Re: Question about NAT

Jordan Taylor · ‎02-15-2018

Current toplogy.

linked,

I was testing some VPN tunnels in my lab and noticed that the tunnels actually work before adding the NO-NAT commands

ie, NAT (inside,outiside) source static Local Local destination static Remote Remote

Is this need for the tunnels to work porperly or was this some kind of Bug that I am seeing? when do you need NO-NAT? from my understanding you always did?

Thanks.

Seb Rupik · ‎02-15-2018

Hi there,

Without the NO-NAT statement, traffic destined to the subnets behind the ASAs would be translated. Are you sure that traffic was not being translated and routed via the vIOS router, ie: not via the VPN.

Once the traffic is translated it will not be matched as 'interesting' traffic by the crypto map. Can you provide the ASA configs?

cheers,

Seb.

Jordan Taylor · ‎02-15-2018

Here you go.

-----------------
ASA(1)
ciscoasa(config)# show run
: Saved

:
: Serial Number: 9A9WVAT421J
: Hardware: ASAv, 2048 MB RAM, CPU Pentium II 3999 MHz, 1 CPU (2 cores)
:
ASA Version 9.5(2)204
!
hostname ciscoasa
enable password 8Ry2YjIyt7RRXU24 encrypted
xlate per-session deny tcp any4 any4
xlate per-session deny tcp any4 any6
xlate per-session deny tcp any6 any4
xlate per-session deny tcp any6 any6
xlate per-session deny udp any4 any4 eq domain
xlate per-session deny udp any4 any6 eq domain
xlate per-session deny udp any6 any4 eq domain
xlate per-session deny udp any6 any6 eq domain
names
!
interface GigabitEthernet0/0
nameif outside
security-level 0
ip address 90.0.0.1 255.255.255.0
!
interface GigabitEthernet0/1
nameif inside
security-level 100
ip address 10.0.0.100 255.255.255.0
!
interface GigabitEthernet0/2
shutdown
no nameif
no security-level
no ip address
!
interface GigabitEthernet0/3
shutdown
no nameif
no security-level
no ip address
!
interface GigabitEthernet0/4
shutdown
no nameif
no security-level
no ip address
!
interface GigabitEthernet0/5
shutdown
no nameif
no security-level
no ip address
!
interface GigabitEthernet0/6
shutdown
no nameif
no security-level
no ip address
!
interface Management0/0
shutdown
no nameif
no security-level
no ip address
!
ftp mode passive
object-group network IN
network-object 10.0.0.0 255.255.255.0
object-group network OUT
network-object 10.0.6.0 255.255.255.0
access-list ACL1 extended permit ip 10.0.0.0 255.255.255.0 10.0.6.0 255.255.255.0
pager lines 23
mtu outside 1500
mtu inside 1500
no failover
no monitor-interface service-module
icmp unreachable rate-limit 1 burst-size 1
no asdm history enable
arp timeout 14400
no arp permit-nonconnected
route outside 0.0.0.0 0.0.0.0 90.0.0.100 1
timeout xlate 3:00:00
timeout pat-xlate 0:00:30
timeout conn 1:00:00 half-closed 0:10:00 udp 0:02:00 sctp 0:02:00 icmp 0:00:02
timeout sunrpc 0:10:00 h323 0:05:00 h225 1:00:00 mgcp 0:05:00 mgcp-pat 0:05:00
timeout sip 0:30:00 sip_media 0:02:00 sip-invite 0:03:00 sip-disconnect 0:02:00
timeout sip-provisional-media 0:02:00 uauth 0:05:00 absolute
timeout tcp-proxy-reassembly 0:01:00
timeout floating-conn 0:00:00
