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NAT Issues on ASA 5505

I'm having a NAT issue with a ASA 5505 that I set up.  The inside interface is 172.17.0.0/16 and I have a few devices on the inside.  The outside interface is connecting to our office LAN on 172.16.0.0/16.  

On the 172.17.0.0/16 network I can reach outside fine.  From the 172.16.0.0/16 network when I trying connect in, I receive this error on the firewall:

Asymmetric NAT rules matched for forward and reverse flows; Connection for icmp src outside:172.16.13.179 dst inside:172.17.10.10 (type 8, code 0) denied due to NAT reverse path failure


This is what I have for a NAT:

Result of the command: "sh run nat"

nat (inside) 10 0.0.0.0 0.0.0.0



I know its a NAT issue, I'm just not sure what I need to do or add to allow the traffic inbound.  It would be nice if I had a brief explanation to exactly what is happening also and why the added statement fixes the issue.

Thanks!
0
AllDaySentry
Asked:
AllDaySentry
  • 2
1 Solution
 
giltjrCommented:
It appears that 172.16.13.179 (outside) is trying to ping 172.17.10.10 (inside).

I believe the problem is that 172.16.13.179 should be trying to ping 172.17.10.10's NAT'ed address, not it's real address.

Can you post your whole, "cleaned", ASA config file.
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AllDaySentryAuthor Commented:
Below is the config.  Basically I am trying to access the inside IP's by the real address and not having to set up a NAT for each one.

interface Ethernet0/0
 switchport access vlan 2
!
interface Ethernet0/1
 switchport access vlan 9
!
interface Ethernet0/2
 shutdown
!
interface Ethernet0/3
 shutdown
!
interface Ethernet0/4
 shutdown
!
interface Ethernet0/5
 shutdown
!
interface Ethernet0/6
 shutdown
!
interface Ethernet0/7
 shutdown
!
interface Vlan1
 no nameif
 no security-level
 no ip address
!
interface Vlan2
 nameif outside
 security-level 0
 ip address dhcp setroute
!
interface Vlan9
 nameif inside
 security-level 100
 ip address 172.17.9.2 255.255.255.0
!
ftp mode passive
access-list inside_access_in extended permit ip any any
access-list outside_access_in extended permit ip any any
pager lines 24
logging enable
logging asdm informational
mtu outside 1500
mtu inside 1500
icmp unreachable rate-limit 1 burst-size 1
no asdm history enable
arp timeout 14400
global (outside) 10 interface
nat (inside) 10 0.0.0.0 0.0.0.0
access-group outside_access_in in interface outside
access-group inside_access_in in interface inside
route inside 172.17.0.0 255.255.0.0 172.17.9.1 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
timeout floating-conn 0:00:00
dynamic-access-policy-record DfltAccessPolicy
aaa authentication http console LOCAL
http server enable
http 172.17.0.0 255.255.0.0 inside
no snmp-server location
no snmp-server contact
snmp-server enable traps snmp authentication linkup linkdown coldstart
crypto ipsec security-association lifetime seconds 28800
crypto ipsec security-association lifetime kilobytes 4608000
telnet timeout 5
ssh 172.17.0.0 255.255.0.0 inside
ssh timeout 5
console timeout 0

threat-detection basic-threat
threat-detection statistics access-list
no threat-detection statistics tcp-intercept
webvpn
!
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 ip-options
  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
prompt hostname context
no call-home reporting anonymous
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
Cryptochecksum:3a21a10cf7700ba3ac30bb1b3459990c
: end
no asdm history enable
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giltjrCommented:
If I understand your configuration correctly, and how ASA does NAT, the following lines:

global (outside) 10 interface
nat (inside) 10 0.0.0.0 0.0.0.0

Says to do a NAT.  What it should be trying to do is anything going from the inside interface to the outside interface should be NAT'ed to the IP address on the outside interface.

You should be able to try and ping a 172.16.0.0/16 host from a 172.17.0.0/24 host the 172.16.0.0/16 host should see the source IP address as whatever the outside (VLAN2) interface IP address is.

I used to manage a PIX firewall.  It not ASA exactly and it has been awhile.
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lrmooreCommented:
Add
Nat (inside) 0 172.17.0.0 255.255.0.0

If that doesnt work..
Access-list nonat permit ip 172.17.0.0 255.255.0.0 172.16.0.0 255.255.0.0
Nat (inside) 0 access-list nonat
0

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