PIX/ASA 7.x ou posterior: Exemplo de configuração de VPN IPsec LAN a LAN com redes sobrepostas

Introduction

Este documento descreve as etapas usadas para traduzir (NAT) o tráfego VPN que viaja por um túnel de IPsec de LAN a LAN (L2L) entre dois mecanismos de segurança e também PAT de tráfego da Internet. Cada dispositivo de segurança tem uma rede privada protegida por trás dela. Neste exemplo, dois Cisco Adaptive Security Appliances (ASAs) com redes internas idênticas e sobrepostas são conectadas pelo túnel VPN. Em um cenário normal, a comunicação através da VPN nunca acontece porque os pacotes de ping nunca deixam a sub-rede local desde que o usuário faça ping no endereço IP da mesma sub-rede. Para que essas duas redes internas privadas se comuniquem entre si, o NAT de política é usado em ambos os ASAs para tradução da sub-rede local, de modo que a comunicação ocorra conforme esperado.

Prerequisites

Requirements

Certifique-se de ter configurado o Cisco Adaptive Security Appliance com endereços IP nas interfaces e ter conectividade básica antes de prosseguir com este exemplo de configuração.

Componentes Utilizados

As informações aqui são baseadas nesta versão de software:

• Cisco Adaptive Security Appliance Software versão 7.x e posterior.

The information in this document was created from the devices in a specific lab environment. All of the devices used in this document started with a cleared (default) configuration. If your network is live, make sure that you understand the potential impact of any command.

Produtos Relacionados

Essa configuração também pode ser usada com o Cisco PIX Security Appliance versão 7.x ou posterior.

Conventions

Consulte as Convenções de Dicas Técnicas da Cisco para obter mais informações sobre convenções de documentos.

Configurar

Nesta seção, você encontrará informações para configurar os recursos descritos neste documento.

Nota:Use a Command Lookup Tool (somente clientes registrados) para obter mais informações sobre os comandos usados nesta seção.

Diagrama de Rede

Este documento utiliza a seguinte configuração de rede:

Configurações

Este documento utiliza as seguintes configurações:

• Configuração do ASA-1

• Configuração do ASA-2

ASA-1#show running-config 
: Saved
:
ASA Version 8.0(3)
!
hostname ciscoasa
enable password 8Ry2YjIyt7RRXU24 encrypted
names
!
interface Ethernet0
 nameif outside
 security-level 0
 ip address 172.162.1.1 255.255.255.0

!--- Configure the outside interface.

!

interface Ethernet1
 nameif inside
 security-level 100
 ip address 192.168.1.1 255.255.255.0

!--- Configure the inside interface.


passwd 2KFQnbNIdI.2KYOU encrypted                                                      
ftp mode passive


access-list new extended permit ip 192.168.2.0 255.255.255.0 192.168.3.0 255.255.255.0

!--- This access list (new) is used with the crypto map (outside_map) !--- in order to determine which traffic should be encrypted !--- and sent across the tunnel.



access-list policy-nat extended permit ip 192.168.1.0 255.255.255.0 192.168.3.0 255.255.255.0


!--- The policy-nat ACL is used with the static !--- command in order to match the VPN traffic for translation. 

pager lines 24
mtu outside 1500
mtu inside 1500
no failover
asdm image flash:/asdm-615.bin
no asdm history enable
arp timeout 14400


static (inside,outside) 192.168.2.0  access-list policy-nat

!--- It is a Policy NAT statement. !--- The static command with the access list (policy-nat), !--- which matches the VPN traffic and translates the source (192.168.1.0) to !--- 192.168.2.0 for outbound VPN traffic.


global (outside) 1 interface
nat (inside) 1 0.0.0.0 0.0.0.0 0 0

!--- The previous statements PAT the Internet traffic !--- except for the VPN traffic that uses the IP address 172.17.1.1. 

route outside 0.0.0.0 0.0.0.0 172.162.1.2 1



!--- Output is suppressed.



