topic 9.0.1 , dynamic nat problem with several nat rules in Network Security

9.0.1 , dynamic nat problem with several nat rules

dm — Tue, 12 Mar 2019 01:09:55 GMT

Hello!

I have my computer behind ASA dynamic nat:

object network obj-192.168.22.229

host 192.168.22.229

nat (inside,outside) source dynamic obj-192.168.22.229 interface

All works OK, and I have hosts with static nat, they work too.

then I need to give access to all users to some host , but only to http, so I add:

object network obj-192.168.0.0
 subnet 192.168.0.0 255.255.0.0

object service obj-tcp-eq-80

service tcp destination eq www

host we need to access ( this one is for test)

object network obj-66.7.199.108

host 66.7.199.108

and nat rule:

nat (inside,outside) source dynamic obj-192.168.0.0 interface destination static obj-66.7.199.108 obj-66.7.199.108 service obj-tcp-eq-80 obj-tcp-eq-80

OK, now users can access 66.7.199.108 port 80.

But I can't!

dm@dm:~$ telnet 66.7.199.108 80

Trying 66.7.199.108...

telnet: Unable to connect to remote host: Connection refused

The same is with static nat hosts.

If I disable

nat (inside,outside) source dynamic obj-192.168.0.0 interface destination static obj-66.7.199.108 obj-66.7.199.108 service obj-tcp-eq-80 obj-tcp-eq-80

or change it to

nat (inside,outside) source dynamic obj-192.168.0.0 interface destination static obj-66.7.199.108 obj-66.7.199.108

i.e. without port all is OK, but I need to limit access to port 80, and, afair, all was OK with 8.x.

Could you tell me how can I solve this problem?

Thank you!

9.0.1 , dynamic nat problem with several nat rules

Julio Carvajal — Tue, 05 Mar 2013 06:05:30 GMT

Hello,

Based on what you explain you are looking to filter traffic and for that we have ACL's, so no need to use NAT

access-list inside_outside permit tcp object obj-192.168.0.0 host 66.7.199.108 eq 80

access-list inside_outside deny ip object obj-192.168.0.0 host 66.7.199.108

access-list inside_outside permit ip any any

access-group inside_outside in interface outside

Regards

Re: 9.0.1 , dynamic nat problem with several nat rules

dm — Tue, 05 Mar 2013 06:11:21 GMT

Thank you!

Yes, sure, I can filter, but, really, more interesting thing why nat doesn't work as expected.

And I'd like to filter only natted traffic for these hosts, i.e. I don't want to limit my computer and/or static nats, etc.

Yes, it is possible to apply more complex filter, but...

Any ideas?

9.0.1 , dynamic nat problem with several nat rules

Julio Carvajal — Tue, 05 Mar 2013 06:20:09 GMT

Well, lets do something,

Can you share the show run nat ?

Also what is your IP address and what other IP's cannot access this host,

I would recommend you to do captures

capture capin interface inside match tcp host your_private_ip host server_public_ip eq 80 trace

Then generate some traffic from your PC and afterwards

do:

show cap capin

show cap capin trace packet-number 1

Share entire outputs please

9.0.1 , dynamic nat problem with several nat rules

dm — Tue, 05 Mar 2013 06:33:16 GMT

Here is

# show run nat

nat (inside,any) source static obj-192.168.42.128 obj-192.168.42.128 destination static obj-10.2.0.0 obj-10.2.0.0 no-proxy-arp

nat (inside,any) source static obj-192.168.42.128 obj-192.168.42.128 destination static obj-10.11.0.0 obj-10.11.0.0 no-proxy-arp

nat (inside,any) source static obj-192.168.200.198 obj-192.168.200.198 destination static obj-192.168.200.197 obj-192.168.200.197 no-proxy-arp

