Contents

Introduction

Prerequisites

Requirements

Components Used

Background Information

Network Diagram

Configure

Solution 1 - Use of the DefaultL2LGroup

Static ASA Configuration

Dynamic ASA

Solution 2 - Create a User-Defined Tunnel-Group

Static ASA Configuration

Dynamic ASA Configuration

Verify

On the Static ASA

On the Dynamic ASA

Troubleshoot

Introduction

This document describes how to configure a site-to-site Internet Key Exchange Version 2 (IKEv2) VPN tunnel between two Adaptive Security Appliances (ASAs) where one ASA has a dynamic IP address and the other has a static IP address.

Prerequisites

Requirements

There are no specific requirements for this document.

Components Used

The information in this document is based on these software and hardware versions:

- ASA Version 5505

- ASA Version 9.1(5)

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.

Background Information

There are two ways that this configuration can be set up:

- With the DefaultL2LGroup tunnel group

- With a named tunnel group

The biggest configuration difference between the two scenarios is the Internet Security Association and Key Management Protocol (ISAKMP) ID used by the remote ASA. When the DefaultL2LGroup is used on the static ASA, the peer's ISAKMP ID has to be the address. However if a named tunnel group is used, the peer's ISAKMP ID has to be the same the tunnel group name using this command:

crypto isakmp identity key-id <tunnel-group_name>

The advantage of using named tunnel groups on the static ASA is that when the DefaultL2LGroup is used, the configuration on the remote dynamic ASAs, which includes the pre-shared keys, has to be identical and it does not allow for much granularity with the setup of policies.

Network Diagram

Configure

This section describes the configuration on each ASA depending on which solution you decide to use.

Solution 1 - Use of the DefaultL2LGroup

This is the simplest way to configure a LAN-to-LAN (L2L) tunnel betwen two ASAs when one ASA gets its address dynamically. The DefaultL2L Group is a preconfigured tunnel group on the ASA and all connections that do not explicitly match any particular tunnel group fall on this connection. Since the Dynamic ASA does not have a constant predetermined IP address, it means the admin cannot configure the Statis ASA in order to allow the connection on a specific tunnel group. In this situation, the DefaultL2L Group can be used in order to allow the dynamic connections.

Tip: With this method, the downside is that all peers will have the same pre-shared key since only one pre-shared key can be defined per tunnel-group and all of the peers will connect to the same DefaultL2LGroup tunnel-group.

Static ASA Configuration

interface Ethernet0/0

nameif inside

security-level 100

IP address 172.30.2.6 255.255.255.0

!

interface Ethernet0/3

nameif Outside

security-level 0

IP address 207.30.43.15 255.255.255.128

!

boot system disk0:/asa915-k8.bin

crypto ipsec IKEv2 ipsec-proposal Site2Site

protocol esp encryption aes-256

protocol esp integrity sha-1

crypto ipsec IKEv2 ipsec-proposal AES256

protocol esp encryption aes-256

protocol esp integrity sha-1 md5

crypto ipsec IKEv2 ipsec-proposal AES192

protocol esp encryption aes-192

protocol esp integrity sha-1 md5

crypto ipsec IKEv2 ipsec-proposal AES

protocol esp encryption aes

protocol esp integrity sha-1 md5

crypto ipsec IKEv2 ipsec-proposal 3DES

protocol esp encryption 3des

protocol esp integrity sha-1 md5

crypto ipsec IKEv2 ipsec-proposal DES

protocol esp encryption des

protocol esp integrity sha-1 md5

crypto engine large-mod-accel

crypto ipsec security-association pmtu-aging infinite

crypto dynamic-map SYSTEM_DEFAULT_CRYPTO_MAP 10 set IKEv2 ipsec-proposal AES256

AES192 AES 3DES DES

crypto dynamic-map SYSTEM_DEFAULT_CRYPTO_MAP 65535 set ikev1 transform-set

ESP-AES-128-SHA ESP-AES-128-MD5 ESP-AES-192-SHA ESP-AES-192-MD5 ESP-AES-

256-SHA ESP-AES-256-MD5 ESP-3DES-SHA ESP-3DES-MD5 ESP-DES-SHA ESP-DES-MD5

crypto dynamic-map SYSTEM_DEFAULT_CRYPTO_MAP 65535 set IKEv2 ipsec-proposal AES256

