Category Archives: Citrix Access Gateway Enterprise Edition


In 2008 I had a conversation with Jay Tomlin asking him if he would put in an enhancement for ICA Logging on the AGEE. Basically we wanted the ability to see the external IP Addresses of our customers coming through the Access Gateway. As you are likely aware, what you get in the logs are the IP Addresses bound to the workstation and not the external IP Address that they are coming through. In the last ten years, it has become increasingly rare for an end user to actually plug their computer directly into the internet and more often, they are proxied behind a Netgear, Cisco/Linksys, and Buffalo switch. This makes reporting on where the users are coming from somewhat challenging.

Somewhere between 9.2 and 9.3 the requested enhancement was added and it included other very nice metrics as well. The two syslog events I want to talk about are ICASTART and ICAEND.

The ICASTART event contains some good information in addition to the external IP. Below you see a sample of the ICASTART log.

12/09/2012:14:40:46 GMT ns 0-PPE-0 : SSLVPN ICASTART 540963 0 : Source – Destination – username:domainname mhayes:Xentrifuge – applicationName Desktop – startTime “12/09/2012:14:40:46 GMT” – connectionId 81d1

As you can see, if you are a log monger, this is a VERY nice log!! (Few can appreciate this) With the exception of the credentials everything is very easy to parse and place into those nice SQL Columns I like. If you have Splunk, parsing is even easier and you don’t have to worry about how the columns line up.

The ICAEND even actually has quite a bit more information and were it not for the need to report ICA Sessions in real time, this is the only log you will need. Below is the ICAEND log.

12/09/2012:14:41:12 GMT ns 0-PPE-0 : SSLVPN ICAEND_CONNSTAT 541032 0 : Source – Destination – username:domainname mhayes:Xentrifuge – startTime “12/09/2012:14:40:46 GMT” – endTime “12/09/2012:14:41:12 GMT” – Duration 00:00:26 – Total_bytes_send 9363 – Total_bytes_recv 587588 – Total_compressedbytes_send 0 – Total_compressedbytes_recv 0 – Compression_ratio_send 0.00% – Compression_ratio_recv 0.00% – connectionId 81d16

Again, another gorgeous log that is very easy to parse and put into some useful information.

Logging the Data:
So, this was going to be my inaugural Splunk blog but I didn’t get off my ass and so my eval of Splunk expired and I have to wait 30 days to use it again (file that under “phuck”). So today we will be going over logging the data with the standard KIWI/SQL (basically a poor man’s Splunk) method.

So the way we log the data, if you haven’t been doing this already, is we configure the Netscaler to send logs to the KIWI Syslog server and we use the custom data source within KIWI to configure a SQL Logging rule. We then create the table, parse the data with a parsing script and voila, instant business intelligence.

Creating the custom KIWI Rule:

First, create the rule “ICA-START/END” with a descriptive filter configured as you see below.

Next you will optionally configure a Display action but more importantly you will configure the Script that parses the data.

Paste the following text (Below) into a file named Script_Parse_AGEE-ICA.txt and save it in the scripts directory of your KIWI install.

Function Main()

Main = “OK”

Dim MyMsg
Dim UserName
Dim Application
Dim SourceIP
Dim DestinationIP
Dim StartTime
Dim EndTime
Dim Duration
Dim SentBytes
Dim RecBytes
Dim ConnectionID

With Fields

UserName = “”
Application = “”
SourceIP = “”
DestinationIP = “”
StartTime = “”
EndTime = “”    
Duration = “”
SentBytes = “”
RecBytes = “”
ConnectionID = “”

MyMsg = .VarCleanMessageText

If ( Instr( MyMsg, “ICAEND_CONNSTAT” ) ) Then
SrcBeg = Instr( MyMsg, “Source”) + 6
SrcEnd = Instr( SrcBeg, MyMsg, “:”)
SourceIP = Mid( MyMsg, SrcBeg, SrcEnd – SrcBeg)

DstBeg = Instr( MyMsg, “Destination”) + 11
DstEnd = Instr( DstBeg, MyMsg, “:”)
DestinationIP = Mid( MyMsg, DstBeg, DstEnd – DstBeg)

