topic Re: Using DMZ to connect to internet in Network Security

Using DMZ to connect to internet

Trond Husoe — Tue, 12 Mar 2019 00:18:43 GMT

I am having problems accessing the internet when changing route from using outside to DMZ to access the internet. Reason for this change is because I have a FTP-server in DMZ that also needs access to the internet through DMZ.

The main server has two NICs and so I am routing default gw through the inside. I have tried to change default gateway to the DMZ-nic, but then I loose connection to the internet...

The ftp-server is a virtual maching running on the main server.

I have attached two nics to the FTP-server, but I can remove the last one.

I have a base license.

The configuration is as following:

# show run

: Saved

ASA Version 8.4(2)

hostname ciscoasa

domain-name inside-sport.no

enable password XXXXXXXXXXXXXXXXX encrypted

passwd XXXXXXXXXXXXXXXXX encrypted

names

interface Ethernet0/0

switchport access vlan 2

speed 100

duplex full

interface Ethernet0/1

interface Ethernet0/2

interface Ethernet0/3

interface Ethernet0/4

interface Ethernet0/5

switchport access vlan 12

interface Ethernet0/6

interface Ethernet0/7

interface Vlan1

nameif inside

security-level 100

ip address 192.168.1.1 255.255.255.0

interface Vlan2

nameif outside

security-level 0

ip address dhcp

interface Vlan12

no forward interface Vlan1

nameif DMZ

security-level 50

ip address 192.168.2.1 255.255.255.0

ftp mode passive

clock timezone CEST 1

clock summer-time CEDT recurring last Sun Mar 2:00 last Sun Oct 3:00

dns domain-lookup inside

dns domain-lookup outside

dns domain-lookup DMZ

dns server-group DefaultDNS

name-server 193.75.75.75

name-server 192.168.1.11

name-server 192.168.1.12

name-server 193.75.75.193

domain-name inside-sport.no

same-security-traffic permit intra-interface

object network obj_any

subnet 0.0.0.0 0.0.0.0

object network inside-net

subnet 192.168.1.0 255.255.255.0

object network NETWORK_OBJ_10.10.10.0_28

subnet 10.10.10.0 255.255.255.240

object network NETWORK_OBJ_192.168.1.128_27

subnet 192.168.1.128 255.255.255.224

object network NETWORK_OBJ_192.168.1.0_24

subnet 192.168.1.0 255.255.255.0

object network NETWORK_OBJ_192.168.254.0_28

subnet 192.168.254.0 255.255.255.240

object network dmz-ftpserver

host 192.168.2.101

description FTP server Host Object

object network dmz-webserver

host 192.168.2.100

description Web Server Host Object

object network ftp-server

object service FTP

service tcp source eq ftp

object service WWW

service tcp source eq www

object network DMZ.net

subnet 192.168.2.0 255.255.255.0

object-group protocol TCPUDP

protocol-object udp

protocol-object tcp

object-group network NET-VPNPOOL

network-object 173.194.32.34 255.255.255.0

access-list outside_access_in extended permit tcp any host 192.168.2.101 eq ftp

access-list outside_access_in extended permit tcp any host 192.168.2.100 eq www

access-list VPN-INSIDE-SPORT_splitTunnelAcl standard permit 192.168.1.0 255.255.255.0

access-list inside_access_dmz extended permit tcp any object DMZ.net range 1 65535

pager lines 24

logging enable

logging asdm informational

mtu inside 1500

mtu outside 1500

mtu DMZ 1500

ip local pool VPN-Pool 192.168.254.1-192.168.254.10 mask 255.255.255.0

icmp unreachable rate-limit 1 burst-size 1

no asdm history enable

arp timeout 14400

nat (DMZ,outside) source static dmz-webserver interface service WWW WWW

nat (DMZ,outside) source static dmz-ftpserver interface service FTP FTP

nat (inside,outside) source static any any destination static NETWORK_OBJ_10.10.10.0_28 NETWORK_OBJ_10.10.10.0_28 no-proxy-arp route-lookup

nat (inside,outside) source static any any destination static NETWORK_OBJ_192.168.1.128_27 NETWORK_OBJ_192.168.1.128_27 no-proxy-arp route-lookup

nat (inside,outside) source static NETWORK_OBJ_192.168.1.0_24 NETWORK_OBJ_192.168.1.0_24 destination static NETWORK_OBJ_192.168.254.0_28 NETWORK_OBJ_192.168.254.0_28 no-proxy-arp route-lookup

