Question

Access Webserver on ASA DMZ from Inside

Asked by: spickles1

I've got an ASA5510 running 8.2(1) with a Webserver in the DMZ. The webserver can be accessed from outside just fine. But I cannot access our website from within. I can ping the private address from inside, but not the public ip. I can ping the public IP from outside. I see several posts indicating that a static NAT translation from INSIDE to INSIDE is recommended (i.e. keep the source and destination network the same). My firewall is in routed mode, so I chose to use a NAT exempt rule instead. An example would be trying to access my webserver (10.208.11.99 / 24) from a host on another Class A subnet (10.208.13.104 / 24). I am specifying all subnets on their VLSM, so my NAT exempt is NOT 10.0.0.0 / 8 <--> 10.0.0.0 / 8.

name 10.208.11.99 Webserver_Inside description Webserver
name 24.x.x.21 Webserver_Outside description Webserver Public IP
name 24.x.x.17 ASA5510_Outside description ASA5510 Public IP
!
interface Ethernet0/0
 nameif outside
 security-level 0
 ip address ASA5510_Outside 255.255.255.248 
!
interface Ethernet0/1
 nameif inside
 security-level 100
 ip address 192.168.0.10 255.255.255.252 
!
interface Ethernet0/2
 nameif dmz
 security-level 50
 ip address 10.208.11.1 255.255.255.0 
!
interface Ethernet0/3
 shutdown
 nameif management
 security-level 100
 ip address 1.1.1.1 255.255.255.0 
!
interface Management0/0
 shutdown
 no nameif
 no security-level
 no ip address
!
access-list inside_nat0_outbound extended permit ip object-group DM_INLINE_NETWORK_3 host Webserver_Inside 
access-list dmz_nat0_outbound extended permit ip host Webserver_Inside object-group DM_INLINE_NETWORK_4 
global (outside) 1 interface
global (dmz) 2 interface
nat (inside) 0 access-list inside_nat0_outbound
nat (inside) 1 0.0.0.0 0.0.0.0
nat (outside) 1 0.0.0.0 0.0.0.0
nat (dmz) 0 access-list dmz_nat0_outbound outside
static (dmz,outside) Webserver_Outside Webserver_Inside netmask 255.255.255.255 
static (inside,outside) Barracuda_Outside Barracuda_Inside netmask 255.255.255.255 
static (outside,inside) Barracuda_Inside Barracuda_Outside netmask 255.255.255.255 
static (dmz,inside) Webserver_Outside Webserver_Inside netmask 255.255.255.255 
access-group inside_access_in in interface inside
access-group outside_access_in in interface outside
access-group dmz_access_in in interface dmz
!
route outside 0.0.0.0 0.0.0.0 24.x.x.22 1

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Asked On: 2009-08-19 at 14:27:47ID24666463
Topics: Network Software Firewalls
,; Enterprise Firewalls
,; Cisco PIX Firewall
Participating Experts: 2
Points: 200
Comments: 8

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Answers

by: ccie22921Posted on 2009-08-19 at 15:46:58ID: 25138094

Can you provide output from
"show access-list dmz_access_in | include Webserver_Inside please?

by: nodiscoPosted on 2009-08-19 at 16:33:14ID: 25138295

Can you open the webserver using its internal ip from inside?

Do you have the following in your config?
same-security-traffic permit intra-interface

hth

by: spickles1Posted on 2009-08-19 at 18:14:59ID: 25138692

nodisco -

The same-security-traffic permit intra-interface got me last time, so yes, it's there. I can RDP to the webserver using its private IP address no problem. I suspect that I can't access our website internally with the private IP b/c we're enforcing the use of HTTP Headers on IIS 6.0.

ccie22921 -

I'll have to see if I can get that for you - I have not yet rebuilt the VPN connection, and I don't allow the firewall to be managed from any other interface than 'inside'.