!--- PHASE 2 CONFIGURATION ---! !--- The encryption types for Phase 2 are defined here.


crypto ipsec transform-set CISCO esp-des esp-md5-hmac

!--- Define the transform set for Phase 2.

crypto map outside_map 20 match address new

!--- Define which traffic should be sent to the IPsec peer with the !--- access list (new). 

crypto map outside_map 20 set peer 172.162.1.2

!--- Sets the IPsec peer (remote end point)


crypto map outside_map 20 set transform-set CISCO

!--- Sets the IPsec transform set "CISCO" !--- to be used with the crypto map entry "outside_map"

crypto map outside_map interface outside

!--- Specifies the interface to be used with !--- the settings defined in this configuration !--- PHASE 1 CONFIGURATION ---! !--- This configuration uses isakmp policy 65535. !--- Policy 65535 is included in the configuration by default. !--- These configuration commands define the !--- Phase 1 policy parameters that are used.

crypto isakmp identity address
crypto isakmp enable outside
crypto isakmp policy 65535
 authentication pre-share
 encryption des
 hash md5
 group 2
 lifetime 86400

tunnel-group 172.162.1.2 type ipsec-l2l

!--- In order to create and manage the database of connection-specific records !--- for IPsec-L2L—IPsec (LAN-to-LAN) tunnels, use the tunnel-group !--- command in global configuration mode. !--- For L2L connections, the name of the tunnel group must be !--- the IP address of the IPsec peer (remote peer end).

tunnel-group 172.162.1.2 ipsec-attributes
 pre-shared-key *

!--- Enter the pre-shared key in order to configure the authentication method. 


telnet timeout 5
ssh timeout 5
console timeout 0
!
class-map inspection_default
 match default-inspection-traffic
!
!
policy-map global_policy
 class inspection_default
  inspect dns maximum-length 512
  inspect ftp
  inspect h323 h225
  inspect h323 ras
  inspect netbios
  inspect rsh
  inspect rtsp
  inspect skinny
  inspect esmtp
  inspect sqlnet
  inspect sunrpc
  inspect tftp
  inspect sip
  inspect xdmcp
!
service-policy global_policy global
Cryptochecksum:33e1e37cd1280d908210dac0cc26e706
: end

ASA-2#show running-config 
: Saved
:
ASA Version 8.0(3)
!
hostname ASA-2
enable password 8Ry2YjIyt7RRXU24 encrypted
names
!
interface Ethernet0
 nameif outside
 security-level 0
 ip address 172.162.1.2 255.255.255.0                                                
!
interface Ethernet1
 nameif inside
 security-level 100
 ip address 192.168.1.1 255.255.255.0
!

!--- Output is suppressed.


access-list new extended permit ip 192.168.3.0 255.255.255.0 192.168.2.0 255.255.255.0

!--- This access list (new) is used with the crypto map (outside_map) !--- in order to determine which traffic needs to be encrypted !--- and sent across the tunnel.



access-list policy-nat extended permit ip 192.168.1.0 255.255.255.0 192.168.2.0 255.255.255.0


!--- The policy-nat ACL is used with the static !--- command in order to match the VPN traffic for translation. 

pager lines 24
mtu outside 1500
mtu inside 1500
no failover
asdm image flash:/asdm-615.bin
no asdm history enable
arp timeout 14400



static (inside,outside) 192.168.3.0  access-list policy-nat

!--- This is a Policy NAT statement. !--- The static command with the access list (policy-nat), !--- which matches the VPN traffic and translates the source (192.168.1.0) to !--- 192.168.3.0 for outbound VPN traffic.

global (outside) 1 interface
nat (inside) 1 0.0.0.0 0.0.0.0 0 0

!--- The previous statements PAT the Internet traffic !--- except the VPN traffic that uses the outside interface IP address. 



 
route outside 0.0.0.0 0.0.0.0 172.162.1.2 1

!--- PHASE 2 CONFIGURATION ---! !--- The encryption types for Phase 2 are defined here.


crypto ipsec transform-set CISCO esp-des esp-md5-hmac

!--- Define the transform set for Phase 2.



crypto map outside_map 20 match address new

!--- Define which traffic needs to be sent to the IPsec peer.


crypto map outside_map 20 set peer 172.162.1.1

!--- Sets the IPsec peer.


crypto map outside_map 20 set transform-set CISCO

!--- Sets the IPsec transform set "CISCO" !--- to be used with the crypto map entry "outside_map".


crypto map outside_map interface outside

 !--- Specifies the interface to be used with !--- the settings defined in this configuration. !--- PHASE 1 CONFIGURATION ---! !--- This configuration uses isakmp policy 65535 !--- which is included in the configuration by default. !--- The configuration commands here define the !--- Phase 1 policy parameters that are used.



crypto isakmp identity address
crypto isakmp enable outside
crypto isakmp policy 65535
 authentication pre-share
 encryption des
 hash md5
 group 2
 lifetime 86400


!--- Output is suppressed.