nat (outside,outside) source dynamic NET-VPNPOOL interface

object network obj_any

nat (inside,outside) dynamic interface

object network inside-net

nat (inside,outside) dynamic interface

object network DMZ.net

nat (DMZ,outside) dynamic interface

access-group outside_access_in in interface outside

access-group inside_access_dmz in interface DMZ

route outside 0.0.0.0 0.0.0.0 173.194.32.34 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 enable console LOCAL

aaa authentication http console LOCAL

aaa authentication ssh console LOCAL

aaa authorization command LOCAL

aaa authorization exec authentication-server

http server enable

http 192.168.1.0 255.255.255.0 inside

http 192.168.1.1 255.255.255.255 outside

no snmp-server location

no snmp-server contact

snmp-server enable traps snmp authentication linkup linkdown coldstart warmstart

crypto ipsec ikev1 transform-set ESP-3DES-SHA esp-3des esp-sha-hmac

crypto ipsec ikev1 transform-set ESP-AES-256-MD5 esp-aes-256 esp-md5-hmac

crypto ipsec ikev1 transform-set ESP-DES-SHA esp-des esp-sha-hmac

crypto ipsec ikev1 transform-set ESP-DES-MD5 esp-des esp-md5-hmac

crypto ipsec ikev1 transform-set ESP-AES-192-MD5 esp-aes-192 esp-md5-hmac

crypto ipsec ikev1 transform-set ESP-3DES-MD5 esp-3des esp-md5-hmac

crypto ipsec ikev1 transform-set ESP-AES-256-SHA esp-aes-256 esp-sha-hmac

crypto ipsec ikev1 transform-set ESP-AES-128-SHA esp-aes esp-sha-hmac

crypto ipsec ikev1 transform-set ESP-AES-192-SHA esp-aes-192 esp-sha-hmac

crypto ipsec ikev1 transform-set ESP-AES-128-MD5 esp-aes esp-md5-hmac

crypto dynamic-map SYSTEM_DEFAULT_CRYPTO_MAP 65535 set pfs

crypto dynamic-map SYSTEM_DEFAULT_CRYPTO_MAP 65535 set ikev1 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 ca trustpoint _SmartCallHome_ServerCA

