How can I configure my network to allow bi-directional traffic between two lans?

Question

Here's my current setup: (and it may require reworking):

• 2 LAN networks - 192.168.41.0, 192.168.21.0
• 2 Public IP's (they are assigned to us by specifying MAC Addresses - not subnetted) 24.53.x.x, and the other is 192.34.x.x
• Netgear Router
• Linksys Router
• ASA 5505 with base license

I'll try to diagram the network the best I can for now. I'll improve it later when I have better access to tools. I've included my ASA Run config:

• Cable modem -> Switch
• Switch -> Netgear Router and ASA 5505 Netgear
• Router hosts 192.168.41.0 network and is assigned one of the public IPs
• ASA 5505 hosts 192.168.21.0 network and is assigned the other public IP
• I connect switch behind each network (to the router and ASA) - so there are 3 total switches
• In an attempt to join the two networks, I added a Linksys router to the switch behind the 21.0 network and assigned the router an address on the 21.0 network (192.168.21.254).
• I then connected a line into the internet port on the Linksys router and assigned the wan an IP address on the 41.0 network (192.168.41.2).
• On the 41.0 router (Netgear Router) I added a route to the 21.0 network via the 41.2 address
• On the ASA for the 21.0 network, I added a route to the 41.0 network via the 21.254 address. I also added a couple ACL lines to permit traffic as well as same-security-intra-interface.

Previously, I was able to get traffic to flow one way (21.0 can access 41.0 but not the other way around). I'm assuming it has something to do with either a problem in my structure logic or my nat logic. Currently, I can ping the 41.0 network from the 21.0 network but attempts to use other ports (like telnet the smtp server from port 25) fails. I'm hoping, with your support, we can start with what I have here and begin troubleshooting.

