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Cisco ASA 5505 - Inside to Inside help

Posted on 2009-04-01
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Last Modified: 2012-05-06
Greetings all!

I have a 5505 on 192.168.0.0/24.  I need to access other switches and routers at our remote offices on networks 192.168.1.0/24 and 192.168.20.0/24.  When I try this from my machine, I get:

"Inbound TCP connection denied from 192.168.0.88/63093 to 192.168.1.254/80 flags SYN  on interface inside"

Either this won't work because of the inherit ASA routing security or I need some NAT entries (or something else).  Any advice would be appreciated!   Thank you.

Results of "sh run":


ASA Version 8.0(4)23 
!
hostname ciscoasa
domain-name priority.local
names
!
interface Vlan1
 nameif inside
 security-level 100
 ip address 192.168.0.250 255.255.255.0 
!
interface Vlan2
 nameif outside
 security-level 0
 ip address 174.11.212.132 255.255.255.248 
!
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
!
boot system disk0:/currentsoftware/asa804-23-k8.bin
ftp mode passive
clock timezone EST -5
clock summer-time EDT recurring
dns server-group DefaultDNS
 domain-name priority.local
pager lines 24
logging enable
logging timestamp
logging trap critical
logging asdm informational
logging host inside 192.168.0.160
logging permit-hostdown
mtu inside 1500
mtu outside 1500
ip verify reverse-path interface outside
icmp unreachable rate-limit 1 burst-size 1
icmp deny any outside
asdm image disk0:/currentsoftware/asdm-61557.bin
no asdm history enable
arp timeout 14400
global (outside) 1 interface
nat (inside) 1 0.0.0.0 0.0.0.0
route outside 0.0.0.0 0.0.0.0 174.10.217.134 1
route inside 192.168.1.0 255.255.255.0 192.168.0.1 1
route inside 192.168.20.0 255.255.255.0 192.168.0.1 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
dynamic-access-policy-record DfltAccessPolicy
aaa authentication ssh console LOCAL 
http server enable
http 192.168.0.0 255.255.255.0 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
crypto ca trustpoint ASDM_TrustPoint0
 enrollment self
 subject-name CN=ciscoasa
 crl configure
telnet timeout 5
ssh 192.168.0.0 255.255.255.0 inside
ssh timeout 5
ssh version 2
console timeout 0
dhcpd auto_config outside
!
 
threat-detection basic-threat
threat-detection scanning-threat shun except ip-address 192.168.0.0 255.255.255.0
threat-detection scanning-threat shun except ip-address 192.168.1.0 255.255.255.0
threat-detection scanning-threat shun except ip-address 192.168.2.0 255.255.255.0
threat-detection scanning-threat shun duration 3600
threat-detection statistics host
no threat-detection statistics access-list
no threat-detection statistics tcp-intercept
ntp server 207.5.137.134 source outside prefer
!
class-map inspection_default
 match default-inspection-traffic
!
!
policy-map type inspect dns preset_dns_map
 parameters
  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 
!
service-policy global_policy global
prompt hostname context 
Cryptochecksum:feefdf9142a2a26d7cf45412858d992f
: end

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Question by:knoxlogic
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4 Comments
 
LVL 43

Expert Comment

by:JFrederick29
ID: 24039921
You need to set the 192.168.0.0/24 hosts default gateway to 192.168.0.1 and then make sure the 192.168.0.1 router has a default route via the ASA.

You can enable same interface traffic but you are still going to have an issue with TCP connections.
0
 

Author Comment

by:knoxlogic
ID: 24042102
I'm not sure I can do this, as 192.168.0.1 is setup as our MPLS router, via our LEC.  We/I don't manage that.  
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LVL 43

Accepted Solution

by:
JFrederick29 earned 500 total points
ID: 24042141
Okay, do you have a layer3 switch on the network?

Here's the problem when you attempt to communicate to the remote network with your current setup.

TCP SYN from 192.168.0.10 to 192.168.1.10 goes to ASA then to MPLS router then to client (okay so far)
TCP SYN ACK from 192.168.1.10 goes to MPLS router then to 192.168.0.10 (bypassing ASA).
TCP ACK from 192.168.0.10 to 192.168.1.10 goes to ASA and the ASA denies the connection since it didn't see the SYN ACK.

If you can't use the MPLS router as the gateway for the 192.168.0.0/24 subnet and you don't have a layer 3 switch on the 192.168.0.0/24 subnet, the only other alternative is to add routes to every PC for the remote networks:

route add 192.168.1.0 mask 255.255.255.0 192.168.0.1 -p
route add 192.168.20.0 mask 255.255.255.0 192.168.0.1 -p
0
 

Author Closing Comment

by:knoxlogic
ID: 31565333
I'll have to get a Layer3 switch to get this working "correctly", but for now, your route statements did the trick.  Thanks!

FYI... for anyone seeing this issue and running these route commands in Windows Vista with UAC turned on, you'll have to make sure you run "cmd" as an administrator (being logged in as one doesn't work).  To do this:

start -> type "cmd" -> ctrl-shift-enter

That will put you in "admin" mode for command line.
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