!--- In order to create and manage the database of connection-specific !--- records for IPsec-L2L—IPsec (LAN-to-LAN) tunnels, use the !--- tunnel-group  command in global configuration mode. !--- For L2L connections, the name of the tunnel group must be !--- the IP address of the IPsec peer.


tunnel-group 172.162.1.1 type ipsec-l2l
tunnel-group 172.162.1.1 ipsec-attributes
 pre-shared-key *

!--- Enter the pre-shared key in order to configure the authentication method. 


prompt hostname context
Cryptochecksum:6b505b4a05c1aee96a71e67c23e71865
: end

Verificar

Use esta seção para confirmar se a sua configuração funciona corretamente.

A Output Interpreter Tool ( somente clientes registrados) (OIT) oferece suporte a determinados comandos show. Use a OIT para visualizar uma análise da saída do comando show:

• show crypto isakmp sa – Mostra todas as associações de segurança (SAs) IKE atuais no correspondente.

• show crypto ipsec sa - Mostra as configurações usadas pelas SAs atuais.

Comandos show do ASA-1

ASA-1#show crypto isakmp sa

   

Active SA: 1
    Rekey SA: 0 (A tunnel will report 1 Active and 1 Rekey SA during rekey)
Total IKE SA: 1

1   IKE Peer: 172.162.1.2
    Type    : L2L             Role    : initiator
    Rekey   : no              State   : MM_ACTIVE

ASA-1#show crypto ipsec sa
interface: outside
    Crypto map tag: outside_map, seq num: 20, local addr: 172.162.1.1

      access-list new permit ip 192.168.2.0 255.255.255.0 192.168.3.0 

255.255.2
5.0
      local ident (addr/mask/prot/port): (192.168.2.0/255.255.255.0/0/0)
      remote ident (addr/mask/prot/port): (192.168.3.0/255.255.255.0/0/0)
      current_peer: 172.162.1.2

      #pkts encaps: 9, #pkts encrypt: 9, #pkts digest: 9
      #pkts decaps: 9, #pkts decrypt: 9, #pkts verify: 9
      #pkts compressed: 0, #pkts decompressed: 0
      #pkts not compressed: 9, #pkts comp failed: 0, #pkts decomp failed: 0
      #pre-frag successes: 0, #pre-frag failures: 0, #fragments created: 0
      #PMTUs sent: 0, #PMTUs rcvd: 0, #decapsulated frgs needing reassembly: 0
      #send errors: 0, #recv errors: 0

      local crypto endpt.: 172.162.1.1, remote crypto endpt.: 172.162.1.2

      path mtu 1500, ipsec overhead 58, media mtu 1500
      current outbound spi: 0BA6CD7E

    inbound esp sas:
      spi: 0xFB4BD01A (4216049690)
         transform: esp-des esp-md5-hmac none
         in use settings ={L2L, Tunnel, }
         slot: 0, conn_id: 8192, crypto-map: outside_map
         sa timing: remaining key lifetime (kB/sec): (3824999/27738)
         IV size: 8 bytes
         replay detection support: Y
    outbound esp sas:
      spi: 0x0BA6CD7E (195480958)
         transform: esp-des esp-md5-hmac none
         in use settings ={L2L, Tunnel, }
         slot: 0, conn_id: 8192, crypto-map: outside_map
         sa timing: remaining key lifetime (kB/sec): (3824999/27738)
         IV size: 8 bytes
         replay detection support: Y