ASA CONFIG

: Saved
:
ASA Version 8.2(1)
!
hostname lilprecious
domain-name mydomain.local
enable password 8Ry2YjIyt7RRXU24 encrypted
passwd lVYsshR/yoydoM2/ encrypted
no names
name 192.168.21.10 precious_private
name 192.168.21.1 asa_private
name 192.34.x.56 precious_public
!
interface Vlan1
 nameif inside
 security-level 100
 ip address 192.168.21.1 255.255.255.0
!
interface Vlan2
 nameif outside
 security-level 0
 ip address 192.34.x.56 255.255.252.0
!
interface Ethernet0/0
!
interface Ethernet0/1
!
interface Ethernet0/2
!
interface Ethernet0/3
!
interface Ethernet0/4
!
interface Ethernet0/5
!
interface Ethernet0/6
!
interface Ethernet0/7
 switchport access vlan 2
!
ftp mode passive
dns domain-lookup inside
dns domain-lookup outside
dns server-group DefaultDNS
 domain-name mydomain.local
dns server-group PRECIOUS
 name-server 192.168.21.10
 domain-name mydomain.local
same-security-traffic permit inter-interface
same-security-traffic permit intra-interface
object-group service exchange_server
 service-object icmp
 service-object tcp-udp eq www
 service-object tcp eq 587
 service-object tcp eq https
 service-object tcp eq smtp
object-group service temp
 service-object tcp-udp eq 64092
object-group service temp2
 service-object tcp-udp eq 59867
access-list CASVPN_splitTunnelAcl standard permit 192.168.21.0 255.255.255.0
access-list CASVPN_splitTunnelAcl standard permit 192.168.20.0 255.255.255.0
access-list CASVPN_splitTunnelAcl standard permit 192.168.41.0 255.255.255.0
access-list inside_nat0_outbound extended permit ip 192.168.21.0 255.255.255.0 192.168.20.0 255.255.255.0
access-list inside_nat0_outbound extended permit ip 192.168.20.0 255.255.255.0 192.168.20.0 255.255.255.0
access-list inside_nat0_outbound extended permit ip 192.168.20.0 255.255.255.0 192.168.41.0 255.255.255.0
access-list inside_nat0_outbound extended permit ip 192.168.41.0 255.255.255.0 192.168.21.0 255.255.255.0
access-list inside_nat0_outbound extended permit ip 192.168.21.0 255.255.255.0 192.168.41.0 255.255.255.0
access-list ping extended permit icmp any any echo-reply
access-list ping extended permit tcp any host 192.34.x.56 eq www
access-list ping extended permit object-group exchange_server any host 192.34.x.56
pager lines 24
logging enable
logging asdm informational
mtu inside 1500
mtu outside 1500
ip local pool vpn_clients 192.168.20.100-192.168.20.199 mask 255.255.255.0
icmp unreachable rate-limit 1 burst-size 1
icmp permit any inside
icmp permit any outside
no asdm history enable
arp timeout 14400
global (outside) 1 interface
nat (inside) 0 access-list inside_nat0_outbound
nat (inside) 1 0.0.0.0 0.0.0.0
static (inside,outside) tcp interface smtp 192.168.21.10 smtp netmask 255.255.255.255
static (inside,outside) tcp interface www 192.168.21.10 www netmask 255.255.255.255
static (inside,outside) tcp interface https 192.168.21.10 https netmask 255.255.255.255
static (inside,outside) tcp interface 587 192.168.21.10 587 netmask 255.255.255.255
access-group ping in interface outside
route outside 0.0.0.0 0.0.0.0 192.34.xx.1 1
route inside 192.168.41.0 255.255.255.0 192.168.21.254 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-server Precious protocol ldap
aaa-server Precious (inside) host 192.168.21.10
 timeout 5
 ldap-base-dn DC=mydomain,DC=local
 ldap-scope subtree
 ldap-login-password *
 ldap-login-dn CN=aduser,CN=Users,DC=mydomain,DC=local
 server-type auto-detect
http server enable
http 192.168.21.0 255.255.255.0 inside
http 192.168.20.0 255.255.255.0 inside
no snmp-server location
no snmp-server contact
snmp-server enable traps snmp authentication linkup linkdown coldstart
crypto ipsec transform-set ESP-AES-256-MD5 esp-aes-256 esp-md5-hmac
crypto ipsec transform-set ESP-DES-SHA esp-des esp-sha-hmac
crypto ipsec transform-set ESP-DES-MD5 esp-des esp-md5-hmac
crypto ipsec transform-set ESP-AES-192-MD5 esp-aes-192 esp-md5-hmac
crypto ipsec transform-set ESP-3DES-MD5 esp-3des esp-md5-hmac
crypto ipsec transform-set ESP-AES-256-SHA esp-aes-256 esp-sha-hmac
crypto ipsec transform-set ESP-AES-128-SHA esp-aes esp-sha-hmac
crypto ipsec transform-set ESP-AES-192-SHA esp-aes-192 esp-sha-hmac
crypto ipsec transform-set ESP-AES-128-MD5 esp-aes esp-md5-hmac
crypto ipsec transform-set ESP-3DES-SHA esp-3des 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 pfs group1
crypto dynamic-map SYSTEM_DEFAULT_CRYPTO_MAP 65535 set 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 map outside_map 65535 ipsec-isakmp dynamic SYSTEM_DEFAULT_CRYPTO_MAP
crypto map outside_map interface outside
crypto isakmp enable outside
crypto isakmp policy 5
 authentication pre-share
 encryption 3des
 hash sha
 group 2
 lifetime 86400
crypto isakmp policy 10
 authentication pre-share
 encryption des
 hash sha
 group 2
 lifetime 86400
telnet 192.168.21.0 255.255.255.0 inside
telnet 192.168.20.0 255.255.255.0 inside
telnet timeout 20
ssh timeout 20
console timeout 0
management-access inside
dhcpd auto_config outside
!