UserBeg = Instr( MyMsg, “domainname”) + 10
UserEnd = Instr( UserBeg, MyMsg, “-“)
UserName = Mid( MyMsg, UserBeg, UserEnd – UserBeg)

StartBeg = Instr( MyMsg, “startTime “) + 11
StartEnd = Instr( StartBeg, MyMsg, ” “)
StartTime = Mid( MyMsg, StartBeg, StartEnd – StartBeg)

EndBeg = Instr( MyMsg, “endTime “) + 9
EndEnd = Instr( EndBeg, MyMsg, ” “)
EndTime = Mid( MyMsg, EndBeg, EndEnd – EndBeg)

DurBeg = Instr( MyMsg, “Duration “) + 9
DurEnd = Instr( DurBeg, MyMsg, ” “)
Duration = Mid( MyMsg, DurBeg, DurEnd – DurBeg)

SentBeg = Instr( MyMsg, “Total_bytes_send “) + 17
SentEnd = Instr( SentBeg, MyMsg, ” “)
SentBytes = Mid( MyMsg, SentBeg, SentEnd – SentBeg)    

RecBeg = Instr( MyMsg, “Total_bytes_recv “) + 17
RecEnd = Instr( RecBeg, MyMsg, ” “)
RecBytes = Mid( MyMsg, RecBeg, RecEnd – RecBeg)

ConBeg = Instr( MyMsg, “connectionId”) +12
ConnectionID = Mid( MyMsg, ConBeg)

Application = “NA”

end if

If ( Instr( MyMsg, “ICASTART” ) ) Then
SrcBeg = Instr( MyMsg, “Source”) + 6
SrcEnd = Instr( SrcBeg, MyMsg, “:”)
SourceIP = Mid( MyMsg, SrcBeg, SrcEnd – SrcBeg)

DstBeg = Instr( MyMsg, “Destination”) + 11
DstEnd = Instr( DstBeg, MyMsg, “:”)
DestinationIP = Mid( MyMsg, DstBeg, DstEnd – DstBeg)

UserBeg = Instr( MyMsg, “domainname”) + 10
UserEnd = Instr( UserBeg, MyMsg, “-“)
UserName = Mid( MyMsg, UserBeg, UserEnd – UserBeg)

AppBeg = Instr( MyMsg, “applicationName”) + 15
AppEnd = Instr( AppBeg, MyMsg, “-“)
Application = Mid( MyMsg, AppBeg, AppEnd – AppBeg)    

StartBeg = Instr( MyMsg, “startTime “) + 11
StartEnd = Instr( StartBeg, MyMsg, ” “)
StartTime = Mid( MyMsg, StartBeg, StartEnd – StartBeg)

ConBeg = Instr( MyMsg, “connectionId”) +12
ConnectionID = Mid( MyMsg, ConBeg)

EndTime = “NA”
Duration = “NA”
SentByes = “NA”    
RecBytes = “NA”

end if

.VarCustom01 = UserName
.VarCustom02 = Application
.VarCustom03 = SourceIP
.VarCustom04 = DestinationIP
.VarCustom05 = StartTime
.VarCustom06 = EndTime
.VarCustom07 = Duration
.VarCustom08 = SentBytes
.VarCustom09 = RecBytes
.VarCustom10 = ConnectionID

End With

End Function

Next you will create the custom DB format exactly as follows:
(IMPORTANT: NOT SHOWN Make sure you check “MsgDateTime” in this dialog box near the top)

Then you will create a new “Action” called “Log to SQL” and select the Custom DB Format and name the table AGEE_ICA and select “Create Table”. If you have not yet, build your connect string by clicking the box with the three periods at the top “…”

Then watch for ICASTART and ICAEND instances.

Then look at the data in your SQL Server:

Now you can report in real-time on external utilization by the following:

  • Utilization by IP Range
  • Utilization by Domain
  • Utilization by UserID
  • Utilization by time of day
  • Average Session Duration
  • You can tell if someone worked or not (“Yeah, I was on Citrix from 9AM to 5PM”)

Most of the queries you can reverse engineer from Edgesight Under the hood but if there is a specific query you are after just email me.