user-identity default-domain LOCAL
no snmp-server location
no snmp-server contact
crypto ipsec ikev2 ipsec-proposal P1
protocol esp encryption aes 3des des
protocol esp integrity sha-1
crypto ipsec security-association pmtu-aging infinite
crypto map cmap 1 match address ACL1
crypto map cmap 1 set peer 110.0.0.2
crypto map cmap 1 set ikev2 ipsec-proposal P1
crypto map cmap interface outside
crypto ca trustpoint _SmartCallHome_ServerCA
no validation-usage
crl configure
crypto ca trustpool policy
auto-import
crypto ca certificate chain _SmartCallHome_ServerCA
certificate ca 6ecc7aa5a7032009b8cebcf4e952d491
308205ec 308204d4 a0030201 0202106e cc7aa5a7 032009b8 cebcf4e9 52d49130
0d06092a 864886f7 0d010105 05003081 ca310b30 09060355 04061302 55533117
30150603 55040a13 0e566572 69536967 6e2c2049 6e632e31 1f301d06 0355040b
13165665 72695369 676e2054 72757374 204e6574 776f726b 313a3038 06035504
0b133128 63292032 30303620 56657269 5369676e 2c20496e 632e202d 20466f72
20617574 686f7269 7a656420 75736520 6f6e6c79 31453043 06035504 03133c56
65726953 69676e20 436c6173 73203320 5075626c 69632050 72696d61 72792043
65727469 66696361 74696f6e 20417574 686f7269 7479202d 20473530 1e170d31
30303230 38303030 3030305a 170d3230 30323037 32333539 35395a30 81b5310b
30090603 55040613 02555331 17301506 0355040a 130e5665 72695369 676e2c20
496e632e 311f301d 06035504 0b131656 65726953 69676e20 54727573 74204e65
74776f72 6b313b30 39060355 040b1332 5465726d 73206f66 20757365 20617420
68747470 733a2f2f 7777772e 76657269 7369676e 2e636f6d 2f727061 20286329
3130312f 302d0603 55040313 26566572 69536967 6e20436c 61737320 33205365
63757265 20536572 76657220 4341202d 20473330 82012230 0d06092a 864886f7
0d010101 05000382 010f0030 82010a02 82010100 b187841f c20c45f5 bcab2597
a7ada23e 9cbaf6c1 39b88bca c2ac56c6 e5bb658e 444f4dce 6fed094a d4af4e10
9c688b2e 957b899b 13cae234 34c1f35b f3497b62 83488174 d188786c 0253f9bc
7f432657 5833833b 330a17b0 d04e9124 ad867d64 12dc744a 34a11d0a ea961d0b
15fca34b 3bce6388 d0f82d0c 948610ca b69a3dca eb379c00 48358629 5078e845
63cd1941 4ff595ec 7b98d4c4 71b350be 28b38fa0 b9539cf5 ca2c23a9 fd1406e8
18b49ae8 3c6e81fd e4cd3536 b351d369 ec12ba56 6e6f9b57 c58b14e7 0ec79ced
4a546ac9 4dc5bf11 b1ae1c67 81cb4455 33997f24 9b3f5345 7f861af3 3cfa6d7f
81f5b84a d3f58537 1cb5a6d0 09e4187b 384efa0f 02030100 01a38201 df308201
db303406 082b0601 05050701 01042830 26302406 082b0601 05050730 01861868
7474703a 2f2f6f63 73702e76 65726973 69676e2e 636f6d30 12060355 1d130101
ff040830 060101ff 02010030 70060355 1d200469 30673065 060b6086 480186f8
45010717 03305630 2806082b 06010505 07020116 1c687474 70733a2f 2f777777
2e766572 69736967 6e2e636f 6d2f6370 73302a06 082b0601 05050702 02301e1a
1c687474 70733a2f 2f777777 2e766572 69736967 6e2e636f 6d2f7270 61303406
03551d1f 042d302b 3029a027 a0258623 68747470 3a2f2f63 726c2e76 65726973
69676e2e 636f6d2f 70636133 2d67352e 63726c30 0e060355 1d0f0101 ff040403
02010630 6d06082b 06010505 07010c04 61305fa1 5da05b30 59305730 55160969
6d616765 2f676966 3021301f 30070605 2b0e0302 1a04148f e5d31a86 ac8d8e6b
