
relate to VPC 1.
- Basic commands supported are:
- ?
- Print help
- <digit>
- Switch to the VPC<digit>. <digit> range 1 to 9
- arp
- Shortcut for: show arp. Show arp table
- clear [arguments]
- Clear IPv4/IPv6, arp/neighbor cache, command history
- dhcp [-options]
- Shortcut for: ip dhcp. Get IPv4 address via DHCP
- echo <text>
- Display <text> in output
- help
- Print help
- history
- Shortcut for: show history. List the command history
- ip [arguments]
- Configure VPC's IP settings
- load <filename>
- Load the configuration/script from the file <filename>
- ping <host> [-options]
- Ping the network <host> with ICMP (default) or TCP/UDP
- quit
- Quit program
- relay [arguments] <port>
- Relay packets between two UDP port
- rlogin [<ip>] <port>
- Telnet to host relative to HOST PC
- save <filename>
- Save the configuration to the file <filename>
- set [arguments]
- Set VPC name, peer ports, dump options, echo on or off
- show [arguments]
- Print the information of VPCs (default). Try show ?
- sleep <seconds> [text]
- Print <text> and pause the running script for <seconds>
- trace <host> [-options]
- Print the path packets take to network <host>
- version
- Shortcut for: show version
Any text file consisting of valid vpcs commands can be used as a vpcs script
file. Lines in the file beginning with the
# character will be treated
as comments and ignored. Command files can make use of the
echo and
sleep commands to create some form of interactive script.
Script file exececution can be aborted at any time by pressing Ctrl+c. This
means that the
ping <host> -t command (which must be terimated by
Ctrl+c) is not useful in vpcs script files.
HYPERVISOR INTERFACE¶
- commands supported are:
- help | ?
- Print help
- vpcs [parameters]
- Start vpcs daemon with parameters.
- stop id
- Stop vpcs process
- list
- List vpcs process
- disconnect
- Exit the telnet session
- quit [-f]
- Stop vpcs processes and hypervisor, -f force quit without
prompting
- telnet [<ip>] <port>
- Telnet to <port> at <ip> (default 127.0.0.1)
- rlogin [<ip>] <port>
- Same as telnet
BUGS¶
IPv6 implementation is a basic implementation that is not fully implemented.
The
ping <host> -t command (which must be terimated by Ctrl+c) can
not be used in vpcs script files because when Ctrl+c is pressed to stop the
ping, it also aborts the script file execution.
Please send problems, bugs, questions, desirable enhancements, patches etc to
the author.
AUTHOR¶
Paul Meng <mirnshi[AT]gmail.com>
Documentation by Chris Welsh <rednectar.chris[AT]gmail.com>
COPYRIGHT¶
VPCS is free software, distributed under the terms of the "BSD"
licence.
Source code and license can be found at vpcs.sf.net.
For more information, please visit wiki.freecode.com.cn.