I get the average session duration with the following query:

avg(datepart(mi,cast([duration] as datetime)))
from syslog.dbo.agee_ica
where duration <> ‘NA’

 I tried to put everything in one table as you can see from the SQL Data Columns and the parsing script but you can split it up into separate tables if you want.

Thanks for reading!



Gratuitous Speculation: Cisco looks at Acquiring Netscaler from Citrix

Today istockanalyst and Network World speculated that Cisco would acquire the Citrix Networking (formerly ANG) line of products. Since the acquisition in 2003, Citrix has tried to brand itself as a Networking company AND a virtualization company. I recall talking with my Sales Manager and hearing her tell me how she needed to try to sell Netscalers to our incumbent Networking team where I was working at the time.

I have often referred to Network teams in organizations as the “Cisco Mafia” and explained to her that talking to the Network team about anything that was not F5, Juniper or Cisco may not bear a great deal of fruit. I recall several battles just to get my Netscalers implemented because I was “Load Balancing” on something other than Cisco and F5. I explained to them that what I had was a “Layer 7 switch” and that calling it a load balancer is a misnomer. The Netscaler is so many more things than just a load balancer.

Why this might be a bad thing?
Well, that depends, if this is a true acquisition meaning CISCO now “owns” Netscaler I worry what happens to the innovation after the acquisition. The fact is Cisco struggled in this space, at least to beat out Citrix and Big IP. I think this is due largely to the “Networking” mentality and Cisco’s inability to innovate beyond layer 3-4. I am NOT down on Network engineers and I have mad respect for their abilities but I have to point out that the ADC is its own hybrid skill set. Discussions such as Context Switching, XML Cross Site Scripting protection and URL Rewrites are not every day conversations for the guys running your Network. As the ADC has matured, the hybrid skill set needed to support it has also broadened. This has become a bit of a challenge in what seems to be (at least as a grey haired IT guy seeing next generation come in) a world of “specialists”. Can Cisco continue the innovation that exists with the market leaders in this space? If they could, why are they phasing out ACE? Are they even interested in it? If it is true that this will become a 2 billion dollar market, that may be the case. If not, does the Netscaler become another CSS or ACE? The reality is, a lot of companies have the “if you can’t beat ’em, buy ’em” mentality but my worries are what will happen afterward. $2 billion may be all the motivation they need.

Why this might be a good thing?
If this is truly an OEM agreement this could be fantastic for Citrix. I remember when Citrix first started selling Netscalers and I think one of the misunderstood dynamics by the Citrix brass was that they were sending their sales staff into just another meeting. “These aren’t my people” I recall one SE saying. I have fought more than one battle over Netscalers that would not have been necessary had they sported a sleek green Cisco bezel on them. The fact is, when enterprise networking is discussed, as stated, Citrix is the “kid doing his own thing” for those of you who grew up watching Sesame street. They are generally not in the conversation like Cisco, BigIP and Juniper are. Server sales vendors will always be outsiders to networking groups. Oddly, the UCS seems to be widely accepted by server teams but for some reason, it just isn’t the other way around.

Cisco partners and sales engineers can offer a bridge to these Networking groups. The biggest challenge is going to be how they sell it. It isn’t quite as easy as just putting a Cisco bezel on the Netscaler. You still have a great product in F5 and Cisco sales engineers will need to be able to go toe to toe with the current market share leader in that space. Ultimately, not having a stranger in the room may be just what Citrix needs to seize the lion’s share of what is predicted to be a $2 billion dollar market.

Thanks for reading!


Project Poindexter:VPN Logs

Total Information Awareness with your Netscaler/AGEE

Harvesting VPN Logs with the Netscaler:
When I first heard about Total Information Awareness I was a little concerned. Like a lot of my current team, I am one of those libertarians who really isn’t keen on his personal life being correlated and analyzed and a program that is overseen by unelected officials. That said, as an individual responsible for the security and integrity of information systems as well as a person who’s own personally identifiable information is in the databases of my bank, doctor and employer, I do believe I am entitled to know what is going on and I would like to think the stewards of my information are also informed of what is going on with regards to my own data. For this reason, I decided to start looking into how I could better monitor activity on my Netscaler and I wanted to provide an accompanying guide to my SCIFNET post/video showing how you can compartmentalize sensitive data using the VPX or a regular MPX class Netscaler.