Regards,
Scott

by: nodiscoPosted on 2009-08-19 at 18:21:17ID: 25138727

If you have an internal DNS server, the "quick" solution would be to put an A-record for your public website name pointing to the internal address. But if you cannot even browse it internally using the private ip, there is something stopping it. As per ccie22921 - if you can post your acls, it may become apparent

by: spickles1Posted on 2009-08-19 at 19:11:43ID: 25138916

nodisco -

You're probably starting to understand why I posted here - I could have done the DNS A-Record as well, but my internal domain is not the same suffix as our website and I don't know how to create an A-Record that would work when the DNS server is going to append the default domain name. Perhaps an alias would work? Anyways, here's the access-list configured for the DMZ:

asa-5510# show access-list dmz_access_in | include Webserver_Inside
access-list dmz_access_in line 1 extended permit udp host Webserver_Inside any object-group DM_INLINE_UDP_2 0x1b8ad051 
  access-list dmz_access_in line 1 extended permit udp host Webserver_Inside any eq domain (hitcnt=215) 0x7241d90a 
  access-list dmz_access_in line 1 extended permit udp host Webserver_Inside any eq ntp (hitcnt=15) 0xdc4a179a 
access-list dmz_access_in line 2 extended permit icmp any host Webserver_Inside object-group DM_INLINE_ICMP_2 0xc8d2aa1d 
  access-list dmz_access_in line 2 extended permit icmp any host Webserver_Inside echo (hitcnt=0) 0xf4d70ac1 
  access-list dmz_access_in line 2 extended permit icmp any host Webserver_Inside echo-reply (hitcnt=0) 0xd6057b4a 
access-list dmz_access_in line 3 extended permit icmp host Webserver_Inside any object-group DM_INLINE_ICMP_1 0x77458a9b 
  access-list dmz_access_in line 3 extended permit icmp host Webserver_Inside any echo (hitcnt=27937) 0x5327ff21 
  access-list dmz_access_in line 3 extended permit icmp host Webserver_Inside any echo-reply (hitcnt=203) 0x7db3d4be 
access-list dmz_access_in line 4 extended permit tcp host Webserver_Inside object-group DM_INLINE_NETWORK_1 object-group DM_INLINE_TCP_2 0x09cfbaaa 
  access-list dmz_access_in line 4 extended permit tcp host Webserver_Inside host DNS2 eq domain (hitcnt=0) 0xec689ffe 
  access-list dmz_access_in line 4 extended permit tcp host Webserver_Inside host DNS2 eq ldap (hitcnt=1160) 0xcc427f9b 
  access-list dmz_access_in line 4 extended permit tcp host Webserver_Inside host DNS1 eq domain (hitcnt=470) 0x4c4b58b6 
  access-list dmz_access_in line 4 extended permit tcp host Webserver_Inside host DNS1 eq ldap (hitcnt=3639) 0x7842699a 
  access-list dmz_access_in line 4 extended permit tcp host Webserver_Inside host DNS2 eq 3268 (hitcnt=1154) 0x15fd6852 
  access-list dmz_access_in line 4 extended permit tcp host Webserver_Inside host DNS1 eq 3268 (hitcnt=1107) 0x7119cc2e 
  access-list dmz_access_in line 4 extended permit tcp host Webserver_Inside host DNS2 eq 445 (hitcnt=291) 0xa4f3993e 
  access-list dmz_access_in line 4 extended permit tcp host Webserver_Inside host DNS1 eq 445 (hitcnt=735) 0xc196ffc7 
  access-list dmz_access_in line 4 extended permit tcp host Webserver_Inside host DNS2 eq netbios-ssn (hitcnt=1) 0x14456591 
  access-list dmz_access_in line 4 extended permit tcp host Webserver_Inside host DNS1 eq netbios-ssn (hitcnt=546) 0x6bb93d1f 
  access-list dmz_access_in line 4 extended permit tcp host Webserver_Inside host DNS2 eq 88 (hitcnt=2) 0x10e3a6e7 