c3cf806a d448182c 7b192e30 25162368 7474703a 2f2f6c6f 676f2e76 65726973
69676e2e 636f6d2f 76736c6f 676f2e67 69663028 0603551d 11042130 1fa41d30
1b311930 17060355 04031310 56657269 5369676e 4d504b49 2d322d36 301d0603
551d0e04 1604140d 445c1653 44c1827e 1d20ab25 f40163d8 be79a530 1f060355
1d230418 30168014 7fd365a7 c2ddecbb f03009f3 4339fa02 af333133 300d0609
2a864886 f70d0101 05050003 82010100 0c8324ef ddc30cd9 589cfe36 b6eb8a80
4bd1a3f7 9df3cc53 ef829ea3 a1e697c1 589d756c e01d1b4c fad1c12d 05c0ea6e
b2227055 d9203340 3307c265 83fa8f43 379bea0e 9a6c70ee f69c803b d937f47a
6decd018 7d494aca 99c71928 a2bed877 24f78526 866d8705 404167d1 273aeddc
481d22cd 0b0b8bbc f4b17bfd b499a8e9 762ae11a 2d876e74 d388dd1e 22c6df16
b62b8214 0a945cf2 50ecafce ff62370d ad65d306 4153ed02 14c8b558 28a1ace0
5becb37f 954afb03 c8ad26db e6667812 4ad99f42 fbe198e6 42839b8f 8f6724e8
6119b5dd cdb50b26 058ec36e c4c875b8 46cfe218 065ea9ae a8819a47 16de0c28
6c2527b9 deb78458 c61f381e a4c4cb66
quit
crypto ikev2 policy 1
encryption 3des
integrity sha
group 2
prf sha
lifetime seconds 43200
crypto ikev2 enable outside
telnet timeout 5
ssh stricthostkeycheck
ssh timeout 5
ssh key-exchange group dh-group1-sha1
console timeout 0
threat-detection basic-threat
threat-detection statistics access-list
no threat-detection statistics tcp-intercept
dynamic-access-policy-record DfltAccessPolicy
tunnel-group 90.0.0.2 type ipsec-l2l
tunnel-group 90.0.0.2 ipsec-attributes
ikev2 remote-authentication pre-shared-key *****
ikev2 local-authentication pre-shared-key *****
tunnel-group 110.0.0.2 type ipsec-l2l
tunnel-group 110.0.0.2 ipsec-attributes
ikev2 remote-authentication pre-shared-key *****
ikev2 local-authentication pre-shared-key *****
!
class-map inspection_default
match default-inspection-traffic
!
!
policy-map type inspect dns migrated_dns_map_1
parameters
message-length maximum client auto
message-length maximum 512
policy-map global_policy
class inspection_default
inspect dns migrated_dns_map_1
inspect ftp
inspect h323 h225
inspect h323 ras
inspect ip-options
inspect netbios
inspect rsh
inspect rtsp
inspect skinny
inspect esmtp
inspect sqlnet
inspect sunrpc
inspect tftp
inspect sip
inspect xdmcp
inspect icmp
inspect pptp
!
service-policy global_policy global
prompt hostname context
call-home reporting anonymous prompt 1
call-home
profile CiscoTAC-1
no active
destination address http https://tools.cisco.com/its/service/oddce/services/DDCEService
destination address email callhome@cisco.com
destination transport-method http
subscribe-to-alert-group diagnostic
subscribe-to-alert-group environment
subscribe-to-alert-group inventory periodic monthly
subscribe-to-alert-group configuration periodic monthly
subscribe-to-alert-group telemetry periodic daily
profile License
destination address http https://tools.cisco.com/its/service/oddce/services/DDCEService
destination transport-method http
Cryptochecksum:494fc10f4433c41de8edaa607e9c6adc
: end
---------------------------------
ASA(2)
show run
: Saved