Most engineers are fully aware that the Netscaler platform is capable of sending information to a syslog server. This in and of itself is not that significant as many network/Unix based appliances can syslog. What I want to discuss in this post is how to use a very cheap syslog server to set up a fully functional log consolidation system that includes parsing specific records and writing them to a relational database.

I find a certain amount of frustration with today’s six figure price tag event correlation systems and if you can only respond to a breach by doing “Find and Next” on a 90GB ASCII file, needless to say, that is not the most agile way to respond and not where it needs to be to react to an INFOSEC related incident. As with the Admiral Poindexter’s vision, proper analysis of events can be an instrumental tool in the defense of your information systems.

Below is an example of a typical VPN log from your Netscaler/AGEE appliance:
06/15/2010:05:59:38 ns PPE-0 : SSLVPN HTTPREQUEST 94167 : Context wireless@ – SessionId: 5- User wireless : Group(s) SCIF-NET USERS : Vserver – 06/15/2010:05:59:38 GET /service/getUpdate.xml?clientGUID=01BACADF-CE85-48CD-8270-B8A183C27464&VEOH_GUIDE_AUTH=am1zYXpib3k6MTI3ODAyODkyMTM1NzpyZWdp – –

Using KIWI Syslog server’s parsing capability, I will actually parse this data and write it into a SQL Server database to allow for very easy queries and eventually dashboards showing accountability and key data.

I have had engineers ask me how to get things like Client IP Address and what they have accessed. I will provide a parsing script that will pull from the example above, the following: (As in the case of the log above)

Context: wireless@
Payload: GET /service/getUpdate.xml?clientGUID=01BACADF-CE85-48CD-8270
*I have also included “Assigned_IP” in case any of you assign ip addresses instead of NATing. If you are able to get the Destination of where a user was going, the need to account for every IP Address may become less important but some folks insist on not NATing their users. If so, the parse script will grab their IP’s as well.

And just to show you that I do have the data you can see in the screen print below of the SQL Query:

Uh, John…who cares?
Well, most of the time you really shouldn’t need to do a lot of tracking of where your users are going but in some higher security environments being able to account for where users have gone could be very important. Say you hosted (a site I hate but for the purpose of this lab, their malware…err…client was installed on the laptop I was testing with) and someone said that the system had been compromised. You could immediately obtain every user ID and IP Address that accessed that site and what the payload that they ran against it was. You would see the XSS or SQL Injection string immediately. You would also note a system that had malware and was trying to get in over one of the SMB “Whipping boys” (445, 135-139).

Parsing data vs. just throwing it all into a flat file and waiting for an auditor to ask for it?
As I stated previously, the ability to have your data in a relational database can give you a number of advantages, not just pretty tables and eventually dashboards but you also open the door to the following:

  • Geospatial analysis of incoming IP Addresses (by cross referencing context with geospatial data from or other free geospatial ip-to-location data.
  • An actual count of the number of concurrent users on a system within a block of time including historical reporting and trending.
  • The number of times a “Deny” policy has been tripped and who tripped it. If you are compartmentalizing your data and you want to know who tried to access something they are not allowed to.
  • Your sensitive data is on wiki leaks and you want to know every user who accessed the resource the data resides on, when and what ports they used?
  • And lastly, find out who is going ” \\webserver\c$” to your web server instead of “http://webserver&#8221;

So what do I log?
Well, I log basically everything but for VPN I log three different events into two different tables, I log all HTTP based traffic, normal UDP/TCP based connections and I also have a separate table for all of my “DENIED_BY_POLICY” Events.