  access-list dmz_access_in line 4 extended permit tcp host Webserver_Inside host DNS1 eq 88 (hitcnt=219) 0x01046e98 
  access-list dmz_access_in line 4 extended permit tcp host Webserver_Inside host DNS2 eq 135 (hitcnt=65) 0xf8ed7d96 
  access-list dmz_access_in line 4 extended permit tcp host Webserver_Inside host DNS1 eq 135 (hitcnt=233) 0xc76857ce 
  access-list dmz_access_in line 4 extended permit tcp host Webserver_Inside host DNS2 eq 1026 (hitcnt=31) 0x4857e92e 
  access-list dmz_access_in line 4 extended permit tcp host Webserver_Inside host DNS1 eq 1026 (hitcnt=309) 0x8f7da1c4 
access-list dmz_access_in line 5 extended permit tcp any host Webserver_Inside object-group DM_INLINE_TCP_1 0xde6ab0a9 
  access-list dmz_access_in line 5 extended permit tcp any host Webserver_Inside eq www (hitcnt=1) 0x2237dccc 
  access-list dmz_access_in line 5 extended permit tcp any host Webserver_Inside eq https (hitcnt=0) 0x40ce314d 
  access-list dmz_access_in line 5 extended permit tcp any host Webserver_Inside eq 8014 (hitcnt=0) 0xf11413b9 
  access-list dmz_access_in line 5 extended permit tcp any host Webserver_Inside eq 3389 (hitcnt=0) 0x1c78cbed 
access-list dmz_access_in line 6 extended permit udp host Webserver_Inside object-group DM_INLINE_NETWORK_1 object-group DM_INLINE_UDP_1 0xc177c879 
  access-list dmz_access_in line 6 extended permit udp host Webserver_Inside host DNS2 eq 389 (hitcnt=44) 0x527c918e 
  access-list dmz_access_in line 6 extended permit udp host Webserver_Inside host DNS2 eq domain (hitcnt=792) 0xede6b0d4 
  access-list dmz_access_in line 6 extended permit udp host Webserver_Inside host DNS1 eq 389 (hitcnt=451) 0x2f248190 
  access-list dmz_access_in line 6 extended permit udp host Webserver_Inside host DNS1 eq domain (hitcnt=38782) 0x50af48fb 
  access-list dmz_access_in line 6 extended permit udp host Webserver_Inside host DNS2 eq 88 (hitcnt=226) 0xe6f87195 
  access-list dmz_access_in line 6 extended permit udp host Webserver_Inside host DNS1 eq 88 (hitcnt=1864) 0xeb240f98 
  access-list dmz_access_in line 6 extended permit udp host Webserver_Inside host DNS2 eq netbios-ns (hitcnt=0) 0xaf48c6c0 
  access-list dmz_access_in line 6 extended permit udp host Webserver_Inside host DNS1 eq netbios-ns (hitcnt=177) 0x697a2d7d 
  access-list dmz_access_in line 6 extended permit udp host Webserver_Inside host DNS2 eq netbios-dgm (hitcnt=0) 0x6b55f246 
  access-list dmz_access_in line 6 extended permit udp host Webserver_Inside host DNS1 eq netbios-dgm (hitcnt=170) 0xb3eb7a86 
access-list dmz_access_in line 7 extended permit tcp host Webserver_Inside host EXCHANGE object-group DM_INLINE_TCP_3 0x48bde070 
  access-list dmz_access_in line 7 extended permit tcp host Webserver_Inside host EXCHANGE eq 691 (hitcnt=12) 0x94ae6678 
  access-list dmz_access_in line 7 extended permit tcp host Webserver_Inside host EXCHANGE eq www (hitcnt=554) 0x1dacce7a 
  access-list dmz_access_in line 7 extended permit tcp host Webserver_Inside host EXCHANGE eq 137 (hitcnt=0) 0x44b6b3e8 
  access-list dmz_access_in line 7 extended permit tcp host Webserver_Inside host EXCHANGE eq 1434 (hitcnt=0) 0x34d31ca6 
  access-list dmz_access_in line 7 extended permit tcp host Webserver_Inside host EXCHANGE eq 445 (hitcnt=8) 0xa8878eba 
  access-list dmz_access_in line 7 extended permit tcp host Webserver_Inside host EXCHANGE eq 10424 (hitcnt=148) 0xf26b784e 