:
: Serial Number: 9AVDT8LR2EB
: Hardware: ASAv, 2048 MB RAM, CPU Pentium II 3999 MHz, 1 CPU (2 cores)
:
ASA Version 9.5(2)204
!
hostname ciscoasa
enable password 8Ry2YjIyt7RRXU24 encrypted
xlate per-session deny tcp any4 any4
xlate per-session deny tcp any4 any6
xlate per-session deny tcp any6 any4
xlate per-session deny tcp any6 any6
xlate per-session deny udp any4 any4 eq domain
xlate per-session deny udp any4 any6 eq domain
xlate per-session deny udp any6 any4 eq domain
xlate per-session deny udp any6 any6 eq domain
names
!
interface GigabitEthernet0/0
nameif outside
security-level 0
ip address 110.0.0.2 255.255.255.0
!
interface GigabitEthernet0/1
shutdown
no nameif
no security-level
no ip address
!
interface GigabitEthernet0/2
shutdown
no nameif
no security-level
no ip address
!
interface GigabitEthernet0/3
nameif inside
security-level 100
ip address 10.0.6.100 255.255.255.0
!
interface GigabitEthernet0/4
shutdown
no nameif
no security-level
no ip address
!
interface GigabitEthernet0/5
shutdown
no nameif
no security-level
no ip address
!
interface GigabitEthernet0/6
shutdown
no nameif
no security-level
no ip address
!
interface Management0/0
shutdown
no nameif
no security-level
no ip address
!
ftp mode passive
object-group network IN
network-object 10.0.6.0 255.255.255.0
object-group network OUT
network-object 10.0.0.0 255.255.255.0
access-list ACL2 extended permit ip 10.0.6.0 255.255.255.0 10.0.0.0 255.255.255.0
pager lines 23
mtu outside 1500
mtu inside 1500
no failover
no monitor-interface service-module
icmp unreachable rate-limit 1 burst-size 1
no asdm history enable
arp timeout 14400
no arp permit-nonconnected
route outside 0.0.0.0 0.0.0.0 110.0.0.110 1
timeout xlate 3:00:00
timeout pat-xlate 0:00:30
timeout conn 1:00:00 half-closed 0:10:00 udp 0:02:00 sctp 0:02:00 icmp 0:00:02
timeout sunrpc 0:10:00 h323 0:05:00 h225 1:00:00 mgcp 0:05:00 mgcp-pat 0:05:00
timeout sip 0:30:00 sip_media 0:02:00 sip-invite 0:03:00 sip-disconnect 0:02:00
timeout sip-provisional-media 0:02:00 uauth 0:05:00 absolute
timeout tcp-proxy-reassembly 0:01:00
timeout floating-conn 0:00:00
user-identity default-domain LOCAL
no snmp-server location
no snmp-server contact
crypto ipsec ikev2 ipsec-proposal P1
protocol esp encryption aes 3des des
protocol esp integrity sha-1
crypto ipsec security-association pmtu-aging infinite
crypto map cmap 1 match address ACL2
crypto map cmap 1 set peer 90.0.0.1
crypto map cmap 1 set ikev2 ipsec-proposal P1
crypto map cmap interface outside
crypto ca trustpoint _SmartCallHome_ServerCA
no validation-usage
crl configure
crypto ca trustpool policy
auto-import
crypto ca certificate chain _SmartCallHome_ServerCA
certificate ca 6ecc7aa5a7032009b8cebcf4e952d491
308205ec 308204d4 a0030201 0202106e cc7aa5a7 032009b8 cebcf4e9 52d49130
0d06092a 864886f7 0d010105 05003081 ca310b30 09060355 04061302 55533117
30150603 55040a13 0e566572 69536967 6e2c2049 6e632e31 1f301d06 0355040b
13165665 72695369 676e2054 72757374 204e6574 776f726b 313a3038 06035504
0b133128 63292032 30303620 56657269 5369676e 2c20496e 632e202d 20466f72
20617574 686f7269 7a656420 75736520 6f6e6c79 31453043 06035504 03133c56
65726953 69676e20 436c6173 73203320 5075626c 69632050 72696d61 72792043
65727469 66696361 74696f6e 20417574 686f7269 7479202d 20473530 1e170d31
30303230 38303030 3030305a 170d3230 30323037 32333539 35395a30 81b5310b
30090603 55040613 02555331 17301506 0355040a 130e5665 72695369 676e2c20
496e632e 311f301d 06035504 0b131656 65726953 69676e20 54727573 74204e65
74776f72 6b313b30 39060355 040b1332 5465726d 73206f66 20757365 20617420
68747470 733a2f2f 7777772e 76657269 7369676e 2e636f6d 2f727061 20286329
3130312f 302d0603 55040313 26566572 69536967 6e20436c 61737320 33205365
63757265 20536572 76657220 4341202d 20473330 82012230 0d06092a 864886f7
0d010101 05000382 010f0030 82010a02 82010100 b187841f c20c45f5 bcab2597
a7ada23e 9cbaf6c1 39b88bca c2ac56c6 e5bb658e 444f4dce 6fed094a d4af4e10
