Lincoln D. Stein > Net-ISP-Balance-1.04 > Net::ISP::Balance

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Module Version: 1.04   Source   Latest Release: Net-ISP-Balance-1.11

NAME ^

Net::ISP::Balance - Support load balancing across multiple internet service providers

SYNOPSIS ^

 use Net::ISP::Balance;

 # initialize the module with its configuration file
 my $bal = Net::ISP::Balance->new('/etc/network/balance.conf');

 $bal->verbose(1);    # verbosely print routing and firewall 
                      #  commands to STDERR before running them.
 $bal->echo_only(1);  # echo commands to STDOUT; don't execute them.

 # mark the balanced services that are up
 $bal->up('CABLE','DSL','SATELLITE');

 # write out routing and firewall commands
 $bal->set_routes_and_firewall();

 # write out a forwarding rule
 $bal->forward(80 => '192.168.10.35');  # forward web requests to this host

 # write out an arbitrary routing rule
 $bal->ip_route('add 192.168.100.1  dev eth0 src 198.162.1.14');

 # write out an arbitrary iptables rule
 $bal->iptables('-A INCOMING -p tcp --dport 6000 -j REJECT');

 # get information about all services
 my @s = $bal->service_names;
 for my $s (@s) {
    print $bal->dev($s);
    print $bal->ip($s);
    print $bal->gw($s);
    print $bal->net($s);
    print $bal->fwmark($s);
    print $bal->table($s);
    print $bal->running($s);
 }

USAGE ^

This library supports load_balance.pl, a script to load-balance a home network across two or more Internet Service Providers (ISP). The load_balance.pl script can be found in the bin subdirectory of this distribution. Installation and configuration instructions can be found at http://lstein.github.io/Net-ISP-Balance/.

FREQUENTLY-USED METHODS ^

Here are the class methods for this module that can be called on the class name.

$bal = Net::ISP::Balance->new('/path/to/config_file.conf','/path/to/interfaces');

Creates a new balancer object.

The first optional argument is the balancer configuration file, which defaults to /etc/network/balance.conf on Ubuntu/Debian-derived systems, and /etc/sysconfig/network-scripts/balance.conf on RedHat/CentOS-derived systems. From hereon, we'll refer to the base of the various configuration files as $ETC_NETWORK.

The second optional argument is the system network interfaces file, defaulting to $ETC_NETWORK/interfaces.

$bal->set_routes_and_firewall

Once the Balance objecty is created, call set_routes_and_firewall() to configure the routing tables and firewall for load balancing. These rules will either be executed on the system, or printed to standard output as a series of shell script commands if echo_only() is set to true.

The routing tables and firewall rules are based on the configuration described in $ETC_NETWORK/balance.conf. You may add custom routes and rules by creating files in $ETC_NETWORK/balance/routes and $ETC_NETWORK/balance/firewall. The former contains a series of files or perl scripts that define additional routing rules. The latter contains files or perl scripts that define additional firewall rules.

Files located in $ETC_NETWORK/balance/pre-run will be executed just before load_balance.pl emits any route/firewall commands, while those in $ETC_NETWORK/balance/post-run will be run after load_balance.pl is finished.

Any files you put into these directories will be read in alphabetic order and added to the routes and/or firewall rules emitted by the load balancing script.Contained in this directory are subdirectories named "routes" and "firewall". The former contains a series of files or perl scripts that define additional routing rules. The latter contains files or perl scripts that define additional firewall rules.

Note that files ending in ~ or starting with # are treated as autosave files and ignored.

A typical routing rules file will look like the example shown below.

 # file: /etc/network/balance/01.my_routes
 ip route add 192.168.100.1  dev eth0 src 198.162.1.14
 ip route add 192.168.1.0/24 dev eth2 src 10.0.0.4

Each line will be sent to the shell, and it is intended (but not required) that these be calls to the "ip" command. General shell scripting constructs are not allowed here.

A typical firewall rules file will look like the example shown here:

 # file: /etc/network/firewall/01.my_firewall_rules

 # accept incoming telnet connections to the router
 iptable -A INPUT -p tcp --syn --dport telnet -j ACCEPT

 # masquerade connections to the DSL modem's control interface
 iptables -t nat -A POSTROUTING -o eth2 -j MASQUERADE

You may also insert routing and firewall rules via fragments of Perl code, which is convenient because you don't have to hard-code any network addresses and can make use of a variety of shortcuts. To do this, simply end the file's name with .pl and make it executable.

