ASA 5505, EasyVPN, DNS with Split Tunnels

[TechJimF]

Setting up ASA 5505 with split tunnels behind cable modem using DHCP from ISP. Everything works fine when the tunnel is up. But if the tunnel should get disconnected, DNS does not resolve for internet bound traffic.

I know that DNS is being provided by our internal DNS servers and when the tunnel goes down, no more DNS. Can't figure out how to have internal DNS provided by our servers, external DNS (at least if the tunnel is broken) by the ISP.

I can provide a scrubbed config later tonight as the ASA is at home right now.

We are running ASA v8.0.4. Using network extension mode.

Thanks,

Jim

 

[unclerico]

can you post your scrubbed config??

I hate all Uppercase... I don't want my groups to seem angry at me all the time! =)
- ColdFlame (vbscript forum)

 

[TechJimF]

I'll provide it later tonight.

Thanks,

Jim

 

[TechJimF]

This is my scrubbed config:

: Saved
:
ASA Version 8.0(4)
!
hostname XXX-XXX-ASA11
domain-name xxxxxx.com
enable password xxxxxxxxxxxx encrypted
passwd xxxxxxxxxxxxxxxx encrypted
names
!
interface Vlan1
nameif inside
security-level 100
ip address xxx.xxx.xxx.xx 255.255.255.248
!
interface Vlan2
nameif outside
security-level 0
ip address dhcp setroute
!
interface Vlan3
shutdown
no forward interface Vlan1
nameif dmz
security-level 50
no 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
!
boot system disk0:/asa804-k8.bin
ftp mode passive
clock timezone CST -6
clock summer-time CDT recurring
dns domain-lookup inside
dns domain-lookup outside
dns server-group DefaultDNS
name-server 172.xx.x.x2
name-server 172.xx.x.x1
domain-name xxxxxx.com
pager lines 24
logging enable
logging asdm informational
mtu inside 1500
mtu outside 1500
mtu dmz 1500
icmp unreachable rate-limit 1 burst-size 1
asdm image disk0:/asdm-613.bin
no asdm history enable
arp timeout 14400
global (outside) 1 interface
nat (inside) 1 0.0.0.0 0.0.0.0
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
dynamic-access-policy-record DfltAccessPolicy
http server enable
http xx.xxx.xxx.xx 255.255.255.248 inside
http xx.xxx.xxx.xx 255.255.255.248 inside
http xx.xxx.xxx.xx 255.255.255.224 inside
http xx.xxx.xxx.xx 255.255.255.0 inside
http xx.xxx.xxx.xx 255.255.255.0 inside
http xx.xxx.xxx.xx 255.255.0.0 inside
http xx.xxx.xxx.xx 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-3DES-SHA esp-3des esp-sha-hmac
crypto ipsec transform-set ESP-3DES-MD5 esp-3des esp-md5-hmac
crypto ipsec security-association lifetime seconds 28800
crypto ipsec security-association lifetime kilobytes 4608000
crypto isakmp enable inside
crypto isakmp enable outside
telnet xx.xxx.xxx.xx 255.255.0.0 inside
telnet xx.xxx.xxx.xx 255.255.255.0 inside
telnet xx.xxx.xxx.xx 255.255.255.0 inside
telnet xx.xxx.xxx.xx 255.255.255.224 inside
telnet xx.xxx.xxx.xx 255.255.255.248 inside
telnet timeout 15
ssh timeout 5
console timeout 0
management-access inside
dhcpd auto_config outside
!
dhcpd address xx.xxx.xxx.xx - xx.xxx.xxx.xx inside
dhcpd dns 172.xx.x.x2 172.xx.x.x1 interface inside
dhcpd wins 172.xx.x.x1 172.xx.x.x2 interface inside
dhcpd domain xxxxxx.com interface inside
dhcpd option 176 ascii mcipadd=xx.xx.xx.xx,xx.xx.xx.xx,mcport=1719,httpsrvr=xx.xx.xx.xx,httpdir=IPSettings interface inside
dhcpd option 242 ascii mcipadd=xx.xx.xx.xx,xx.xx.xx.xx,mcport=1719,httpsrvr=xx.xx.xx.xx,httpdir=IPSettings interface inside
dhcpd enable inside
!
vpnclient server xx.xxx.xx.xx
vpnclient mode network-extension-mode
vpnclient nem-st-autoconnect
vpnclient vpngroup XXXXXXXXXXXXX password ********
vpnclient username XXXXXXXXXXXXX password ********
vpnclient enable
threat-detection basic-threat
threat-detection statistics port
threat-detection statistics protocol
threat-detection statistics access-list
no threat-detection statistics tcp-intercept
ntp server 172.xx.x.x2 source inside prefer
username XXXXXXXX password XXXXXXXXXXXX encrypted privilege 15
!
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:XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
: end
asdm image disk0:/asdm-613.bin
no asdm history enable

I know there must be a command that I'm missing, just don't know what.

Any help would be appreciated.

Jim

 

[Supergrrover]

Either make the 2nd DNS server in your "dhcpd dns" command an external server or configure dns separately on each pc (You can do several dns servers in order.)

Brent
Systems Engineer / Consultant
CCNP, CCSP

 

[TechJimF]

Can this section be used?

dns server-group DefaultDNS
name-server 172.xx.x.x2
name-server 172.xx.x.x1
domain-name xxxxxx.com

Add external servers to this group then have:

dhcpd dns 172.xx.x.x2 172.xx.x.x1 interface inside

point to the ASA default gateway to provide DNS from the 'DefaultDNS' list.
colored text
Thanks,

Jim

 

[Supergrrover]

ASA doesn't do DNS resolution for clients.

That command is for the ASA itself.

http://www.cisco.com/en/US/docs/security/asa/asa82/configuration/guide/basic.html#wp1080248

Brent
Systems Engineer / Consultant
CCNP, CCSP

 

[TechJimF]

Changed the 2nd DNS entry to an external DNS server in the 'DHCPD'. Worked fine.

Thanks,

Jim