nat (inside,outside) source static obj-192.168.42.131 obj-88.80.32.211

nat (inside,outside) source static obj-192.168.42.130 obj-88.80.32.212

nat (inside,outside) source dynamic obj-192.168.22.231 interface

nat (inside,outside) source dynamic obj-192.168.0.0 interface destination static obj-84.52.87.98 obj-84.52.87.98

nat (inside,outside) source dynamic obj-192.168.0.0 interface destination static obj-87.249.230.101 obj-87.249.230.101 service obj-tcp-eq-3306 obj-tcp-eq-3306

nat (inside,outside) source dynamic obj-192.168.0.0 interface destination static obj-87.249.230.101 obj-87.249.230.101 service obj-tcp-eq-5555 obj-tcp-eq-5555

nat (inside,outside) source dynamic obj-192.168.0.0 interface destination static obj-87.249.230.101 obj-87.249.230.101 service obj-udp-eq-55777 obj-udp-eq-55777

nat (inside,outside) source dynamic obj-192.168.0.0 interface destination static obj-131.107.115.36 obj-131.107.115.36 service obj-tcp-eq-443 obj-tcp-eq-443

nat (inside,outside) source dynamic obj-192.168.0.0 interface destination static obj-89.111.181.74 obj-89.111.181.74 service obj-tcp-eq-3345 obj-tcp-eq-3345

nat (inside,outside) source dynamic obj-192.168.0.0 interface destination static obj-89.111.181.74 obj-89.111.181.74 service obj-tcp-eq-5690 obj-tcp-eq-5690

nat (inside,outside) source dynamic obj-192.168.0.0 interface destination static obj-89.111.181.74 obj-89.111.181.74 service obj-tcp-eq-4477 obj-tcp-eq-4477

nat (inside,outside) source dynamic obj-192.168.0.0 interface destination static obj-87.249.230.101 obj-87.249.230.101 service obj-tcp-eq-2226 obj-tcp-eq-2226

nat (inside,outside) source dynamic obj-192.168.0.0 interface destination static obj-87.249.230.101 obj-87.249.230.101 service obj-udp-eq-2226 obj-udp-eq-2226

nat (inside,outside) source dynamic obj-192.168.0.0 interface destination static obj-217.67.178.45 obj-217.67.178.45

nat (inside,outside) source dynamic obj-192.168.24.223 interface

nat (inside,outside) source dynamic obj-192.168.0.0 interface destination static obj-87.249.228.66 obj-87.249.228.66

nat (inside,outside) source dynamic obj-192.168.0.0 interface destination static obj-87.249.226.18 obj-87.249.226.18

nat (inside,outside) source dynamic obj-192.168.0.0 interface destination static obj-83.220.37.114 obj-83.220.37.114

nat (inside,outside) source dynamic obj-192.168.24.9 interface

nat (inside,outside) source dynamic obj-192.168.22.19 interface

nat (inside,outside) source dynamic obj-192.168.0.0 interface destination static obj-194.79.35.83 obj-194.79.35.83

nat (inside,outside) source dynamic obj-192.168.22.31 interface

nat (inside,any) source static obj-10.64.252.242 obj-10.64.252.242 destination static obj-10.64.252.241 obj-10.64.252.241 no-proxy-arp

nat (inside,outside) source static obj-192.168.22.202 obj-88.80.32.213

nat (inside,outside) source dynamic obj-192.168.24.8 interface

nat (inside,outside) source static obj-192.168.22.110 obj-88.80.32.214

nat (inside,outside) source dynamic obj-192.168.0.0 interface destination static obj-188.127.228.215 obj-188.127.228.215

nat (inside,outside) source dynamic obj-192.168.28.0 interface

nat (inside,outside) source dynamic obj-10.0.0.0 interface destination static obj-83.220.37.114 obj-83.220.37.114

nat (inside,outside) source dynamic obj-192.168.0.0 interface destination static obj-83.151.12.218 obj-83.151.12.218