Here's an example that defines a series of port forwarding rules for incoming connections:

 # file: /etc/network/firewall/02.forwardings.pl 

 $B->forward(80 => '192.168.10.35'); # forward port 80 to internal web server
 $B->forward(443=> '192.168.10.35'); # forward port 443 to 
 $B->forward(23 => '192.168.10.35:22'); # forward port 23 to ssh on  web sever

The main thing to know is that on entry to the script the global variable $B will contain an initialized instance of a Net::ISP::Balance object. You may then make method calls on this object to emit firewall and routing rules.

A typical routing rules file will look like the example shown below.

 # file: /etc/network/balance/01.my_routes
 ip route add 192.168.100.1  dev eth0 src 198.162.1.14
 ip route add 192.168.1.0/24 dev eth2 src 10.0.0.4

Each line will be sent to the shell, and it is intended (but not required) that these be calls to the "ip" command. General shell scripting constructs are not allowed here.

A typical firewall rules file will look like the example shown here:

 # file: /etc/network/firewall/01.my_firewall_rules

 # accept incoming telnet connections to the router
 iptable -A INPUT -p tcp --syn --dport telnet -j ACCEPT

 # masquerade connections to the DSL modem's control interface
 iptables -t nat -A POSTROUTING -o eth2 -j MASQUERADE

You may also insert routing and firewall rules via fragments of Perl code, which is convenient because you don't have to hard-code any network addresses and can make use of a variety of shortcuts. To do this, simply end the file's name with .pl and make it executable.

Here's an example that defines a series of port forwarding rules for incoming connections:

 # file: /etc/network/firewall/02.forwardings.pl 

 $B->forward(80 => '192.168.10.35'); # forward port 80 to internal web server
 $B->forward(443=> '192.168.10.35'); # forward port 443 to 
 $B->forward(23 => '192.168.10.35:22'); # forward port 23 to ssh on  web sever

The main thing to know is that on entry to the script the global variable $B will contain an initialized instance of a Net::ISP::Balance object. You may then make method calls on this object to emit firewall and routing rules.

$verbose = $bal->verbose([boolean]);

sub bal_conf_file { my $self = shift; my $d = $self->{bal_conf_file}; $self->{bal_conf_file} = shift if @_; $d; } Get/set verbosity of the module. If verbose is true, then firewall and routing rules will be echoed to STDERR before being executed on the system.

$echo = $bal->echo_only([boolean]);

Get/set the echo_only flag. If this is true (default false), then routing and firewall rules will be printed to STDOUT rathar than being executed.

$result_code = $bal->sh(@args)

Pass @args to the shell for execution. If echo_only() is set to true, the command will not be executed, but instead be printed to standard output.

Example:

 $bal->sh('ip rule flush');

The result code is the same as CORE::system().

$bal->iptables(@args)

Invoke sh() to call "iptables @args".

Example:

 $bal->iptables('-A OUTPUT -o eth0 -j DROP');

You may pass an array reference to iptables(), in which case iptables is called on each member of the array in turn.

Example:

 $bal->iptables(['-P OUTPUT  DROP',
                 '-P INPUT   DROP',
                 '-P FORWARD DROP']);

Note that the method keeps track of rules; if you try to enter the same iptables rule more than once the redundant ones will be ignored.

$bal->firewall_rule($chain,$table,@args)

Issue an iptables firewall rule.

 $chain -- The chain to apply the rule to, e.g. "INPUT". 
 
 $table -- The table to apply the rule to, e.g. "nat". Undef defaults to
           the standard "filter" table.

 @args  -- The other arguments to pass to iptables.