9c688b2e 957b899b 13cae234 34c1f35b f3497b62 83488174 d188786c 0253f9bc
7f432657 5833833b 330a17b0 d04e9124 ad867d64 12dc744a 34a11d0a ea961d0b
15fca34b 3bce6388 d0f82d0c 948610ca b69a3dca eb379c00 48358629 5078e845
63cd1941 4ff595ec 7b98d4c4 71b350be 28b38fa0 b9539cf5 ca2c23a9 fd1406e8
18b49ae8 3c6e81fd e4cd3536 b351d369 ec12ba56 6e6f9b57 c58b14e7 0ec79ced
4a546ac9 4dc5bf11 b1ae1c67 81cb4455 33997f24 9b3f5345 7f861af3 3cfa6d7f
81f5b84a d3f58537 1cb5a6d0 09e4187b 384efa0f 02030100 01a38201 df308201
db303406 082b0601 05050701 01042830 26302406 082b0601 05050730 01861868
7474703a 2f2f6f63 73702e76 65726973 69676e2e 636f6d30 12060355 1d130101
ff040830 060101ff 02010030 70060355 1d200469 30673065 060b6086 480186f8
45010717 03305630 2806082b 06010505 07020116 1c687474 70733a2f 2f777777
2e766572 69736967 6e2e636f 6d2f6370 73302a06 082b0601 05050702 02301e1a
1c687474 70733a2f 2f777777 2e766572 69736967 6e2e636f 6d2f7270 61303406
03551d1f 042d302b 3029a027 a0258623 68747470 3a2f2f63 726c2e76 65726973
69676e2e 636f6d2f 70636133 2d67352e 63726c30 0e060355 1d0f0101 ff040403
02010630 6d06082b 06010505 07010c04 61305fa1 5da05b30 59305730 55160969
6d616765 2f676966 3021301f 30070605 2b0e0302 1a04148f e5d31a86 ac8d8e6b
c3cf806a d448182c 7b192e30 25162368 7474703a 2f2f6c6f 676f2e76 65726973
69676e2e 636f6d2f 76736c6f 676f2e67 69663028 0603551d 11042130 1fa41d30
1b311930 17060355 04031310 56657269 5369676e 4d504b49 2d322d36 301d0603
551d0e04 1604140d 445c1653 44c1827e 1d20ab25 f40163d8 be79a530 1f060355
1d230418 30168014 7fd365a7 c2ddecbb f03009f3 4339fa02 af333133 300d0609
2a864886 f70d0101 05050003 82010100 0c8324ef ddc30cd9 589cfe36 b6eb8a80
4bd1a3f7 9df3cc53 ef829ea3 a1e697c1 589d756c e01d1b4c fad1c12d 05c0ea6e
b2227055 d9203340 3307c265 83fa8f43 379bea0e 9a6c70ee f69c803b d937f47a
6decd018 7d494aca 99c71928 a2bed877 24f78526 866d8705 404167d1 273aeddc
481d22cd 0b0b8bbc f4b17bfd b499a8e9 762ae11a 2d876e74 d388dd1e 22c6df16
b62b8214 0a945cf2 50ecafce ff62370d ad65d306 4153ed02 14c8b558 28a1ace0
5becb37f 954afb03 c8ad26db e6667812 4ad99f42 fbe198e6 42839b8f 8f6724e8
6119b5dd cdb50b26 058ec36e c4c875b8 46cfe218 065ea9ae a8819a47 16de0c28
6c2527b9 deb78458 c61f381e a4c4cb66
quit
crypto ikev2 policy 1
encryption 3des
integrity sha
group 2
prf sha
lifetime seconds 43200
crypto ikev2 enable outside
telnet timeout 5
ssh stricthostkeycheck
ssh timeout 5
ssh key-exchange group dh-group1-sha1
console timeout 0
threat-detection basic-threat
threat-detection statistics access-list
no threat-detection statistics tcp-intercept
dynamic-access-policy-record DfltAccessPolicy
tunnel-group 90.0.0.1 type ipsec-l2l
tunnel-group 90.0.0.1 ipsec-attributes
ikev2 remote-authentication pre-shared-key *****
ikev2 local-authentication pre-shared-key *****
!
class-map inspection_default
match default-inspection-traffic
!
!
policy-map type inspect dns migrated_dns_map_1
parameters
message-length maximum client auto
message-length maximum 512
policy-map global_policy
class inspection_default
inspect dns migrated_dns_map_1
inspect ftp
inspect h323 h225
inspect h323 ras
inspect ip-options
inspect netbios
inspect rsh
inspect rtsp
inspect skinny
inspect esmtp
inspect sqlnet
inspect sunrpc
inspect tftp
inspect sip
inspect xdmcp
inspect icmp
inspect pptp
!
service-policy global_policy global
prompt hostname context
call-home reporting anonymous prompt 1
call-home
profile CiscoTAC-1
no active
destination address http https://tools.cisco.com/its/service/oddce/services/DDCEService
destination address email callhome@cisco.com
destination transport-method http
subscribe-to-alert-group diagnostic
subscribe-to-alert-group environment
subscribe-to-alert-group inventory periodic monthly
subscribe-to-alert-group configuration periodic monthly
subscribe-to-alert-group telemetry periodic daily
profile License
destination address http https://tools.cisco.com/its/service/oddce/services/DDCEService
destination transport-method http
Cryptochecksum:7619e68ffcb84643eed0dd82d5121814
: end

