topic Hello, in Network Security

ASA 5505 not using default route

dapasono — Tue, 12 Mar 2019 08:43:30 GMT

Hello.

I'm trying to configure an ASA 5505 (version 9.2(4)) for basic routing on the 192.168.x.y network.

The connection to my ISP is a Cisco RV110W (giving me the 192.168.1.X network) which is running my network just fine, but now I want to add the 5505 on the inside of it. My intent it to connect the 5505 to the 1.X network and use 3.X for the stuff on the far side of the 5505.

I've tried a large number of things, but my current config (shown below) is basically factory default with a few small modifications (I changed the basic IP addresses for vlan1 and vlan2, added PAT and a default route).

I have a hub connected between the 110 and the 5505 for sniffing. When I try to reach the Internet from a PC on the 3.x network, I see the 5505 perform the ARP request for 1.1 but it never seems to use it, It will make the request, and get the answer, multiple times but it doesn't ever show up in a 'show switch mac-address-table' command, and, of course, traffic never passed through. To test traffic flow I'm trying to ping 4.2.2.2 and browse to google.com from the laptop on the 3.X network.

I'm pretty sure I'm missing something very simply, but I can't figure it out (and I feel rather silly). Any help would be appreciated.

Daniel

: Hardware: ASA5505, 256 MB RAM, CPU Geode 500 MHz
: Written by enable_15 at 20:13:46.169 UTC Mon Jan 2 2017
!
ASA Version 9.2(4)
!
hostname ciscoasa
enable password 8Ry2YjIyt7RRXU24 encrypted
names
!
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
!
interface Vlan1
nameif inside
security-level 100
ip address 192.168.3.1 255.255.255.0
!
interface Vlan2
nameif outside
security-level 0
ip address 192.168.1.31 255.255.255.0
!
ftp mode passive
object network obj_any
subnet 0.0.0.0 0.0.0.0
pager lines 24
logging asdm informational
mtu inside 1500
mtu outside 1500
icmp unreachable rate-limit 1 burst-size 1
no asdm history enable
arp timeout 14400
no arp permit-nonconnected
!
object network obj_any
nat (inside,outside) dynamic interface
!
nat (inside,outside) after-auto source dynamic any interface
route outside 0.0.0.0 0.0.0.0 192.168.1.1 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 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
user-identity default-domain LOCAL
http server enable
http 192.168.3.0 255.255.255.0 inside
no snmp-server location
no snmp-server contact
crypto ipsec security-association pmtu-aging infinite
crypto ca trustpool policy
telnet timeout 5
no 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
!
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
!
service-policy global_policy global
prompt hostname context
no call-home reporting anonymous
Cryptochecksum:0d2fe49621e6d561652b8a38fee6ad83
: end

I think your config is

Philip D'Ath — Mon, 02 Jan 2017 22:17:44 GMT

I think your config is correct.

Can your notebook ping 192.168.3.1? Are you sure your notebook is using 192.168.3.1 as its default gateway?

Does the notebook have a second NIC connected, such as to WiFi?

Can the ASA ping the default

Rahul Govindan — Mon, 02 Jan 2017 23:17:08 GMT

Can the ASA ping the default gateway at 192.168.1.1 from its outside interface? If this itself fails, no point looking at the laptop and 192.168.3.x before this is fixed. I would go hop by hop, first ping the 192.168.1.1 ip address from the ASA, better remove the hub in case that is causing an issue. If that works, see if the ASA is able to ping 4.2.2.2. Packet capture on the ASA is a good tool to look at packets coming in an out of the ASA.

http://www.cisco.com/c/en/us/support/docs/security/asa-5500-x-series-next-generation-firewalls/118097-configure-asa-00.html

Once the ASA is able to ping DG and the 4.2.2.2, then the laptop should be fairly straightforward as your config looks ok on first glace.