Here is a typical example of blocking incoming connections to port 25:

 $bal->firewall_rule(INPUT=>undef,-p=>'tcp',-dport=>25,-j=>'REJECT');

This will issue the following command:

 iptables -A INPUT -p tcp --dport 25 -j REJECT

The default operation is to append the rule to the chain using -A. This can be changed by passing $bal->firewall_op() any of the strings "append", "delete", "insert" or "check". Subsequent calls to firewall_rule() will return commands for the indicated function:

 $bal->firewall_op('delete');
 $bal->firewall_rule(INPUT=>undef,-p=>'tcp',-dport=>25,-j=>'REJECT');
 # gives  iptables -A INPUT -p tcp --dport 25 -j REJECT

If you want to apply a series of deletes and then revert to the original append behavior, then it is easiest to localize the hash key "firewall_op":

 {
   local $bal->{firewall_op} = 'delete';
   $bal->firewall_rule(INPUT=>undef,-dport=>25,-j=>'ACCEPT');
   $bal->firewall_rule(INPUT->undef,-dport=>80,-j=>'ACCEPT');
 }
 
   $bal->firewall_rule(INPUT=>undef,-dport=>25,-j=>'DROP');
   $bal->firewall_rule(INPUT=>undef,-dport=>80,-j=>'DROP');

$bal->force_route($service_or_device,@selectors)

The force_route() method issues iptables commands that will force certain traffic to travel over a particular ISP service or network device. This is useful, for example, when one of your ISPs acts as your e-mail relay and only accepts connections from the IP address it assigns.

$service_or_device is the symbolic name of an ISP service (e.g. "CABLE") or a network device that a service is attached to (e.g. "eth0").

@selectors are a series of options that will be passed to iptables to select the routing of packets. For example, to forward all outgoing mail (destined to port 25) to the "CABLE" ISP, you would write:

    $bal->force_route('CABLE','--syn','-p'=>'tcp','--dport'=>25);

@selectors is a series of optional arguments that will be passed to iptables on the command line. They will simply be space-separated, and so the following is equivalent to the previous example:

    $bal->force_route('CABLE','--syn -p tcp --dport 25');

Bare arguments that begin with a leading hyphen and are followed by two or more alphanumeric characters are automatically converted into double-hyphen arguments. This allows you to simplify commands slightly. The following is equivalent to the previous examples:

    $bal->force_route('CABLE',-syn,-p=>'tcp',-dport=>25);

You can delete force_route rules by setting firewall_op() to 'delete':

    $bal->firewall_op('delete');
    $bal->force_route('CABLE',-syn,-p=>'tcp',-dport=>25);

$bal->add_route($address => $device, [$masquerade])

This method is used to create routing and firewall rules for a network that isn't mentioned in balance.conf. This may be necessary to route to VPNs and/or to the control interfaces of attached modems.

The first argument is the network address in CIDR format, e.g. '192.168.2.0/24'. The second is the network interface that the network can be accessed via. The third, optional, argument is a boolean. If true, then firewall rules will be set up to masquerade from the LAN into the attached network.

Note that this is pretty limited. If you want to do anything more sophisticated you're better off setting the routes and firewall rules manually.

$table_name = $bal->mark_table($service)

This returns the iptables table name for connections marked for output on a particular ISP service. The name is simply the word "MARK-" appended to the service name. For example, for a service named "DSL", the corresponding firewall table will be named "MARK-DSL".

$bal->forward($incoming_port,$destination_host,@protocols)

This method emits appropriate port/host forwarding rules. Destination host can accept any of these forms:

  192.168.100.1       # forward to same port as incoming
  192.168.100.1:8080  # forward to a different port on host

Protocols are one or more of 'tcp','udp'. If omitted defaults to tcp.

Examples:

    $bal->forward(80 => '192.168.100.1');
    $bal->forward(80 => '192.168.100.1:8080','tcp');

$bal->ip_route(@args)

Shortcut for $bal->sh('ip route',@args);

$bal->ip_rule(@args)

Shortcut for $bal->sh('ip rule',@args);

$verbose = $bal->iptables_verbose([boolean])

Makes iptables send an incredible amount of debugging information to syslog.

QUERYING THE CONFIGURATION ^

These methods allow you to get information about the Net::ISP::Balance object's configuration, including settings and other characteristics of the various network interfaces.

@names = $bal->service_names

Return the list of service names defined in balance.conf.

@names = $bal->isp_services

Return list of service names that correspond to load-balanced ISPs.

@names = $bal->lan_services

Return list of service names that correspond to lans.

$state = $bal->event($service => $new_state)

Record a transition between "up" and "down" for a named service. The first argument is the name of the ISP service that has changed, e.g. "CABLE". The second argument is either "up" or "down".