ASA-1#show nat


NAT policies on Interface inside:
  match ip inside 192.168.1.0 255.255.255.0 outside 192.168.3.0 255.255.255.0
    static translation to 192.168.2.0
    translate_hits = 12, untranslate_hits = 5
  match ip inside any outside any
    dynamic translation to pool 1 (172.162.1.1 [Interface PAT])
    translate_hits = 0, untranslate_hits = 0
  match ip inside any inside any
    dynamic translation to pool 1 (No matching global)
    translate_hits = 0, untranslate_hits = 0
  match ip inside any dmz any
    dynamic translation to pool 1 (No matching global)
    translate_hits = 0, untranslate_hits = 0

ASA-1#show xlate

1 in use, 1 most used
Global 192.168.2.0 Local 192.168.1.0

Comandos show do ASA-2

ASA-2#show crypto ipsec sa

interface: outside
    Crypto map tag: outside_map, seq num: 20, local addr: 172.162.1.2

      access-list new permit ip 192.168.3.0 255.255.255.0 192.168.2.0 

255.255.25
5.0
      local ident (addr/mask/prot/port): (192.168.3.0/255.255.255.0/0/0)
      remote ident (addr/mask/prot/port): (192.168.2.0/255.255.255.0/0/0)
      current_peer: 172.162.1.1

      #pkts encaps: 9, #pkts encrypt: 9, #pkts digest: 9
      #pkts decaps: 9, #pkts decrypt: 9, #pkts verify: 9
      #pkts compressed: 0, #pkts decompressed: 0
      #pkts not compressed: 9, #pkts comp failed: 0, #pkts decomp failed: 0
      #pre-frag successes: 0, #pre-frag failures: 0, #fragments created: 0
      #PMTUs sent: 0, #PMTUs rcvd: 0, #decapsulated frgs needing reassembly: 0
      #send errors: 0, #recv errors: 0

      local crypto endpt.: 172.162.1.2, remote crypto endpt.: 172.162.1.1

      path mtu 1500, ipsec overhead 58, media mtu 1500
      current outbound spi: FB4BD01A

    inbound esp sas:
      spi: 0x0BA6CD7E (195480958)
         transform: esp-des esp-md5-hmac none
         in use settings ={L2L, Tunnel, }
         slot: 0, conn_id: 8192, crypto-map: outside_map
         sa timing: remaining key lifetime (kB/sec): (4274999/26902)
         IV size: 8 bytes
         replay detection support: Y
    outbound esp sas:
      spi: 0xFB4BD01A (4216049690)
         transform: esp-des esp-md5-hmac none
         in use settings ={L2L, Tunnel, }
         slot: 0, conn_id: 8192, crypto-map: outside_map
         sa timing: remaining key lifetime (kB/sec): (4274999/26902)
         IV size: 8 bytes
         replay detection support: Y

ASA-2#show crypto isakmp sa

Active SA: 1
    Rekey SA: 0 (A tunnel will report 1 Active and 1 Rekey SA during rekey)
Total IKE SA: 1

1   IKE Peer: 172.162.1.1
    Type    : L2L             Role    : responder
    Rekey   : no              State   : MM_ACTIVE

Troubleshoot

Cancele associações de segurança

Ao solucionar problemas, certifique-se de limpar as SAs existentes após fazer uma alteração. No modo privilegiado do PIX, use estes comandos:

• clear crypto ipsec sa - Exclui as SAs IPsec ativas.

• clear crypto isakmp sa - Exclui as SAs IKE ativas.

Comandos para Troubleshooting

A ferramenta Output Interpreter (exclusiva para clientes registrados) é compatível com alguns comandos de exibição.. Use a OIT para visualizar uma análise da saída do comando show.

Nota:Consulte Informações Importantes sobre Comandos de Depuração antes de usar comandos debug.

• debug crypto isakmp – Exibe as negociações IPSec da Fase 2.

• debug crypto isakmp – Exibe as negociações ISAKMP da Fase 1.

Informações Relacionadas

• Soluções de problemas mais comuns para VPN IPsec de acesso remoto e L2L
• PIX 7.0 e Adaptive Security Appliance Port Redirection(Forwarding) com comandos nat, global, estático, conduit e access-list
• PIX/ASA 7.x e FWSM: Declarações de NAT e PAT
• Ferramentas de segurança do Cisco ASA 5500 Series
• Cisco PIX 500 Series Security Appliances
• Negociação IPsec/Protocolos IKE
• Suporte Técnico e Documentação - Cisco Systems