Here is an example of an HTTPREQUEST log:
06/15/2010:11:59:58 ns PPE-0 : SSLVPN HTTPREQUEST 110352 : Context wireless@ – SessionId: 5- User wireless : Group(s) SCIF-NET USERS : Vserver – 06/15/2010:11:59:58 GET /service/getUpdate.xml?clientGUID=01BACADF-CE85-48CD-8270-B8A183C27464&VEOH_GUIDE_AUTH=am1zYXpib3k6MTI3ODAyODkyMTM1NzpyZWdp – –

Here is an example of TCP/UDPFlow statistics:
06/15/2010:12:18:16 ns PPE-0 : SSLVPN UDPFLOWSTAT 111065 : Context wireless@ – SessionId: 5- User wireless – Client_ip – Nat_ip – Vserver – Source – Destination – Start_time “06/15/2010:12:15:32 ” – End_time “06/15/2010:12:18:16 ” – Duration 00:02:44 – Total_bytes_send 1729 – Total_bytes_recv 0 – Access Allowed – Group(s) “SCIF-NET USERS”

Here is an example of a DENIED_BY_POLICY event: (Over HTTP)
06/15/2010:10:17:14 ns PPE-0 : SSLVPN HTTP_RESOURCEACCESS_DENIED 106151 : Context wireless@ – SessionId: 5- User wireless – Vserver – Total_bytes_send 420 – Remote_host – Denied_url POST /tracker/update.jsp – Denied_by_policy “Problem-Site” – Group(s) “SCIF-NET USERS”

Let’s talk a little about the “DENIED_BY_POLICY” logs

Here is a Scenario: I have a problem website that I do not want any of my users to go to so I create a policy called “Problem-Site” denying access to the IP of the problem site.

For the log above, I parse the following:
Policy: Problem-Site
Payload: POST /tracker/update.jsp

I also log non-http denies as well, these appear like the following:
06/14/2010:21:08:03 ns PPE-0 : SSLVPN NONHTTP_RESOURCEACCESS_DENIED 69761 : Context wireless@ – SessionId: 5- User wireless – Client_ip – Nat_ip “Mapped Ip” – Vserver – Source – Destination – Total_bytes_send 291 – Total_bytes_recv 0 – Denied_by_policy “TOP-SECRET-DENY” – Group(s) “SCIF-NET USERS”

Here is a Scenario: You read a story in “” about some kid who tried to give a bunch of sensitive data to a hacker or even wiki leaks and you are concerned about your own data being accessed without authorization. You want to monitor all attempts to get unauthorized access and you want to note them, or, since they are in SQL Server w/reporting services, create a dashboard that goes RED when a particular policy is tripped.

Another scenario would be to actually monitor successes and note the “Context”, if most users who access data provided by the “TOP-SECRET-ALLOW” policy come from a specific network ID, say and you start seeing access from then you can see if a user ID has been compromised, you can also query and see how often a user accesses data from which IP Addresses. If someone’s account is compromised, it would show up as coming from another IP as it is less likely that they are sitting at the user’s terminal.

In the log above I parse the following:
Destination: (note the :139 indicating an attempt to use SMB)
Payload: (Blank if not HTTP)

Below is an example of Reporting Services dashboard that refreshes every minute:(Note, I have a particular Policy that turns red in this dashboard to alert me of an important breach attempt)

Time Appliance Context Destination Policy Payload
12:37 wireless@ :3389 TOP-SECRET-DENY  
12:37 wireless@ :3389 TOP-SECRET-DENY  
12:37 wireless@ TOP-SECRET-DENY  
12:37 wireless@ TOP-SECRET-DENY
12:37 wireless@ Problem-Site POST /tracker/update.jsp
12:37 wireless@ TOP-SECRET-DENY   


What You need:

  • You need an incumbent SQL Server Environment, you need Reporting Services if you want dashboards (If you have edgesight you should already have this)
  • You need to be able to set up an ODBC Connection, remember if it is a 64-bit server/workstation you need to use the ODBC tool in %Systemroot%\sysWOW64
  • You need to be able to set up a database connection in Reporting Services
  • $245 bucks for a full version of KIWI, if you buy a Netscaler you can afford a full version of KIWI, I will cover several solutions that will make this the best $245 you have ever spent.

How to set it up:
Once you brow beat your cheap boss into spending the $245 on KIWI you perform the following steps:

Go to and download all of the files. (Follow the instructions in the post)

Create a Database called Syslog with a username and password that has DBO privileges and create an ODBC Data Source on the server hosting KIWI for the syslog database and name it syslogd.