The method returns a hashref in which the keys are the ISP service names and the values are one of 'up' or 'down'.

The persistent state information is stored in /var/lib/lsm/ under a series of files named <SERVICE_NAME>.state.

@up = $bal->up(@up_services)

Get or set the list of ISP interfaces that are currently active and should be used for balancing.

$services = $bal->services

Return a hash containing the configuration information for each service. The keys are the service names. Here's an example:

 {
 0  HASH(0x91201e8)
   'CABLE' => HASH(0x9170500)
      'dev' => 'eth0'
      'fwmark' => 2
      'gw' => '191.3.88.1'
      'ip' => '191.3.88.152'
      'net' => '191.3.88.128/27'
      'ping' => 'www.google.ca'
      'role' => 'isp'
      'running' => 1
      'table' => 2
   'DSL' => HASH(0x9113e00)
      'dev' => 'ppp0'
      'fwmark' => 1
      'gw' => '112.211.154.198'
      'ip' => '11.120.199.108'
      'net' => '112.211.154.198/32'
      'ping' => 'www.google.ca'
      'role' => 'isp'
      'running' => 1
      'table' => 1
   'LAN' => HASH(0x913ce58)
      'dev' => 'eth1'
      'fwmark' => undef
      'gw' => '192.168.10.1'
      'ip' => '192.168.10.1'
      'net' => '192.168.10.0/24'
      'ping' => ''
      'role' => 'lan'
      'running' => 1
 }

$service = $bal->service('CABLE')

Return the subhash describing the single named service (see services() above).

$dev = $bal->dev('CABLE')

$ip = $bal->ip('CABLE')

$gateway = $bal->gw('CABLE')

$network = $bal->net('CABLE')

$role = $bal->role('CABLE')

$running = $bal->running('CABLE')

$mark_number = $bal->fwmark('CABLE')

$routing_table_number = $bal->table('CABLE')

$ping_dest = $bal->ping('CABLE')

These methods pull out the named information from the configuration data. fwmark() returns a small integer that will be used for marking connections for routing through one of the ISP connections when an outgoing connection originates on the LAN and is routed through the router. table() returns a small integer corresponding to a routing table used to route connections originating on the router itself.

FILES AND PATHS ^

These are methods that determine where Net::ISP::Balance finds its configuration files.

$path = Net::ISP::Balance->install_etc

Returns the path to where the network configuration files reside on this system, e.g. /etc/network. Note that this only knows about Ubuntu/Debian-style network configuration files in /etc/network, and RedHat/CentOS network configuration files in /etc/sysconfig/network-scripts.

$file = Net::ISP::Balance->default_conf_file

Returns the path to the default configuration file, $ETC_NETWORK/balance.conf.

$file_or_dir = Net::ISP::Balance->default_interface_file

Returns the path to the place where the system stores its network configuration information. On Ubuntu/Debian-derived systems, this will be the file /etc/network/interfaces. On RedHad/CentOS-derived systems, this is the directory named /etc/sysconfig/network-scripts/ which contains a series of ifcfg-* files.

$dir = Net::ISP::Balance->default_rules_directory

Returns the path to the directory where the additional router and firewall rules are stored. On Ubuntu-Debian-derived systems, this is /etc/network/balance/. On RedHat/CentOS systems, this is /etc/sysconfig/network-scripts/balance/.

$file = Net::ISP::Balance->default_lsm_conf_file

Returns the path to the place where we should store lsm.conf, the file used to configure the lsm (link status monitor) application.

On Ubuntu/Debian-derived systems, this will be the file /etc/network/lsm.conf. On RedHad/CentOS-derived systems, this will be /etc/sysconfig/network-scripts/lsm.conf.

$dir = Net::ISP::Balance->default_lsm_scripts_dir

Returns the path to the place where lsm stores its helper scripts. On Ubuntu/Debian-derived systems, this will be the directory /etc/network/lsm/. On RedHad/CentOS-derived systems, this will be /etc/sysconfig/network-scripts/lsm/.

$file = $bal->bal_conf_file([$new_file])

Get/set the main configuration file path, balance.conf.

$dir = $bal->rules_directory([$new_rules_directory])

Get/set the route and firewall rules directory.