nat (inside,outside) source static obj-192.168.42.135 obj-88.80.32.216

nat (inside,outside) source static obj-192.168.42.136 obj-88.80.32.217

nat (inside,any) source static obj-192.168.0.0 obj-192.168.0.0 destination static obj-192.168.214.0 obj-192.168.214.0 no-proxy-arp

nat (inside,any) source static obj-10.0.0.0 obj-10.0.0.0 destination static obj-192.168.214.0 obj-192.168.214.0 no-proxy-arp

nat (inside,any) source static obj-192.168.201.8 obj-192.168.201.8 destination static obj-192.168.201.9 obj-192.168.201.9 no-proxy-arp

nat (inside,any) source static obj-192.168.201.142 obj-192.168.201.142 destination static obj-192.168.201.141 obj-192.168.201.141 no-proxy-arp

nat (inside,outside) source dynamic obj-192.168.22.229 interface

nat (inside,outside) source dynamic obj-192.168.0.0 interface destination static obj-89.250.217.234 obj-89.250.217.234

nat (inside,outside) source dynamic obj-192.168.0.0 interface destination static obj-66.7.199.108 obj-66.7.199.108 service obj-tcp-eq-80 obj-tcp-eq-80

object network obj_any

nat (inside,outside) dynamic obj-0.0.0.0

I'll capture trafic and post it here 🙂

Thank you!

9.0.1 , dynamic nat problem with several nat rules

dm — Tue, 05 Mar 2013 06:37:28 GMT

here is trace

show cap capin

2 packets captured

1: 10:34:59.784841 192.168.22.229.52685 > 66.7.199.108.80: S 1509935962:1509935962(0) win 14600

2: 10:34:59.784902 66.7.199.108.80 > 192.168.22.229.52685: R 0:0(0) ack 1509935963 win 14600

2 packets shown

show cap capin trace packet-number 1

2 packets captured

1: 10:34:59.784841 192.168.22.229.52685 > 66.7.199.108.80: S 1509935962:1509935962(0) win 14600

1 packet shown

And what I got:

dm@dm:~$ telnet 66.7.199.108 80

Trying 66.7.199.108...

telnet: Unable to connect to remote host: Connection refused

9.0.1 , dynamic nat problem with several nat rules

Julio Carvajal — Tue, 05 Mar 2013 06:38:19 GMT

Hello,

nat (inside,outside) 2 source dynamic obj-192.168.0.0 interface destination static obj-66.7.199.108 obj-66.7.199.108 service obj-tcp-eq-80 obj-tcp-eq-80

Then try it and if it does not make a difference capture the traffic

9.0.1 , dynamic nat problem with several nat rules

dm — Tue, 05 Mar 2013 06:42:07 GMT

unfortunately, no difference 😞

show cap capin

2 packets captured

1: 10:41:10.420235 192.168.22.229.52717 > 66.7.199.108.80: S 2096723792:2096723792(0) win 14600

2: 10:41:10.420296 66.7.199.108.80 > 192.168.22.229.52717: R 0:0(0) ack 2096723793 win 14600

2 packets shown

show cap capin trace packet-number 1

2 packets captured

1: 10:41:10.420235 192.168.22.229.52717 > 66.7.199.108.80: S 2096723792:2096723792(0) win 14600

1 packet shown

Re: 9.0.1 , dynamic nat problem with several nat rules

dm — Tue, 05 Mar 2013 06:48:16 GMT

sorry, I forgot to remove previous rule 🙂 - user just called me and , you know...

Really, it works

dm@dm:~$ telnet 66.7.199.108 80

Trying 66.7.199.108...

Connected to 66.7.199.108.

Escape character is '^]'.

Thank you!

Could you explain me what we did? 🙂

Re: 9.0.1 , dynamic nat problem with several nat rules

Julio Carvajal — Tue, 05 Mar 2013 12:50:24 GMT

Hello,

The list was almost at the bottom so we just add at the top so it take precedence,

That's it

Regards