After renaming Netscaler.txt to Netscaler.ini go to KIWI and import the ini file.

On each rule, go to the “Write to SQL” Action and click “Create Table”

On each rule, go to the “Parse Data” Action and click “Browse” to upload the parsing script that goes with each rule. (Check all checkboxes under “Read and Write”

Once this is done you will be able to collect a ton of information that is very useful and it beats the hell out of a 90GB ASCII file or just writing everything into a single event correlation system without the ability to query on certain columns. All of the parsing scripts write the entire log to the msgtext column so you still have the original log if there is every any questions. Being able to parse key information in a specific column will give you a considerably higher level of agility when searching for information about a particular user, IP Address, destination or Security Policy.

If there is a worm that is sending a particular payload over http, you are one query away from finding out every infected IP Address. If an auditor asks you how many users have accessed a sensitive server you are a query away from providing that information. I will supplement this post with a video of the entire setup from start to finish on within the next two weeks (Hopefullly).

Also, I tried this in a home based lab (I cannot use my logs from work) so please, if you have any issues getting it to work, let me know so I can set up better instructions. And keep in mind, I have not looked at this with ICAPROXY logs, I am hoping to do that ASAP, there may be a supplement to this that includes a different script and maybe a different table for ICAPROXY logs. I am waiting on an enhancement request before I tackle ICAProxy logs (They will come across as “SSLVPN” but the log does look different than standard VPN logs).

And most importantly, I am not a Developer, I am a poor-man’s DBA and am a marginal scripter at best, if you can write a better parsing script please let me know!!

Thanks for reading

John Smith

The Digital SCIF: Compartmentalizing Sensitive data with Access Gateway Enterprise Edition (SCIFNET)


A little over six months ago Citrix released the Netscaler VPX virtual appliance and I was immediately thrilled with the potential to create my own virtual lab using XenServer and internal Xen networks on the hypervisor for downstream hosts. What I noticed was that I could locate resources inside a hypervisor’s black network and make them available externally via a VIP or a secure tunnel via a VPN connection. This lead me to believe that a resource that is, for all intents and purposes, off the public internal network can live safely on this network and never be exposed to the corporate network giving administrators another layer to further compartmentalized sensitive data off of an internal network. The compartmentalizing of sensitive data made me think of a military/DOD term called “skiff” or more appropriately Sensitive Compartmentalized Information Facility or a more appropriate acronym, SCIF. With a SCIF, all access, work and manipulation associated with specific sensitive information occurs within the confines of a specific building. What I am proposing is that you can use an Access Gateway Enterprise Edition to grant access to specific resources following this same model providing secure access, accountability and ensure that the only way to get to that data is via a gauntlet of two-factor authentication, application firewalls and endpoint analysis prior to the 2nd level of policy based access to internal resources that are only accessed via this secure tunnel.

SCIFNET: (“skiff-net”)

Placing a VPN in front of resources is not necessarily new, while VPN’s are most commonly used for remote access, there are instances where an administrator will use a VPN to secure a wireless network or to provide secure access to sensitive information. What I will describe in this is the next level where not only access is restricted but how the AGEE can integrate with the existing identity management framework as well as provide extensive logging and policy based access providing a least privileged model on a per resource basis.

Why put my data in a SCIF?

Currently your internal network is protected either by a NATed firewall, internal ACL’s etc. More mature networks have already layered their services by specific networks placing Oracle servers in one Network, Web Servers in another, SQL Servers in still another network, etc. As the security screws get tightened year after year we find that segmenting our services to particular networks may not be enough. Imagine if a database resided on a server that was completely invisible to the internal network that did not even have a default gateway assigned to it? No MAC Address to show up in ARP tables? No ports exposed via a NESSUS/SATAN/SARA scan?

In the “glass-half-empty” world of IT Security there are two types of systems, compromised and being-compromised. In 2004, during a particularly heated security discussion I suggested that the only way we could truly secure our systems was to unplug them from the network. With the SCIFNET solution I am proposing, you create an internal Network on your XenServer or ESX Server that does not reside on the internal network. This means that all communications occurs on the bus of the Hypervisor which has gigabit level speeds available on it.