$file = $bal->lsm_conf_file([$new_conffile])

Get/set the path to the lsm configuration file.

$dir = $bal->lsm_scripts_dir([$new_dir])

Get/set the path to the lsm scripts directory.

INFREQUENTLY-USED METHODS ^

These are methods that are used internally, but may be useful to applications developers.

$lsm_config_text = $bal->lsm_config_file(-warn_email=>'root@localhost')

This method creates the text used to create the lsm.conf configuration file. Pass it a series of -name=>value pairs to incorporate into the file.

Possible switches and their defaults are:

    -checkip                    127.0.0.1
    -eventscript                /etc/network/lsm/balancer_event_script
    -notifyscript               /etc/network/lsm/default_script
    -max_packet_loss            15
    -max_successive_pkts_lost    7
    -min_packet_loss             5
    -min_successive_pkts_rcvd   10
    -interval_ms              1000
    -timeout_ms               1000
    -warn_email               root
    -check_arp                   0
    -sourceip                 <autodiscovered>
    -device                   <autodiscovered>
    -ttl                      0 <use system value>
    -status                   2 <no assumptions>
    -debug                    8 <moderate verbosity from scale of 0 to 100>

$info = $bal->get_ppp_info($dev)

This nmethod returns a hashref containing information about a PPP network interface device, including IP address, gateway, network, and netmask. The $dev argument is a standard Linux network device name such as "ppp0".

$info = $bal->get_static_info($deb)

This nmethod returns a hashref containing information about a statically-defined network interface device, including IP address, gateway, network, and netmask. The $dev argument is a standard Linux network device name such as "etho0".

$info = $bal->get_dhcp_info($deb)

This nmethod returns a hashref containing information about a network interface device that is configured via dhcp, including IP address, gateway, network, and netmask. The $dev argument is a standard Linux network device name such as "eth0".

$path = $bal->find_dhclient_leases($dev)

This method finds the dhclient configuration file corresponding to DHCP-managed device $dev. The device is a standard device name such as "eth0".

$bal->set_routes()

This method is called by set_routes_and_firewall() to emit the rules needed to create the load balancing routing tables.

$bal->set_firewall

This method is called by set_routes_and_firewall() to emit the rules needed to create the balancing firewall.

$bal->enable_forwarding($boolean)

$bal->routing_rules()

This method is called by set_routes() to emit the rules needed to create the routing rules.

$bal->local_routing_rules()

This method is called by set_routes() to process the fules and emit the commands contained in the customized route files located in $ETC_DIR/balance/routes.

$bal->local_fw_rules()

This method is called by set_firewall() to process the fules and emit the commands contained in the customized route files located in $ETC_DIR/balance/firewall.

$bal->pre_run_rules()

This method is called by set_routes_and_firewall() to process the fules and emit the commands contained in the customized route files located in $ETC_DIR/balance/pre-run.

$bal->post_run_rules()

This method is called by set__routes_andfirewall() to process the fules and emit the commands contained in the customized route files located in $ETC_DIR/balance/post-run.

$bal->base_fw_rules()

This method is called by set_firewall() to set up basic firewall rules, including default rules and reporting.

$bal->balancing_fw_rules()

This method is called by set_firewall() to set up the mangle/fwmark rules for balancing outgoing connections.

$bal->sanity_fw_rules()

This is called by set_firewall() to create a sensible series of firewall rules that seeks to prevent spoofing, flooding, and other antisocial behavior. It also enables UDP-based network time and domain name service.

$bal->nat_fw_rules()

This is called by set_firewall() to set up basic NAT rules for lan traffic over ISP

$bal->start_lsm()

Start an lsm process.

$bal->signal_lsm($signal)

Send a signal to a running LSM and return true if successfully signalled. The signal can be numeric (e.g. 9) or a string ('TERM').

BUGS ^

Please report bugs to GitHub: https://github.com/lstein/Net-ISP-Balance.

AUTHOR ^

Copyright 2014, Lincoln D. Stein (lincoln.stein@gmail.com)

Senior Principal Investigator, Ontario Institute for Cancer Research

LICENSE ^

This package is distributed under the terms of the Perl Artistic License 2.0. See http://www.perlfoundation.org/artistic_license_2_0.

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