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From Jayapal Reddy Uradi <>
Subject RE: StaticNAT, Portforwarding and FIrewall implemenation on the SRX
Date Fri, 12 Oct 2012 06:07:37 GMT

Please find my inline comments.



-----Original Message-----
From: Alena Prokharchyk 
Sent: Friday, October 12, 2012 5:54 AM
To:; Jayapal Reddy Uradi
Subject: Re: StaticNAT, Portforwarding and FIrewall implemenation on the SRX

Jayapal, I reviewed the spec. My comments:

If firewall rules per public IP address can't be configured on the SRX, and there is no way
to fix it (your spec says so in "Limitation" section), why do we introduce all this complexity?
To me it seems like we are trying to show the user that he is controlling public ports on
SRX, while in fact it's not true. It should work just like it used to work before: the Ingress
traffic flow from public to guest interfaces should be controlled by PF/StaticNat/LB rule;
Ingress traffic to public ip address is allowed always. When there is no PF/LB/StaticNat rule
for the Guest network port, the traffic to Guest port is blocked. Once you create PF rule
for publicIp
+ guestIp, the access to the specific port of the Guest network is 
+ opened
automatically. The example below (taken from the spec):


1. Acquire IP P1.
2. Create Firewall for port 22 - port 22.
3. Configure the port forwarding for Public IP P1, user VM V1 4. Acquire another IP P2.
5. Enable staticNAT on P2 for VM V1

Let me change the  case here  and going to update in FS.
6.Add firewall rule for P2 for VM V1 on ports 80
7. Now In SRX, using P2  user can access the VM V1 ports 22 and 80.

7. Now P1 and P2 both can access the VM port 22 - /// you haven't created the Firewall rule
for the P2, yet the access from it is enabled implicitly to 22:22 port. It's very confusing.
In other words, the firewall rule created for P1 ip should never ever control the access to
P2 ip address.

We need to fix the original issue - make StaticNat rules on the SRX. For that we have to treat
firewall rule as a static nat rule for a particular port by SRX device if the static nat is
enabled for this public ip address in the cloudStack. In all other cases Firewall rule should
be just ignored.

I agree with ignoring firewall for port forwarding.
But in VR the PF rule works only after adding  Firewall rule for the public ports.


* Get Ip1.
* Create PF rule for IP1 and port 22 VM1. Now you can access the Vm1.
* Create firewall rule for Ip1. SRX should just ignore this request as it will not do anything


* Get IP2
* Enable static nat on the IP2 and VM1. Nothing is sent to SRX just yet.
* Create firewall rule for IP2 and ports 22-23. Send enable static nat for
IP2/VM1 and port 22-23 to the SRX device
* Repeat last step for each port (port range) you want to enable static nat for.

In SRX,  below issue can still exist.
In addition to CASE1, CASE2,  Create another PF rule for IP1 and port 80 VM1. Now you can
access the Vm1 port 80.
Now P2 can access the port 80 without Firewall rule on Port 80.  Because security policy in
SRX  is not differentiated for 
Public IPs.

In other words, you have to make the translation of Firewall rule of the cloudStack to ConfigureStaticNat
on SRX when the targeted public IP address is Static nat enabled. In all other cases Firewall
commands should be just ignored by the SRX device.

Let me know what you think,
I agree with you.
Current port forwarding rule have Public Port range and Private Port range. 
So port forwarding allows only the Public Ports that we added. Again allowing Ports using
Firewall is of no use.
Port forwarding rule: public Ports 22 and private ports 22
Here Port Forwarding  can allow  only 22. so no need to explicitly add using the firewall
to allow
If you don't want to allow the ports DELETE the Port Forwarding rule.
On top of PF  adding Firewall rule to allow ports 22-80 of no use because there is port forwarding
rule for 23-80.


On 10/11/12 6:16 AM, "Jayapal Reddy Uradi" <>

>StaticNAT,  PortForwarding  and Firewall  current functionality  in SRX 
>is not similar to the  Virtual router.
>This functional spec describes  the what  configuration possible on the 
>SRX and also the limitation of SRX  compared to the  functionality in VR.
>Please find the functional spec here:
>Please provide your comments on configuring the SRX device to get 
>functionality  similar to  VR.

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