crl configure

crypto ca certificate chain _SmartCallHome_ServerCA

certificate ca 6ecc7aa5a7032009b8cebcf4e952d491

308205ec 308204d4 a0030201 0202106e cc7aa5a7 032009b8 cebcf4e9 52d49130

0d06092a 864886f7 0d010105 05003081 ca310b30 09060355 04061302 55533117

30150603 55040a13 0e566572 69536967 6e2c2049 6e632e31 1f301d06 0355040b

13165665 72695369 676e2054 72757374 204e6574 776f726b 313a3038 06035504

0b133128 63292032 30303620 56657269 5369676e 2c20496e 632e202d 20466f72

20617574 686f7269 7a656420 75736520 6f6e6c79 31453043 06035504 03133c56

65726953 69676e20 436c6173 73203320 5075626c 69632050 72696d61 72792043

65727469 66696361 74696f6e 20417574 686f7269 7479202d 20473530 1e170d31

30303230 38303030 3030305a 170d3230 30323037 32333539 35395a30 81b5310b

30090603 55040613 02555331 17301506 0355040a 130e5665 72695369 676e2c20

496e632e 311f301d 06035504 0b131656 65726953 69676e20 54727573 74204e65

74776f72 6b313b30 39060355 040b1332 5465726d 73206f66 20757365 20617420

68747470 733a2f2f 7777772e 76657269 7369676e 2e636f6d 2f727061 20286329

3130312f 302d0603 55040313 26566572 69536967 6e20436c 61737320 33205365

63757265 20536572 76657220 4341202d 20473330 82012230 0d06092a 864886f7

0d010101 05000382 010f0030 82010a02 82010100 b187841f c20c45f5 bcab2597

a7ada23e 9cbaf6c1 39b88bca c2ac56c6 e5bb658e 444f4dce 6fed094a d4af4e10

9c688b2e 957b899b 13cae234 34c1f35b f3497b62 83488174 d188786c 0253f9bc

7f432657 5833833b 330a17b0 d04e9124 ad867d64 12dc744a 34a11d0a ea961d0b

15fca34b 3bce6388 d0f82d0c 948610ca b69a3dca eb379c00 48358629 5078e845

63cd1941 4ff595ec 7b98d4c4 71b350be 28b38fa0 b9539cf5 ca2c23a9 fd1406e8

18b49ae8 3c6e81fd e4cd3536 b351d369 ec12ba56 6e6f9b57 c58b14e7 0ec79ced

4a546ac9 4dc5bf11 b1ae1c67 81cb4455 33997f24 9b3f5345 7f861af3 3cfa6d7f

81f5b84a d3f58537 1cb5a6d0 09e4187b 384efa0f 02030100 01a38201 df308201

db303406 082b0601 05050701 01042830 26302406 082b0601 05050730 01861868

7474703a 2f2f6f63 73702e76 65726973 69676e2e 636f6d30 12060355 1d130101

ff040830 060101ff 02010030 70060355 1d200469 30673065 060b6086 480186f8

45010717 03305630 2806082b 06010505 07020116 1c687474 70733a2f 2f777777

2e766572 69736967 6e2e636f 6d2f6370 73302a06 082b0601 05050702 02301e1a

1c687474 70733a2f 2f777777 2e766572 69736967 6e2e636f 6d2f7270 61303406

03551d1f 042d302b 3029a027 a0258623 68747470 3a2f2f63 726c2e76 65726973

69676e2e 636f6d2f 70636133 2d67352e 63726c30 0e060355 1d0f0101 ff040403

02010630 6d06082b 06010505 07010c04 61305fa1 5da05b30 59305730 55160969

6d616765 2f676966 3021301f 30070605 2b0e0302 1a04148f e5d31a86 ac8d8e6b

c3cf806a d448182c 7b192e30 25162368 7474703a 2f2f6c6f 676f2e76 65726973

69676e2e 636f6d2f 76736c6f 676f2e67 69663028 0603551d 11042130 1fa41d30

1b311930 17060355 04031310 56657269 5369676e 4d504b49 2d322d36 301d0603

551d0e04 1604140d 445c1653 44c1827e 1d20ab25 f40163d8 be79a530 1f060355

1d230418 30168014 7fd365a7 c2ddecbb f03009f3 4339fa02 af333133 300d0609

2a864886 f70d0101 05050003 82010100 0c8324ef ddc30cd9 589cfe36 b6eb8a80

4bd1a3f7 9df3cc53 ef829ea3 a1e697c1 589d756c e01d1b4c fad1c12d 05c0ea6e

b2227055 d9203340 3307c265 83fa8f43 379bea0e 9a6c70ee f69c803b d937f47a

6decd018 7d494aca 99c71928 a2bed877 24f78526 866d8705 404167d1 273aeddc

481d22cd 0b0b8bbc f4b17bfd b499a8e9 762ae11a 2d876e74 d388dd1e 22c6df16

b62b8214 0a945cf2 50ecafce ff62370d ad65d306 4153ed02 14c8b558 28a1ace0

5becb37f 954afb03 c8ad26db e6667812 4ad99f42 fbe198e6 42839b8f 8f6724e8

6119b5dd cdb50b26 058ec36e c4c875b8 46cfe218 065ea9ae a8819a47 16de0c28

6c2527b9 deb78458 c61f381e a4c4cb66

quit

crypto ikev1 enable outside

crypto ikev1 policy 10

authentication pre-share

encryption 3des

hash sha

group 2

lifetime 86400

telnet timeout 5

ssh 192.168.1.0 255.255.255.0 inside

ssh 0.0.0.0 0.0.0.0 outside

ssh timeout 30

console timeout 0

management-access inside

no vpn-addr-assign aaa

no vpn-addr-assign dhcp

dhcpd domain inside-sport.no

dhcpd auto_config outside

dhcpd address 192.168.1.20-192.168.1.49 inside

dhcpd dns 192.168.1.11 192.168.1.12 interface inside

dhcpd domain inside-sport.no interface inside

dhcpd enable inside

threat-detection basic-threat

threat-detection statistics access-list

no threat-detection statistics tcp-intercept

webvpn

group-policy VPN-INSIDE-SPORT internal

group-policy VPN-INSIDE-SPORT attributes

dns-server value 192.168.1.11 193.75.75.193

vpn-tunnel-protocol ikev1

split-tunnel-policy tunnelspecified

split-tunnel-network-list value VPN-INSIDE-SPORT_splitTunnelAcl

default-domain value inside-sport.no

username foo password XXXXXXXXXXXXXXXXX encrypted privilege 15

tunnel-group VPN-INSIDE-SPORT type remote-access

tunnel-group VPN-INSIDE-SPORT general-attributes

address-pool VPN-Pool

default-group-policy VPN-INSIDE-SPORT

tunnel-group VPN-INSIDE-SPORT ipsec-attributes

ikev1 pre-shared-key *****

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

call-home reporting anonymous

call-home

profile CiscoTAC-1

no active

destination address http https://tools.cisco.com/its/service/oddce/services/DDCEService