Yes, the laptop can

dapasono — Tue, 03 Jan 2017 14:19:16 GMT

Yes, the laptop can successfully ping 3.1 and the 5505 can ping the laptop. And the laptop is using 3.1 as its default gateway. The Wifi interface I have turned off to avoid complications leaving only the 1 NIC active.

Could some kind of licensing issue? I bought the 5505 off Ebay and it has a Base license on it running with a permanent activation key.

No, the ASA can not ping the

dapasono — Tue, 03 Jan 2017 15:45:03 GMT

No, the ASA can not ping the default gateway at 1.1. When I try, Wireshark shows me the ASA's ARP request for 1.1 and 1.1's ARP reply, but then the ASA just asks again and 1.1's MAC address never shows up in either 'show arp' nor 'show switch mac-address-table'. It's acting like the ASA just ignores the ARP reply of the default gateway and thus it can't pass any traffic to it.

But, I can ping the other laptop off of that hub (1.17), so I know that the outside interface (e0/0) of the ASA is working correctly with good cables, etc.

Try adding a "switchport mode

Philip D'Ath — Tue, 03 Jan 2017 19:13:46 GMT

Try adding a "switchport mode access" to the "interface Ethernet0/0" interface. Perhaps it is going into trunk mode.

Good thought, but it didn't

dapasono — Tue, 03 Jan 2017 20:18:26 GMT

Good thought, but it didn't help.

I can ping the laptop I have on the hub between the 5505 and the 110, but it keeps ignoring the ARP reply from the 110. I don't get it.

Perhaps try the ASA in a

Philip D'Ath — Tue, 03 Jan 2017 20:21:26 GMT

Perhaps try the ASA in a different port on the hub. There must be some reason why it is not getting the ARP reply.

Hello,

Matt Dunleavy — Tue, 03 Jan 2017 21:21:42 GMT

Hello,

I am a bit confused as to which interface your using for your internal side?

All I see is below which is your external side? is there config missing?

interface Ethernet0/0
switchport access vlan 2

Run a "debug arp" on the ASA

Rahul Govindan — Tue, 03 Jan 2017 21:41:53 GMT

Run a "debug arp" on the ASA to see what the ASA does. One more thought that I had was with subnet masks. Is the gateway also set to 192.168.1.1/24. I am thinking if the ASA thinks that this a non-connected subnet, it might drop the ARP (default since 9.0.1) . You might need to add the following command to allow the traffic through.

arp permit non-connected

Another question: Is the laptop having 1.17 able to ping the default gateway?

Vlan 2 (e0/0) is the outside

dapasono — Tue, 03 Jan 2017 21:47:34 GMT

Vlan 2 (e0/0) is the outside interface, which I'm having trouble with.

Vlan 1 (e0/1 - e0/7) is the inside interface with the 3.X subnet on it.

The ASA's ports are put into Vlan 1 by default, so the config only lists the changes from the default.

When I do a 'show switch vlan' it lists e0/0 in vlan 2 (outside) and the rest in vlan 1 (inside).

Maybe its getting confused as

Matt Dunleavy — Tue, 03 Jan 2017 22:47:50 GMT

Maybe its getting confused as to which interface to route traffic through, what about creating a new vlan instead of the default and assigning it to 1 port and then seeing how it goes.

The 'arp permit-nonconnected'

dapasono — Tue, 03 Jan 2017 23:00:57 GMT

The 'arp permit-nonconnected' has no effect.

Yes, the 110 has it's network interface configured as 192.168.1.1/24.

The debug arp gave this:

ciscoasa(config)# debug arp
debug arp enabled at level 1
ciscoasa(config)# ping 4.2.2.2
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 4.2.2.2, timeout is 2 seconds:
arp-req: generating request for 192.168.1.1 at interface outside
arp-send: arp request built from 192.168.1.31 0026.99d4.5ec4 for 192.168.1.1 at 363830
arp-send: arp request built from 192.168.1.31 0026.99d4.5ec4 for 192.168.1.1 at 365810
?arp-req: generating request for 192.168.1.1 at interface outside
arp-req: request for 192.168.1.1 still pending
arp-send: arp request built from 192.168.1.31 0026.99d4.5ec4 for 192.168.1.1 at 366810
?arp-req: generating request for 192.168.1.1 at interface outside
arp-req: request for 192.168.1.1 still pending
?arp-req: generating request for 192.168.1.1 at interface outside
arp-req: request for 192.168.1.1 still pending
arp-send: arp request built from 192.168.1.31 0026.99d4.5ec4 for 192.168.1.1 at 370810
?arp-req: generating request for 192.168.1.1 at interface outside
arp-req: request for 192.168.1.1 still pending
?
Success rate is 0 percent (0/5)
ciscoasa(config)# no arp-send: arp request built from 192.168.1.31 0026.99d4.5ec4 for 192.168.1.1 at 375810
debug arp
debug arp disabled.
ciscoasa(config)#

At the same time, Wireshark recorded:

1 0.000000 CiscoInc_d4:5e:c4 Broadcast ARP 60 Who has 192.168.1.1? Tell 192.168.1.31
2 0.001068 CiscoInc_50:29:ff CiscoInc_d4:5e:c4 ARP 56 192.168.1.1 is at b8:62:1f:50:29:ff

4 1.970810 CiscoInc_d4:5e:c4 Broadcast ARP 60 Who has 192.168.1.1? Tell 192.168.1.31
5 1.975441 CiscoInc_50:29:ff CiscoInc_d4:5e:c4 ARP 56 192.168.1.1 is at b8:62:1f:50:29:ff
6 2.970770 CiscoInc_d4:5e:c4 Broadcast ARP 60 Who has 192.168.1.1? Tell 192.168.1.31
7 2.975416 CiscoInc_50:29:ff CiscoInc_d4:5e:c4 ARP 56 192.168.1.1 is at b8:62:1f:50:29:ff
8 6.970658 CiscoInc_d4:5e:c4 Broadcast ARP 60 Who has 192.168.1.1? Tell 192.168.1.31
9 6.974900 CiscoInc_50:29:ff CiscoInc_d4:5e:c4 ARP 56 192.168.1.1 is at b8:62:1f:50:29:ff

So it appears that the ASA is discarding the ARP responses from 1.1. But why?

I just set the default route

dapasono — Tue, 03 Jan 2017 23:51:24 GMT

I just set the default route to be the laptop on the 1.x subnet, and the 5505 went out and got its MAC address just fine. So I used that same IP address on the 110 and again the 5505 would not accept the ARP reply.

Could this problem have something to do with the next hop being a Cisco RV110W? Will and ASA not talk with a lesser piece of Cisco equipment??? (I'm grasping at straws here)

Hi,

Pablo — Wed, 04 Jan 2017 00:45:10 GMT

Hi,

What's the status of the interface when it's connected to the RV110W?

Can you configure an ARP-type capture on the ASA?

ASA# capture ARP ethernet-type arp interface outside

ASA# show capture ARP

If you assign the MAC address statically on the ASA are you able to ping the router?

ASA(config)# arp outside 192.168.1.1 b8:62:1f:50:29:ff

Just as a test, have you tried changing the subnet on the router and the ASA to something different, say 192.168.2.0/24?

__ __

Pablo

It could be that the ASA

Rahul Govindan — Wed, 04 Jan 2017 03:26:59 GMT

It could be that the ASA never received the ARP response. The Wireshark you have is on the hub. Catch arp traffic using arp type packet capture on the outside interface of the ASA.

Is the PC connected to the hub able to ping 192.168.1.1? If yes, try swapping ports between the ASA and the PC.

Thanks everybody for your

dapasono — Thu, 05 Jan 2017 13:20:48 GMT

Thanks everybody for your input.

I did try switching ports, to no avail.

Last night I changed the external interface to use DHCP and that fixed things. It didn't like the static IP address for some reason. It wasn't in the DHCP pool of the 110, so I don't understand why, but it is up and passing traffic now.

Again, thanks to everybody for your help with this.

Daniel