Seb Rupik · ‎02-16-2018

Hi Jordan,

The reason you don't require a NAT exemption rule in your ASAs is because you are not translating any of your inside subnets.

Further to this, both ASAs are clearly able to route to the others inside subnet. For the purpose of your lab this is not a realistic scenario as the vIOS router (the internet") would not know how to route to any internal subnet, especially as you are using RFC1918 class A subnets.

To fix this lab, each ASA should have a default route directed towards the vIOS router. At this stage no other routes are required on either ASA's or the vIOS router. This will necessitate the use of NAT on all of the ASAs and therefore the use of a NAT exemption rule for the establishment of an IPsec tunnel.

cheers,

Seb.

Jordan Taylor · ‎02-16-2018

Okay, I see what is going and correct me if I am wrong in any of this.

If I was translating any of my inside traffic I would need NAT(NO-NAT) for the No translation of the traffi going to my remote site. Since I am not translating any of that traffic it is basically already doing No-NAT.

And at the moment each ASA has a default route to each other. and the tunnels are up. and I am able to send and receive traffic on both ends.

Seb Rupik · ‎02-16-2018

Correct.

Traffic will match ACL1 and ACL2 without the need for NAT exemption.

Just to confirm my suspicions, does the IOS router contain routes for the ASA 'inside' networks, or just the connected subnets?

cheers,

Seb.

Jordan Taylor · ‎02-16-2018

Correct, Only for the connect networks. Thus the tunnels are going all the routing at this poin, for the remote subnets.