AES192 AES 3DES DES

crypto map Outside_map 65535 ipsec-isakmp dynamic SYSTEM_DEFAULT_CRYPTO_MAP

crypto map Outside_map interface Outside

crypto IKEv2 policy 2

encryption aes-256

integrity sha512

group 24

prf sha512

lifetime seconds 86400

crypto IKEv2 policy 3

encryption aes-256

integrity sha group 5 2

prf sha

lifetime seconds 86400

crypto IKEv2 policy 10

encryption aes-192

integrity sha

group 5 2

prf sha

lifetime seconds 86400

crypto IKEv2 policy 20

encryption aes

integrity sha

group 5 2

prf sha

lifetime seconds 86400

crypto IKEv2 policy 30

encryption 3des

integrity sha

group 5 2

prf sha

lifetime seconds 86400

crypto IKEv2 policy 40

encryption des

integrity sha

group 5 2

prf sha

lifetime seconds 86400

crypto IKEv2 enable inside client-services port 443

crypto IKEv2 enable Outside client-services port 443

group-policy Site2Site internal

group-policy Site2Site attributes

vpn-idle-timeout none

vpn-session-timeout none

vpn-filter none

vpn-tunnel-protocol IKEv2

tunnel-group DefaultL2LGroup general-attributes

default-group-policy Site2Site

tunnel-group DefaultL2LGroup ipsec-attributes

IKEv2 remote-authentication pre-shared-key *****

IKEv2 local-authentication pre-shared-key *****

On the Adaptive Security Device Manager (ASDM), you can configure the DefaultL2LGroup as shown here:

Dynamic ASA

interface Ethernet0/0

switchport access vlan 2

!

interface Ethernet0/1

!

interface Ethernet0/2

!

interface Ethernet0/3

!

interface Ethernet0/4

!

interface Ethernet0/5

!

interface Ethernet0/6

!

interface Ethernet0/7

!

interface Vlan1

nameif inside

security-level 100

IP address 172.16.1.1 255.255.255.224

!

interface Vlan2

nameif outside

security-level 0

IP address dhcp setroute

!

ftp mode passive

object network NETWORK_OBJ_172.16.1.0_24

subnet 172.16.1.0 255.255.255.0

object-group network DM_INLINE_NETWORK_1

network-object object 10.0.0.0

network-object object 172.0.0.0

access-list outside_cryptomap extended permit IP 172.16.1.0 255.255.255.0

object-group DM_INLINE_NETWORK_1

nat (inside,outside) source static NETWORK_OBJ_172.16.1.0_24 NETWORK_OBJ_

172.16.1.0_24 destination static DM_INLINE_NETWORK_1 DM_INLINE_NETWORK_1

nat (inside,outside) source dynamic any interface

crypto ipsec IKEv2 ipsec-proposal Site2Site

protocol esp encryption aes-256

protocol esp integrity sha-1

crypto ipsec IKEv2 ipsec-proposal DES

protocol esp encryption des

protocol esp integrity sha-1 md5

crypto ipsec IKEv2 ipsec-proposal 3DES

protocol esp encryption 3des

protocol esp integrity sha-1 md5

crypto ipsec IKEv2 ipsec-proposal AES

protocol esp encryption aes

protocol esp integrity sha-1 md5

crypto ipsec IKEv2 ipsec-proposal AES192

protocol esp encryption aes-192

protocol esp integrity sha-1 md5

crypto ipsec IKEv2 ipsec-proposal AES256

protocol esp encryption aes-256

protocol esp integrity sha-1 md5

crypto ipsec security-association pmtu-aging infinite

crypto map outside_map 1 match address outside_cryptomap

crypto map outside_map 1 set pfs group5

crypto map outside_map 1 set peer 198.51.100.1

crypto map outside_map 1 set ikev1 phase1-mode aggressive group5

crypto map outside_map 1 set IKEv2 ipsec-proposal Site2Site

crypto map outside_map interface outside

crypto IKEv2 policy 2

encryption aes-256

integrity sha512

group 24

prf sha512

lifetime seconds 86400

crypto IKEv2 policy 3

encryption aes-256

integrity sha

group 5 2

prf sha

lifetime seconds 86400

crypto IKEv2 policy 10

encryption aes-192

integrity sha

group 5 2

prf sha

lifetime seconds 86400

crypto IKEv2 policy 20

encryption aes

integrity sha

group 5 2

prf sha

lifetime seconds 86400

crypto IKEv2 policy 30

encryption 3des

integrity sha

group 5 2

prf sha

lifetime seconds 86400

crypto IKEv2 policy 40

encryption des

integrity sha

group 5 2

prf sha

lifetime seconds 86400

crypto IKEv2 enable outside

management-access inside

group-policy GroupPolicy_198.51.100.1 internal

group-policy GroupPolicy_198.51.100.1 attributes

vpn-tunnel-protocol IKEv2

tunnel-group 198.51.100.1 type ipsec-l2l

tunnel-group 198.51.100.1 general-attributes

default-group-policy GroupPolicy_198.51.100.1

tunnel-group 198.51.100.1 ipsec-attributes

ikev1 pre-shared-key *****

IKEv2 remote-authentication pre-shared-key *****

IKEv2 local-authentication pre-shared-key *****

On the ASDM, you can use the standard wizard in order to set up the appropriate connection profile or you can simply add a new connection and follow the standard procedure.