destination address email callhome@cisco.com

destination transport-method http

subscribe-to-alert-group diagnostic

subscribe-to-alert-group environment

subscribe-to-alert-group inventory periodic monthly

subscribe-to-alert-group configuration periodic monthly

subscribe-to-alert-group telemetry periodic daily

Cryptochecksum:d0c94dce38e18ab6599ca05d641e8932

: end

ciscoasa(config)#

When running:

packet-tracer input DMZ icmp 172.16.4.51 8 0 4.2.2.2

I get this output:

Phase: 1

Type: ROUTE-LOOKUP

Subtype: input

Result: ALLOW

Config:

Additional Information:

in 0.0.0.0 0.0.0.0 outside

Phase: 2

Type: ACCESS-LIST

Subtype:

Result: DROP

Config:

Implicit Rule

Additional Information:

Result:

input-interface: DMZ

input-status: up

input-line-status: up

output-interface: outside

output-status: up

output-line-status: up

Action: drop

Drop-reason: (acl-drop) Flow is denied by configured rule

Route table on server connected to the inside:

# route -n

Kernel IP routing table

Destination Gateway Genmask Flags Metric Ref Use Iface

192.168.1.0 0.0.0.0 255.255.255.0 U 0 0 0 eth0

192.168.254.0 192.168.1.1 255.255.255.0 UG 0 0 0 eth0

192.168.2.0 0.0.0.0 255.255.254.0 U 0 0 0 eth1

0.0.0.0 192.168.2.1 0.0.0.0 UG 0 0 0 eth1

Route table for FTP-server in DMZ:

route -n

Kernel IP routing table

Destination Gateway Genmask Flags Metric Ref Use Iface

192.168.2.0 0.0.0.0 255.255.255.0 U 0 0 0 eth0

192.168.1.0 0.0.0.0 255.255.255.0 U 0 0 0 eth1

0.0.0.0 192.168.2.1 0.0.0.0 UG 0 0 0 eth0

Using DMZ to connect to internet

Jennifer Halim — Sun, 04 Nov 2012 01:34:16 GMT

A few things that need to be modified:

1) When running packet tracer, the source address must be your DMZ server IP (192.168.2.101), instead of 172.16.4.51.

2) To try ping, you would also need to configure icmp inspection:

policy-map global_policy

class inspection_default

inspect icmp

3) If you only need outbound connection to the internet from your ftp server, then you can remove this:

no nat (DMZ,outside) source static dmz-ftpserver interface service FTP FTP

Then "clear xlate"

4) This access-list is incorrect, looks like you applied that to the inside interface before, so if you are applying it to DMZ, it needs to change.

You can remove that access-list from the DMZ interface and you should be able to access the internet because if you don't need to restrict access from DMZ to internet, you don't have to configure any access-list:

no access-group inside_access_dmz in interface DMZ

Re: Using DMZ to connect to internet

Trond Husoe — Sun, 04 Nov 2012 11:46:25 GMT

1) Changed the IP address (what a Noob I am) to 192.168.2.101:

packet-tracer input DMZ icmp 192.168.2.101 8 0 4.2.2.2

Phase: 1

Type: ACCESS-LIST

Subtype:

Result: ALLOW

Config:

Implicit Rule

Additional Information:

MAC Access list

Phase: 2

Type: ROUTE-LOOKUP

Subtype: input

Result: ALLOW

Config:

Additional Information:

in 0.0.0.0 0.0.0.0 outside

Phase: 3

Type: ACCESS-LIST

Subtype:

Result: DROP

Config:

Implicit Rule

Additional Information:

Result:

input-interface: DMZ

input-status: up

input-line-status: up

output-interface: outside

output-status: up

output-line-status: up

Action: drop

Drop-reason: (acl-drop) Flow is denied by configured rule

2) OK - I'll consider that

3) All virtual servers (I believe there are 5 virtual linux servers or so in inside zone) need internet access + any laptops (currently three) that are in the network as well. So all machines in inside + dmz shall have outside access. In DMZ I have an FTP and a Web-server.

The www and the ftp would need to send in and out, right?

4) OK. I'll remove that one and report back.

Re: Using DMZ to connect to internet

Jennifer Halim — Sun, 04 Nov 2012 12:51:54 GMT

3) Do they need inbound access? ie: does user from the internet needs to FTP or web access your server?