Disable NAT for VPN site to site

[Houari DALI YOUCEF]

Hi everybody,

I work in a company, and we had to make a site to site VPN.

Everything is working good, except that packets sent from my site are NATed, in other words: the firewall of the other site (site_B) see only the IP address of my firewall (Site_A).

I tried to resolve the problem but no success,I think that the Nating of the VPN's packets is the problem.

Here is my current running config:

ASA Version 8.3(2) 
!
hostname ciscoasa
enable password 9U./y4ITpJEJ8f.V encrypted
passwd 2KFQnbNIdI.2KYOU encrypted
names
!
interface Vlan1
 nameif inside
 security-level 100
 ip address 192.168.67.254 255.255.255.0 
!
interface Vlan2
 nameif outside
 security-level 0
 ip address 41.220.X.Y 255.255.255.252 (External WAN public IP Address)
!
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
!
ftp mode passive
clock timezone CET 1
object network obj_any 
 subnet 0.0.0.0 0.0.0.0
object network 41.220.X1.Y1 
 host 41.220.X1.Y1
object network NETWORK_OBJ_192.168.67.0_24 
 subnet 192.168.67.0 255.255.255.0
object network NETWORK_OBJ_172.19.32.0_19 
 subnet 172.19.32.0 255.255.224.0
object network 194.2.176.18 
 host 194.2.XX.YY (External IP address public of the other site (Site_B))
 description 194.2.XX.YY     
access-list inside_access_in extended permit ip any any log warnings 
access-list inside_access_in extended permit ip object NETWORK_OBJ_172.19.32.0_19 object NETWORK_OBJ_192.168.67.0_24 log debugging 
access-list inside_access_in extended permit ip object 194.2.176.18 any log debugging 
access-list inside_access_in extended permit ip any object NETWORK_OBJ_172.19.32.0_19 log debugging 
access-list outside_1_cryptomap extended permit ip 192.168.67.0 255.255.255.0 172.19.32.0 255.255.224.0 log debugging 
access-list outside_1_cryptomap extended permit ip any object NETWORK_OBJ_172.19.32.0_19 log debugging 
access-list 1111 standard permit 172.19.32.0 255.255.224.0 
access-list 1111 standard permit 192.168.67.0 255.255.255.0 
access-list outside_1_cryptomap_1 extended permit ip 172.19.32.0 255.255.224.0 any log debugging 
access-list outside_1_cryptomap_1 extended permit ip any object NETWORK_OBJ_172.19.32.0_19 log debugging 
access-list outside_1_cryptomap_2 extended permit ip 192.168.67.0 255.255.255.0 172.19.32.0 255.255.224.0 log debugging 
access-list outside_1_cryptomap_2 extended permit ip any object NETWORK_OBJ_172.19.32.0_19 log debugging 
access-list outside_access_in extended permit ip any any log warnings 
access-list outside_access_in extended permit ip object 194.2.XX.YY any log debugging 
access-list outside_access_in extended permit ip any object NETWORK_OBJ_172.19.32.0_19 log debugging 
access-list nonat extended permit ip 192.168.67.0 255.255.255.0 176.19.32.0 255.255.224.0 
access-list nonat extended permit ip 192.168.67.0 255.255.255.0 172.19.32.0 255.255.224.0 
pager lines 24
logging enable
logging monitor informational
logging asdm warnings
mtu inside 1500
mtu outside 1500
icmp unreachable rate-limit 1 burst-size 1
icmp permit any inside
icmp permit any outside
no asdm history enable
arp timeout 14400
nat (inside,outside) source dynamic any interface
nat (inside,outside) source static NETWORK_OBJ_192.168.67.0_24 NETWORK_OBJ_192.168.67.0_24 destination static NETWORK_OBJ_172.19.32.0_19 NETWORK_OBJ_172.19.32.0_19
access-group inside_access_in in interface inside
access-group outside_access_in in interface outside
route outside 0.0.0.0 0.0.0.0 41.220.X.Y 1
timeout xlate 3:00:00
timeout conn 1:00:00 half-closed 0:10:00 udp 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
dynamic-access-policy-record DfltAccessPolicy
aaa authentication ssh console LOCAL 
aaa authentication telnet console LOCAL 
http server enable
http 192.168.67.0 255.255.255.0 inside
http 0.0.0.0 0.0.0.0 outside
no snmp-server location
no snmp-server contact
snmp-server enable traps snmp authentication linkup linkdown coldstart
crypto ipsec transform-set ESP-DES-MD5 esp-des esp-md5-hmac 
crypto ipsec transform-set ESP-DES-SHA esp-des esp-sha-hmac 
crypto ipsec security-association lifetime seconds 28800
crypto ipsec security-association lifetime kilobytes 4608000
crypto dynamic-map SYSTEM_DEFAULT_CRYPTO_MAP 65535 set transform-set ESP-DES-MD5
crypto map outside_map 1 match address outside_1_cryptomap_2
crypto map outside_map 1 set peer 194.2.XX.YY 
crypto map outside_map 1 set transform-set ESP-DES-MD5
crypto map outside_map 65535 ipsec-isakmp dynamic SYSTEM_DEFAULT_CRYPTO_MAP
crypto map outside_map interface outside
crypto map inside_map 65535 ipsec-isakmp dynamic SYSTEM_DEFAULT_CRYPTO_MAP
crypto map inside_map interface inside
crypto isakmp enable inside
crypto isakmp enable outside
crypto isakmp policy 10
 authentication pre-share
 encryption des
 hash md5
 group 2
 lifetime 86400
telnet 192.168.67.200 255.255.255.255 inside
telnet timeout 5
ssh 0.0.0.0 0.0.0.0 outside
ssh timeout 30
console timeout 0
dhcpd auto_config outside
!
threat-detection basic-threat
threat-detection statistics access-list
no threat-detection statistics tcp-intercept
webvpn
username bel_md password HSiYQZRzgeT8u.ml encrypted privilege 15
username nebia_said password qQ6OoFJ5IJa6sgLi encrypted privilege 15
tunnel-group 194.2.XX.YY type ipsec-l2l
tunnel-group 194.2.XX.YY ipsec-attributes
 pre-shared-key *****
!
class-map inspection_default
 match default-inspection-traffic
!
!
policy-map type inspect dns preset_dns_map
 parameters
  message-length maximum client auto
  message-length maximum 512
policy-map global_policy
 class inspection_default
  inspect dns preset_dns_map 
  inspect ftp 
  inspect h323 h225 
  inspect h323 ras 
  inspect rsh 
  inspect rtsp 
  inspect esmtp 
  inspect sqlnet 
  inspect skinny  
  inspect sunrpc 
  inspect xdmcp 
  inspect sip  
  inspect netbios 
  inspect tftp 
  inspect ip-options 
  inspect icmp 
  inspect ipsec-pass-thru 
!
service-policy global_policy global
prompt hostname context 
Cryptochecksum:0398876429c949a766f7de4fb3e2037e
: end