Solution 2 - Create a User-Defined Tunnel-Group

This method requires slighly more configuration, but it allows for more granularity. Each peer can have its own separate policy and pre-shared key. However here it is important to change the ISAKMP ID on the dynamic peer so that it uses a name instead of an IP address. This allows the static ASA to match the incoming ISAKMP initialisation request to the right tunnel group and to use the right policies.

Static ASA Configuration

interface Ethernet0/0

nameif inside

security-level 100

IP address 172.16.0.1 255.255.255.0

!

interface Ethernet0/3

nameif Outside

security-level 0

IP address 198.51.100.1 255.255.255.128

!

boot system disk0:/asa915-k8.bin

object-group network DM_INLINE_NETWORK_1

network-object object 10.0.0.0

network-object object 172.0.0.0

access-list Outside_cryptomap_1 extended permit IP object-group DM_INLINE_NETWORK_

1 172.16.1.0 255.255.255.0

crypto ipsec IKEv2 ipsec-proposal Site2Site

protocol esp encryption aes-256

protocol esp integrity sha-1

crypto ipsec IKEv2 ipsec-proposal AES256

protocol esp encryption aes-256

protocol esp integrity sha-1 md5

crypto ipsec IKEv2 ipsec-proposal AES192

protocol esp encryption aes-192

protocol esp integrity sha-1 md5

crypto ipsec IKEv2 ipsec-proposal AES

protocol esp encryption aes

protocol esp integrity sha-1 md5

crypto ipsec IKEv2 ipsec-proposal 3DES

protocol esp encryption 3des

protocol esp integrity sha-1 md5

crypto ipsec IKEv2 ipsec-proposal DES

protocol esp encryption des

protocol esp integrity sha-1 md5

crypto engine large-mod-accel

crypto ipsec security-association pmtu-aging infinite

crypto dynamic-map SYSTEM_DEFAULT_CRYPTO_MAP 65535 set ikev1 transform-set

ESP-AES-128-SHA ESP-AES-128-MD5 ESP-AES-192-SHA ESP-AES-192-MD5 ESP-AES-256-

SHA ESP-AES-256-MD5 ESP-3DES-SHA ESP-3DES-MD5 ESP-DES-SHA ESP-DES-MD5

crypto dynamic-map SYSTEM_DEFAULT_CRYPTO_MAP 65535 set IKEv2 ipsec-proposal

AES256 AES192 AES 3DES DES

crypto dynamic-map DynamicSite2Site1 4 match address Outside_cryptomap_1

crypto dynamic-map DynamicSite2Site1 4 set IKEv2 ipsec-proposal Site2Site

crypto map Outside_map 65534 ipsec-isakmp dynamic DynamicSite2Site1

crypto map Outside_map 65535 ipsec-isakmp dynamic SYSTEM_DEFAULT_CRYPTO_MAP

crypto map Outside_map interface Outside

crypto IKEv2 policy 2

encryption aes-256

integrity sha512

group 24

prf sha512

lifetime seconds 86400

crypto IKEv2 policy 3

encryption aes-256

integrity sha

group 5 2

prf sha

lifetime seconds 86400

crypto IKEv2 policy 10

encryption aes-192

integrity sha

group 5 2

prf sha

lifetime seconds 86400

crypto IKEv2 policy 20

encryption aes

integrity sha

group 5 2

prf sha

lifetime seconds 86400

crypto IKEv2 policy 30

encryption 3des

integrity sha

group 5 2

prf sha

lifetime seconds 86400

crypto IKEv2 policy 40

encryption des

integrity sha

group 5 2

prf sha

lifetime seconds 86400

crypto IKEv2 enable Outside client-services port 443

management-access inside

group-policy GroupPolicy4 internal

group-policy GroupPolicy4 attributes

vpn-tunnel-protocol IKEv2

tunnel-group DynamicSite2Site1 type ipsec-l2l

tunnel-group DynamicSite2Site1 general-attributes

default-group-policy GroupPolicy4

tunnel-group DynamicSite2Site1 ipsec-attributes

IKEv2 remote-authentication pre-shared-key *****

IKEv2 local-authentication pre-shared-key *****

On the ASDM, the connection profile name is an IP address by default. So when you create it, you must change it in order to give it a name as shown in the screenshot here:

Dynamic ASA Configuration

The Dynamic ASA is configured almost the same way in both solutions with the addition of one command as shown here:

crypto isakmp identity key-id DynamicSite2Site1

As described previously, by default the ASA uses the IP address of the interface that the VPN tunnel is mapped to as the ISAKMP key-ID. However in this case, the key-ID on the dynamic ASA is the same as the name of the tunnel-group on the Static ASA. So on every dynamic peer, the key-id will be different and a corresponding tunnel-group must be created on the Static ASA with the right name.

On the ASDM, this can be configured as shown in this screenshot:

Verify

Use this section in order to confirm that your configuration works properly.

On the Static ASA

Here is the result of the show crypto IKEv2 sa det command:

IKEv2 SAs:

Session-id:132, Status:UP-ACTIVE, IKE count:1, CHILD count:1

Tunnel-id                 Local                Remote     Status         Role

1574208993     198.51.100.1/4500    203.0.113.134/4500      READY    RESPONDER

Encr: AES-CBC, keysize: 256, Hash: SHA512, DH Grp:24, Auth sign: PSK,

Auth verify: PSK

Life/Active Time: 86400/352 sec

Session-id: 132

Status Description: Negotiation done

Local spi: 4FDFF215BDEC73EC       Remote spi: 2414BEA1E10E3F70

Local id: 198.51.100.1

Remote id: DynamicSite2Site1

Local req mess id: 13             Remote req mess id: 17

Local next mess id: 13            Remote next mess id: 17

Local req queued: 13              Remote req queued: 17

Local window: 1                   Remote window: 1

DPD configured for 10 seconds, retry 2

NAT-T is detected  outside

Child sa: local selector  172.0.0.0/0 - 172.255.255.255/65535

remote selector 172.16.1.0/0 - 172.16.1.255/65535

ESP spi in/out: 0x9fd5c736/0x6c5b3cc9

AH spi in/out: 0x0/0x0

CPI in/out: 0x0/0x0

Encr: AES-CBC, keysize: 256, esp_hmac: SHA96

ah_hmac: None, comp: IPCOMP_NONE, mode tunnel

Here is the result of the show crypto ipsec sa command:

interface: Outside

Crypto map tag: DynamicSite2Site1, seq num: 4, local addr: 198.51.100.1

access-list Outside_cryptomap_1 extended permit IP 172.0.0.0 255.0.0.0

172.16.1.0 255.255.255.0

local ident (addr/mask/prot/port): (172.0.0.0/255.0.0.0/0/0)

remote ident (addr/mask/prot/port): (172.16.1.0/255.255.255.0/0/0)

current_peer: 203.0.113.134

#pkts encaps: 1, #pkts encrypt: 1, #pkts digest: 1

#pkts decaps: 12, #pkts decrypt: 12, #pkts verify: 12

#pkts compressed: 0, #pkts decompressed: 0

#pkts not compressed: 1, #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

#TFC rcvd: 0, #TFC sent: 0

#Valid ICMP Errors rcvd: 0, #Invalid ICMP Errors rcvd: 0

#send errors: 0, #recv errors: 0

local crypto endpt.: 198.51.100.1/4500, remote crypto endpt.:

203.0.113.134/4500

path mtu 1500, ipsec overhead 82(52), media mtu 1500

PMTU time remaining (sec): 0, DF policy: copy-df

ICMP error validation: disabled, TFC packets: disabled

current outbound spi: 6C5B3CC9

current inbound spi : 9FD5C736

inbound esp sas:

spi: 0x9FD5C736 (2681587510)

transform: esp-aes-256 esp-sha-hmac no compression

in use settings ={L2L, Tunnel,  NAT-T-Encaps, IKEv2, }

slot: 0, conn_id: 1081344, crypto-map: DynamicSite2Site1

sa timing: remaining key lifetime (kB/sec): (4193279/28441)

IV size: 16 bytes

replay detection support: Y

Anti replay bitmap:

0x00000000 0x00001FFF

outbound esp sas:

spi: 0x6C5B3CC9 (1817918665)

transform: esp-aes-256 esp-sha-hmac no compression

in use settings ={L2L, Tunnel,  NAT-T-Encaps, IKEv2, }

slot: 0, conn_id: 1081344, crypto-map: DynamicSite2Site1

sa timing: remaining key lifetime (kB/sec): (3962879/28441)

