Need help with DMZ access lists

Jason Flory — Tue, 12 Mar 2019 00:53:25 GMT

Hello Everyone

I have just setup a new ASA 5525 and am configuring DMZ. As a test i have been able to successfully publish web and rdp from outside to inside and from outside to DMZ. My internal clients can successfullly communicate with DMZ hosts. Where I am running into problems is allowing the DMZ host access to internal resources. Whenever i apply an access list the DMZ interface it then blocks access to the outside interface because of the implicit deny. What i want is to be able give DMZ hosts access to internal resouces but also be able to allow then access to the internet for basic http https.

Question is how do i give hosts granular access to internal resouces from the DMZ without killing their acces to the outside.

Currently from outside i can access both DMZ host and internal host on port 80 and 3389. From DMZ i can access internal host on port 80 but cannot access external resouces on outside interface.

Thanks

Here is my config

hostname SFN-ASA1

domain-name ia-global.com

enable password xxxxxxxxx encrypted

passwd xxxxxxxxxxxx encrypted

names

interface GigabitEthernet0/0

nameif outside

security-level 0

ip address x.x.x.34 255.255.255.224

interface GigabitEthernet0/1

nameif Inside

security-level 100

ip address 10.2.0.3 255.255.255.248

interface GigabitEthernet0/2

nameif dmz

security-level 50

ip address 172.16.29.1 255.255.255.0

interface GigabitEthernet0/3

shutdown

no nameif

no security-level

no ip address

interface GigabitEthernet0/4

shutdown

no nameif

no security-level

no ip address

interface GigabitEthernet0/5

shutdown

no nameif

no security-level

no ip address

interface GigabitEthernet0/6

shutdown

no nameif

no security-level

no ip address

interface GigabitEthernet0/7

shutdown

no nameif

no security-level

no ip address

interface Management0/0

shutdown

nameif management

security-level 100

ip address 10.2.3.20 255.255.255.0

management-only

ftp mode passive

clock timezone PST -8

clock summer-time PDT recurring

dns domain-lookup Inside

dns server-group DefaultDNS

name-server 10.2.3.21

name-server 10.2.3.22

domain-name ia-global.com

object network test_rdp

host 10.2.0.4

object network obj_dmz_network

subnet 172.16.29.0 255.255.255.0

object network obj_dmz_server

host 172.16.29.5

object network objN_default_network

subnet 0.0.0.0 0.0.0.0

object service objS_rdp

service tcp source eq 3389 destination eq 3389

object network objN_inside

subnet 10.0.0.0 255.0.0.0

object-group service objS_outbound_protocols

description This group is used for all outbound protocols

service-object tcp destination eq www

service-object tcp destination eq https

service-object tcp destination eq ftp

service-object tcp destination eq ssh

service-object tcp destination eq 3389

service-object udp destination eq ntp

service-object icmp

access-list dmz_access extended permit tcp any object test_rdp eq www

access-list dmz_access extended permit tcp any object test_rdp eq 3389

access-list public_access extended permit tcp any object obj_dmz_server eq 3389

access-list public_access extended permit tcp any object test_rdp eq www

access-list public_access extended permit tcp any object obj_dmz_server eq www

pager lines 24

logging enable

logging asdm informational

mtu outside 1500

mtu Inside 1500

mtu management 1500

mtu dmz 1500

no failover

icmp unreachable rate-limit 1 burst-size 1

icmp permit any outside

icmp permit any Inside

icmp permit any dmz

no asdm history enable

arp timeout 14400

object network test_rdp

nat (Inside,outside) static 64.47.176.56

object network obj_dmz_network

nat (Inside,dmz) static obj_dmz_network

object network obj_dmz_server

nat (dmz,outside) static 64.47.176.58

object network objN_inside

nat (Inside,outside) dynamic interface

access-group public_access in interface outside

access-group dmz_access in interface dmz

route outside 0.0.0.0 0.0.0.0 x.x.x.33 1

route Inside 10.0.0.0 255.0.0.0 10.2.0.1 1

route Inside 192.168.0.0 255.255.0.0 10.2.0.1 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

timeout floating-conn 0:00:00

dynamic-access-policy-record DfltAccessPolicy

user-identity default-domain LOCAL

aaa authentication ssh console LOCAL

http server enable

http 10.0.0.0 255.0.0.0 Inside

http 192.168.0.0 255.255.0.0 Inside

http 192.168.0.0 255.255.0.0 management

http 10.2.3.0 255.255.255.0 Inside

http 10.2.3.0 255.255.255.0 management

no snmp-server location

no snmp-server contact

snmp-server enable traps snmp authentication linkup linkdown coldstart warmstart

telnet 10.0.0.0 255.0.0.0 Inside

telnet timeout 30

ssh 10.0.0.0 255.0.0.0 Inside

ssh timeout 30

console timeout 0

management-access Inside

threat-detection basic-threat

threat-detection statistics access-list

no threat-detection statistics tcp-intercept

ntp server 10.2.3.21

webvpn

username xxxxxx password xxxxxxxxxxx encrypted privilege 15

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

inspect icmp

service-policy global_policy global

prompt hostname context

no call-home reporting anonymous

Cryptochecksum:b115172d02c6c1286138d410287aaf87

: end

Re: Need help with DMZ access lists

Jennifer Halim — Tue, 29 Jan 2013 01:28:14 GMT

The following NAT is incorrect:

object network obj_dmz_network

nat (Inside,dmz) static obj_dmz_network

It should have been:

object network obj_10.0.0.0

subnet 10.0.0.0 255.0.0.0

nat (Inside,dmz) static obj_10.0.0.0

Then to provide granular access to the inside, you would need to place all the specific lines at the top of the ACL, then deny to 10.0.0.0, and finally permit any as follows:

access-list dmz_access permit tcp 172.16.29.0 255.255.255.0 10.0.0.0 255.0.0.0 eq 80

access-list dmz_access permit tcp 172.16.29.0 255.255.255.0 10.0.0.0 255.0.0.0 eq 443

...

access-list dmz_access deny ip 172.16.29.0 255.255.255.0 10.0.0.0 255.0.0.0

access-list dmz_access permit tcp 172.16.29.0 255.255.255.0 any eq 80

access-list dmz_access permit tcp 172.16.29.0 255.255.255.0 any eq 443

access-list dmz_access permit udp 172.16.29.0 255.255.255.0 any eq 53

Hope that helps.

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Need help with DMZ access lists

Re: Need help with DMZ access lists