So your SQL Server and Web Server are living inside a hypervisor with no Default Gateway and no ability to route to your internal Network? Great job…now how do you make it available? Well, in an earlier blog I discussed my time working as a County health inspector and when I inspected a convenient store in a particularly bad neighborhood, the shop owner would open a barred window and ask the customer what they wanted, he would take the money and go and get the merchandise and the entire transaction occurred outside his store. In this scenario, his exposure and risk was limited as the person was never allowed to enter the store and potentially rob him or attempt to leave with merchandise he/she did not pay for. SCIFNET works in a similar fashion where by the user connects to an Access Gateway who has a leg in both Networks but unlike a door, it is more like a barred window granting access to internal resources. But even better than my shop owner, I will log each access, I will account for how long they used the resource and I will log all un-authorized access attempts to this resource as well. By inserting a VPX in front of the resource, I am able to provide barred window access to sensitive resources that includes the highest level of accountability and record keeping.

Barred Window Access:

The Netscaler VPX provides for several secure access solutions to ensure anyone entering the secured network passes several forms of authentication, endpoint analysis and application firewall rules. Through each of these, before they even begin to attempt to access internal resources, they are met with a myriad of rules and scans to ensure they are allowed to even attempt access to sensitive data. While I may locate a resource on an internal Network on my hypervisor, I can offer it to the end user in a variety of ways among them via VPN or via AAA Authentication to a VIP. So while my web-server/db-server combo may exist on a completely invisible network inside a hypervisor, I am able to deliver it by creating a VIP on the VPX and offering that VIP to users on the internal Network. I can add a layer of security by forcing AAA Authentication to that VIP as of version 9.x of the Netscaler. If you need to grant non http access to a server that has either sensitive documents or a back end database you can offer a VPN tunnel into the internal network on the hypervisor. With split tunnel turned off, you can ensure that the client is only able to access internal resources while connected to the VPN and keep any outside connections from getting in.


As with the hardware appliance, the VPX allows for two factor authentication using smart cards(HSPD-12), SecurID, LDAP(AD/NDS/eDirectory) and local Authentication. All AAA logs can be sent to an event correlation engine for parsing and accountability to ensure that access attempts are accounted for and breach attempts can be reported and acted on immediately(Custom solution, email me if you are interested in it). Currently, I tested two factor authentication with AD Credentials and SecurID tokens and have used Smart Cards (CAC) Cards in a single authentication mode without any issues.

Endpoint Analysis:

In addition to authenticating users who wish to access sensitive data, you can also set minimum standards of the systems accessing the data. Using the VPX, you can ensure that systems accessing the SCIF have adequate virus signatures, host based firewalls and encryption software. Using Endpoint Analysis, you can ensure that any system meets a pre-selected set of requirements prior to accessing the systems inside. This will ensure that an infected system or a system that possesses an outdated virus signature is not allowed access. You may also only want a select group of systems accessing the SCIF, by putting a watermark in the registry. By scanning for this specific watermark, you can further restrict the number of systems that are allowed access in addition to the number of users.

Application Firewall:

Not everyone purchases this feature, in fact Citrix does not bundle this with the Express edition of the VPX but you can get a 90 day platinum edition that has it. What the application firewall does is allow your front end SSL VPN solution to be protected by a layer 4-7 firewall. By enforcing a “START URL” rule you can ensure that anyone who attempts to access the system by IP is dropped meaning any worm that is on the loose or person looking for port 443 or port 80 over an IP will not be able to access the authentication page. This same solution provides for Buffer Overflow, SQL Injection, Cross-Site Scripting and Custom based URL filter protection. An individual would need to know the exact URL to connect to before they even get a chance to Authenticate and be scanned.