IV size: 16 bytes

replay detection support: Y

Anti replay bitmap:

0x00000000 0x00000001

On the Dynamic ASA

Here is the result of the show crypto IKEv2 sa detail command:

IKEv2 SAs:

Session-id:11, Status:UP-ACTIVE, IKE count:1, CHILD count:1

Tunnel-id                 Local                Remote     Status         Role

1132933595   192.168.50.155/4500     198.51.100.1/4500      READY    INITIATOR

Encr: AES-CBC, keysize: 256, Hash: SHA512, DH Grp:24, Auth sign: PSK,

Auth verify: PSK

Life/Active Time: 86400/267 sec

Session-id: 11

Status Description: Negotiation done

Local spi: 2414BEA1E10E3F70       Remote spi: 4FDFF215BDEC73EC

Local id: DynamicSite2Site1

Remote id: 198.51.100.1

Local req mess id: 13             Remote req mess id: 9

Local next mess id: 13            Remote next mess id: 9

Local req queued: 13              Remote req queued: 9

Local window: 1                   Remote window: 1

DPD configured for 10 seconds, retry 2

NAT-T is detected inside

Child sa: local selector  172.16.1.0/0 - 172.16.1.255/65535

remote selector 172.0.0.0/0 - 172.255.255.255/65535

ESP spi in/out: 0x6c5b3cc9/0x9fd5c736

AH spi in/out: 0x0/0x0

CPI in/out: 0x0/0x0

Encr: AES-CBC, keysize: 256, esp_hmac: SHA96

ah_hmac: None, comp: IPCOMP_NONE, mode tunnel

Here is the result of the show crypto ipsec sa command:

interface: outside

Crypto map tag: outside_map, seq num: 1, local addr: 192.168.50.155

access-list outside_cryptomap extended permit IP 172.16.1.0 255.255.255.0

172.0.0.0 255.0.0.0

local ident (addr/mask/prot/port): (172.16.1.0/255.255.255.0/0/0)

remote ident (addr/mask/prot/port): (172.0.0.0/255.0.0.0/0/0)

current_peer: 198.51.100.1

#pkts encaps: 12, #pkts encrypt: 12, #pkts digest: 12

#pkts decaps: 1, #pkts decrypt: 1, #pkts verify: 1

#pkts compressed: 0, #pkts decompressed: 0

#pkts not compressed: 12, #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

#TFC rcvd: 0, #TFC sent: 0

#Valid ICMP Errors rcvd: 0, #Invalid ICMP Errors rcvd: 0

#send errors: 0, #recv errors: 0

local crypto endpt.: 192.168.50.155/4500, remote crypto endpt.:

198.51.100.1/4500

path mtu 1500, ipsec overhead 82(52), media mtu 1500

PMTU time remaining (sec): 0, DF policy: copy-df

ICMP error validation: disabled, TFC packets: disabled

current outbound spi: 9FD5C736

current inbound spi : 6C5B3CC9

inbound esp sas:

spi: 0x6C5B3CC9 (1817918665)

transform: esp-aes-256 esp-sha-hmac no compression

in use settings ={L2L, Tunnel,  NAT-T-Encaps, PFS Group 5, IKEv2, }

slot: 0, conn_id: 77824, crypto-map: outside_map

sa timing: remaining key lifetime (kB/sec): (4008959/28527)

IV size: 16 bytes

replay detection support: Y

Anti replay bitmap:

0x00000000 0x00000003

outbound esp sas:

spi: 0x9FD5C736 (2681587510)

transform: esp-aes-256 esp-sha-hmac no compression

in use settings ={L2L, Tunnel,  NAT-T-Encaps, PFS Group 5, IKEv2, }

slot: 0, conn_id: 77824, crypto-map: outside_map

sa timing: remaining key lifetime (kB/sec): (4147199/28527)

IV size: 16 bytes

replay detection support: Y

Anti replay bitmap:

0x00000000 0x00000001

The Output Interpreter Tool (registered customers only) supports certain show commands. Use the Output Interpreter Tool in order to view an analysis of show command output.

Troubleshoot

This section provides information you can use in order to troubleshoot your configuration.

The Output Interpreter Tool (registered customers only) supports certain show commands. Use the Output Interpreter Tool in order to view an analysis of show command output.

Note: Refer to Important Information on Debug Commands before you use debug commands.

- deb crypto IKEv2 packet

- deb crypto IKEv2 internal