If you need another informations or explanation, just ask me.

My Firewall Model: ASA 5505.

Thanks you for help.

[Mohammad Abazeed · Accepted solution]

Hey Houari,

I am suspecting something with the order of your NATing statment which is:

nat (inside,outside) source static NETWORK_OBJ_192.168.67.0_24 NETWORK_OBJ_192.168.67.0_24 destination static NETWORK_OBJ_172.19.32.0_19 NETWORK_OBJ_172.19.32.0_19

Can you please have this change applied on the ASA:

no nat (inside,outside) source static NETWORK_OBJ_192.168.67.0_24 NETWORK_OBJ_192.168.67.0_24 destination static NETWORK_OBJ_172.19.32.0_19 NETWORK_OBJ_172.19.32.0_19

nat (inside,outside) 1 source static NETWORK_OBJ_192.168.67.0_24 NETWORK_OBJ_192.168.67.0_24 destination static NETWORK_OBJ_172.19.32.0_19 NETWORK_OBJ_172.19.32.0_19

Try and let me know how it goes.

If it didn't help, please put the output form a packet-tracer going form your internal network to the remote VPN subnet along with the output from "show nat detail".

HTH,

Mo.

[Houari DALI YOUCEF]

Thank you Mohamad for your response.

I'll do it tomorrow at work (it's 21:20 now)

Thank you.

[Houari DALI YOUCEF]

Hi,

I did the commands on my asa, and the result of the packet tracer:

It seems to be ok ?

I didn't make test with the other site (Site_B), tomorrow i will continue the test with Site_B's IT

Thanks.

[Houari DALI YOUCEF]

Thank you Mohammad Abazeed, that solved my problem.

I just tested with the site_b's IT.

Once more time, thank you

[Mohammad Abazeed]

Good to know .. and you are welcome.