yalg

yalg or Yet Another Looking Glass.

Home page : http://www.sofaraway.org/projects/yalg/
Author : Fabien Tassin <fta@sofaraway.org>

1. Introduction

yalg is an expandable multiprotocol looking glass supporting multiple vendor hardware. Multiple hosts can be queried at once.

Supported protocols are :

IPv4/unicast
IPv4/multicast
IPv6/unicast

Supported vendors are :

Cisco (using rsh commands)
Unix and Unix like
Juniper (not yet available)

Commands are parsed before beeing sent to equipments. Results are also parsed and colorized.

2. Download

yalg-0.05.tar.gz (24 Aug 2000)

3. Requirements

a box with a remote command tool (remote shell, client part)
a Web server with CGIs enabled.
Perl 5.004 or greater
remote access to at least one router/host

4. Installation

Get and untar the latest yalg distribution.
Edit the header of the file called yalg.pl to fit your needs and to ensure that everything is correct :
- perl location [first line]
- $organization : a short name for your organization
- $contact : name and email of the contact in the form 'name <email@domain.net>'
- $rcmd : the absolute filename of a remote shell command. Usually '/usr/bin/rsh'.
  Note: if you use rsh and get "poll: protocol failure in circuit setup", this means that the reverse connection for the stderr channel is filtred somewhere in your network. If your rsh comes from the "net-kit" package, you can apply this patch (it is against netkit-rsh 0.16.1) and then use the '-s' flag that does not connect stderr.
- $defvendor : the default vendor to use when sending a command. Can only be 'cisco' and 'unix' in this version.
- $defipvers : the default IP version. Can be 'IPv4' or 'IPv6'.
- $defiptype : the default IP type. Can be 'unicast' or 'multicast'.
- $defcmd : the default command. This must be one of the 4th key of the $cmds hash reference.
- $hosts : this is a hash reference that lists all hosts and their parameters. The syntax looks complex (it can be), but it can also be simple depending upon your needs.
  Keys are a single string representing the label (the description). It must be unique.
  Values can be of several types :
  - single string : the hostname. Default values apply for all other parameters.
  - hash reference (pairs enclosed by curly brackets) : secondary keys can be :
    - 'host' : the hostname
    - 'ip' : a list reference (elements enclosed be square brackets). In that case, each element can be a protocol version ('IPv4' or 'IPv6') or another list reference of 2 values, protocol version and protocol type.
    - 'vendor' : another vendor (default is $defvendor)
    - 'rcmd' : another remote command (default is $rcmd)
    - 'user' : remote user ($rcmd -l $user $cmd). Default keep the same user.
    Default values apply (for unspecified fields).
  Here is an example :
```
my $defipvers = 'IPv4';
my $defiptype = 'unicast';
my $hosts = {
	     'New York' => 'host1.domain.net',
	     'London'   => 'lon1',
	     'Rio'      => 'Rio',
	     'Paris'    => { 'host' => 'paris-v6',
			     'ip' => [ 'IPv4', 'IPv6' ],
			   },
 	     'Sydney'   => { 'host' => 'r1.syd.aust.domain.net',
			     'ip' => [ [ 'IPv4', 'multicast' ],
				       [ 'IPv4', 'unicast'   ] ],
			   },
};
```
  This will give :
  
  Label Hostname IPv4 IPv6
  
  unicast multicast unicast multicast
  
  London lon1 Yes No No No
  
  New York host1.domain.net Yes No No No
  
  Paris paris-v6 Yes No Yes No
  
  Rio Rio Yes No No No
  
  Sydney r1.syd.aust.domain.net Yes Yes No No
  
  Notes: as it is stored in a hash table, data ordering is lost. Hostnames are not resolved by yalg but by the command which is launched to talk to the equipement (see $rcmd).
- $cmds : this is a hash reference that lists all commands available for a {vendor/IP version/IP type} triplet and the associated parameters. It is not recommanded to change the default value unless you know what you are doing.
  This is a 5 levels hash reference, respectively 'vendor', 'IP version', 'IP type', 'command' and 'argument'.
  The first 3 fields are described above.
  'command' is a short string describing the action.
  Arguments can be :
  - 'cmd' : the command to send
  - 'arg' : a list reference of all argument types allowed for the given command :
    - 'addr' : an IPv4 or IPv6 address (depending of the 2nd key).
    - 'prefix' : an IPv4 or IPv6 prefix
    - 'regexp' : a regular expression (see below)
    - 'none' : no argument allowed.
  - 'parser' : the parser that will be used to display the result of this command. A value of 'foo' needs a function 'parser_foo()' to exist in the code. Default parser is 'default' which keeps the result unchanged.
  Note: if the value associated to the 4th keys is a string (a SCALAR in Perl), this is equivalent to a 5th 'cmd' value, all other default values applied.
  Refer to the code for an example.
- $ASv6 and $ASv4 : hash refrences of ('AS number' => 'AS description') pairs.
  Note: values can be equal or different as netnum and net6num for a given AS sometimes differ.
Check your changes with 'perl -cw yalg.pl'. This should only returns :
```
$ perl -cw yalg.pl
Content-type: text/html

yalg.pl syntax OK
```
Copy this file into a cgi-bin directory. Make it runnable.
Enjoy.

Label	Hostname	IPv4	IPv6
unicast	multicast	unicast	multicast
London	lon1	Yes	No	No	No
New York	host1.domain.net	Yes	No	No	No
Paris	paris-v6	Yes	No	Yes	No
Rio	Rio	Yes	No	No	No
Sydney	r1.syd.aust.domain.net	Yes	Yes	No	No

5. Usage

On the top right, select the IP version/type you want, check the box "Multiple hosts" if you want to be able to send commands to more than one host, then submit with the "Select" button.

On the top left, select a router (or more if "Multiple hosts" is checked), choose a command, optionnaly add an argument then submit with "Probe".

5.1 Arguments

Argument can be of several types including :

IP Address :

  IPv4:      3.0.0.1
             193.251.128.79

  IPv6:      2001:688::1
             2001:688:0:1234::1
             2001:688::193.251.151.79

Prefix :

  IPv4:      3.0.0.0/8
             193.251.128.0/19

  IPv6:      2001:688::/35
             2001:688:0:1234::1/128

Regular expression : "^re(gexp)? [_^]?\d+[_\$]?$"

regexp 234    any AS path matching 234 (this includes AS234, AS1234, AS2345, AS12345...)
re ^234       any AS path starting with 234 (this includes AS234, AS2345..)
re _234       any AS path containing an AS starting with 234
re _234_      any AS path containing exactly AS234
re ^234_      any AS path starting exactly with AS234
re _234$      any AS path ending with AS234

6. Feedbacks

All comments, patches, ideas or feedbacks of any kinds are welcome.

Feel free to visit and to register to http://www.traceroute.org/.

Note: if you are using yalg or any other looking glass for IPv6, please, contact me.