  access-list dmz_access_in line 7 extended permit tcp host Webserver_Inside host EXCHANGE eq smtp (hitcnt=187) 0xd1cacf9b 
  access-list dmz_access_in line 7 extended permit tcp host Webserver_Inside host EXCHANGE range 6001 6004 (hitcnt=12) 0xf2f6d8ae 
  access-list dmz_access_in line 7 extended permit tcp host Webserver_Inside host EXCHANGE eq 135 (hitcnt=12) 0x0233bb8c 
  access-list dmz_access_in line 7 extended permit tcp host Webserver_Inside host EXCHANGE eq 1027 (hitcnt=2) 0xd1f83e48 
  access-list dmz_access_in line 7 extended permit tcp host Webserver_Inside host EXCHANGE eq netbios-ssn (hitcnt=4) 0xdd843012 
access-list dmz_access_in line 8 extended permit udp host Webserver_Inside host EXCHANGE eq 1434 (hitcnt=58) 0x27f3d3cc 
access-list dmz_access_in line 10 extended permit tcp host Webserver_Inside any object-group DM_INLINE_TCP_4 0x5983ed30 
  access-list dmz_access_in line 10 extended permit tcp host Webserver_Inside any eq 8014 (hitcnt=1321) 0xd2db3130 
  access-list dmz_access_in line 10 extended permit tcp host Webserver_Inside any eq www (hitcnt=931) 0x1375ae53 
  access-list dmz_access_in line 10 extended permit tcp host Webserver_Inside any eq https (hitcnt=15) 0x8a99044d 
  access-list dmz_access_in line 10 extended permit tcp host Webserver_Inside any eq 9100 (hitcnt=5) 0xd85091b3 
  access-list dmz_access_in line 10 extended permit tcp host Webserver_Inside any eq 2967 (hitcnt=4) 0x3efc7257 
  access-list dmz_access_in line 10 extended permit tcp host Webserver_Inside any eq ftp (hitcnt=3) 0x4e90df55 
  access-list dmz_access_in line 10 extended permit tcp host Webserver_Inside any eq domain (hitcnt=0) 0xef5aab9a 
access-list dmz_access_in line 12 extended permit tcp host Webserver_Inside object-group DM_INLINE_NETWORK_2 eq ftp 0x28a582d3 
  access-list dmz_access_in line 12 extended permit tcp host Webserver_Inside host Symantec_Live_Update_2 eq ftp (hitcnt=0) 0x5fe12172 
  access-list dmz_access_in line 12 extended permit tcp host Webserver_Inside host Symantec_Live_Update_3 eq ftp (hitcnt=0) 0x88c55c03 
  access-list dmz_access_in line 12 extended permit tcp host Webserver_Inside host Symantec_Live_Update_1 eq ftp (hitcnt=16) 0x821f1320 
asa-5510#

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by: spickles1Posted on 2009-08-19 at 19:17:41ID: 25138944

Also, if I perform a ping and/or traceroute to the public address, the ping isn't successful from within and I think the ACLs should allow it. The failure of the traceroute makes me think I've got a routing issue, but there's a proper default route and full routing table(s). If the default route configured wasn't working, we wouldn't even be able to surf the web (but we can).

by: spickles1Posted on 2009-08-20 at 09:06:25ID: 25144204

I can't use the hairpinning due to the fact that I already have a static translation for the webserver like so:

static (dmz,outside) 24.97.199.21 10.208.11.99 netmask 255.255.255.255

So when I attempt

static (inside,inside) 24.97.199.21 10.208.11.99 netmask 255.255.255.255

there's a conflict/violation. I'm sure this is normal, so it looks like I'll try DNS Doctoring next...

by: spickles1Posted on 2009-08-20 at 10:46:38ID: 25145222

DNS Doctoring worked and I can now access our website internally using our .com address.

Thanks to all who participated!

20120131-EE-VQP-002

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Access Webserver on ASA DMZ from Inside

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