threat-detection basic-threat
threat-detection statistics access-list
no threat-detection statistics tcp-intercept
webvpn
group-policy CASVPN internal
group-policy CASVPN attributes
 wins-server value 192.168.21.10
 dns-server value 192.168.21.10
 vpn-tunnel-protocol IPSec
 split-tunnel-policy tunnelspecified
 split-tunnel-network-list value CASVPN_splitTunnelAcl
 default-domain value mydomain.local
tunnel-group CASVPN type remote-access
tunnel-group CASVPN general-attributes
 address-pool vpn_clients
 authentication-server-group Precious
 default-group-policy CASVPN
tunnel-group CASVPN ipsec-attributes
 pre-shared-key *
!
!
prompt hostname context
Cryptochecksum:3b181b87399ae99bb504d3cd42adc880
: end

Solution

You seems to have issues with asymmetric routing and as in example B here: https://supportforums.cisco.com/docs/DOC-14491

Also, adding third interface with basic license may not help you as ASA5505 need separate license for DMZ or third VLAN. This is from Cisco:

Maximum Active VLAN Interfaces for Your License In routed mode, you can configure the following VLANs depending on your license:

• Base license—3 active VLANs. The third VLAN can only be configured to initiate traffic to one other VLAN.
• Security Plus license—20 active VLANs.

In transparent firewall mode, you can configure the following VLANs depending on your license: - Base license—2 active VLANs in 1 bridge group. - Security Plus license—3 active VLANs: 2 active VLANs in 1 bridge group, and 1 active VLAN for the failover link.

Solution:

1. Get manageable network switches that can do static routing and route traffic through them;
2. Get Security Plus license for ASA and connect network 192.168.41.0 to third VLAN, NAT it and all traffic will go though ASA. However, ASA 5505 has 100Mb interfaces and if you need to move large amount of data, solution 1 with manageable switches looks better.

Comments

[joeqwerty]

What do you mean by this statement: "Public IP's (they are assigned to us by specifying MAC Addresses - not subnetted)"?

[Zach]

Sorry. I knew that statement might cause confusion. Essentially, I'm used to bigger ISP's who allocate public IPs to you by creating a subnet with a range of IP addresses. For example, a public IP of 173.167.81.148 with subnet mask of 255.255.255.248 is on a 173.167.81.144 subnet with a default gateway IP and 5 available public IPs. Well this ISP instead reserves an IP address from its public IP pool and requires you tell them the MAC address of the interfaces which will be assigned the static IP address.

[joeqwerty]

Does the Netgear router and the ASA have a public ip address in the same subnet?

[Zach]

No. One is 24.53.x.x, and the other is 192.34.x.x

[Zach]

Interesting idea! I know I can access the 41.x's public ip from 21.x. I'll try that.

[Zach]

That's not an option for me I'm afraid. The tracert crosses networks.

[cpt_fink]

Can the base license on the 5505 have 3 interfaces talking to each other?

[MikeAWood]

I am not a Cisco tech, so not sure.. but this seems to indicate that you can have 3 vlans. (cisco.com/en/US/products/ps6120/prod_models_comparison.html‌​) It looks like maybe they intended the 3rd VLAN to be something like an (un)trusted DMZ, so I am not sure. Might be worth it to give creating another interface a shot and see if it works...

[Zach]

You can with no forward, and I tried to do this last night but it didn't work initially. It states you only need to put no forward to one vlan which I figured I'd forward it VLAN2 which is my internet. I wanted both lans to be able to initiate contact with each other. I'll admit I didn't really dive into the problem but here is another question that does that - serverfault.com/questions/151569/…

[MikeAWood]

I would assume (again, not being a cisco tech) that you wouldn't want no forward in your case if you want both vlans to be accessible from each other. Should be simple routing between the two VLANs. For my Netgear L3 switches, they call this VLAN Routing.

[Zach]

Correct. I was hoping it meant that you sacrifice 1 VLAN forwarding, but that forwarding works to the other, since the limitation on the base license for having a third VLAN requires you apply a "No Forward" to ONE other VLAN. This didn't seem to be the case.

[Zach]

I do have a manageable switch, but I'm considering another way to set things up. I'll get back to this in a couple days.