Accessing Sensitive Resources:


Okay, you have typed in the correct URL, you have all of the necessary virus updates and watermarks to pass endpoint analysis and you have passed the two factor authentication, now you are free to access whatever you want inside the SCIF correct? No, in fact you have only entered the building, now the actual compartmentalized access control begins to take shape. While most SSL VPN Solutions will offer a similar gauntlet to logging in, once you are in the door, you can attempt to get to any IP address thereafter. The 2nd part of this posting has to do with what can be done after you have authenticated to ensure a user just doesn’t wander around the network looking for vulnerable systems. There are 3 parts to setting this up, Active Directory groups, Authorization Policies and the resources themselves.


Resources are defined by IP Address, Network ID and Port. For example, we have a database server that we want to allow a non-web based front end application to connect to. You create an internal Network on the XenServer where you want that resource to go than place the Virtual Machine on the XenServer and assign it to that network. The resource is accessed via the VPX who has a leg in both networks and bridges you from your internal network to the resource. Resources are defined to the AGEE via the Authorization Policy as an IP Address, Network and port. So my SQL Server that I have placed in (Already configured) with an IP Address of will be the resource I grant access to.

Authorization Policies:

This is the hierarchy for setting up access, AD Groups are assigned Authorization policies and Authorization policies have resources instantiated as rules. Using the resource above I would create an Authorization policy called “Sensitive DB” and assign the network ID or IP Address and port to that specific policy. You can assign more than one resource to an authorization policy. Once this is done, you can assign the policy to a group which brings us to the Active Directory integration with the AGEE.

Active Directory Group Extraction:

On the AGEE you will create a group that matches, exactly, the name of the group in Active Directory. This process is LDAP extraction so the same should work for eDirectory/NDS, iPlanet/SunOne and openLDAP. So let’s say for the example above we create an AD Group called “SensativeDB”. I create that exact same group on the Netscaler and so log as the user authenticates via Active Directory, the AGEE will check for matching LDAP groups. By assigning an Authorization Policy to a specific group, you can ensure that your access control to the sensitive information is still managed by the incumbent identity management framework and you also ensure that only users in specific groups are given access to sensitive data. The AGEE will act as the doorman ensuring that no one gets access to any area’s they are not supposed to.

Can I add access to resources outside of the SCIF?

Yes, if an outside resource on a different network needed to be made available to you while you were working inside the SCIF than you could accomplish this using the AGEE by setting up a VIP. If you were connected via VPN to the SCIF network (say and there was some reference data located on another network than you could create a VIP on the network and present external data to the inside with the same security gauntlet that you would present VIP’s to the internal Network. Say you had a group of contractors that you wanted to restrict to a SCIFNET but they also needed access to a web-based time keeping application, you could create an internal VIP and present it to the users inside the SCIF without exposing the entire internal network.

Integrating SCIFNET with VDI:

Initially, I wanted a similar situation as with a SCIF where a person walks into a room and accesses a secure terminal and from there you can access sensitive data on a network. In this manor, I can ensure that the end user is accessing data from what amounts to a glorified dumb terminal. Placing the VDI environment inside the SCIF created some federated services challenges that I have not mastered yet. Namely, you need AD to use XenDesktop and this meant poking a hole to allow for that AD integration. Also, with Endpoint Analysis and the “Barred Window” access offered by AGEE I felt the risk was mitigated. With Split Tunneling off and only allowing VPN traffic once the user connects to the AGEE I felt like we would be pretty safe. Also, you can still use VDI just one on your incumbent internal network instead of inside the SCIF. Otherwise, you need to set up a completely new AD Infrastructure inside the SCIF. I am not well versed enough with ADFS or some of the solutions to be able to adequately address this in this paper.

Can this be done without using a black network or VM’s:

It is likely more experienced readers have already made the connection to this and realized that yes it can be done. For Federal Government Sites, I would recommend putting a Netscaler 9010 with a FIPS module on the Network than set up an entire switched network that is NOT on the internal network but bridged by the AGEE software on the Netscaler. You can still deliver “barred window” access to the physical resources and you do not have the risk of the hypervisor itself becoming compromised. In production, it may be a lot harder to get the VPX based solution approved by security personnel but physically segmenting your resources may be easier to get approved and while I have not seen it in my environment I am quite sure a similar solution currently exists using either PIX or IOS based ACL’s.

Logging and Accountability:

What I like the most about using the AGEE for compartmentalized access is the logging. While a PIX or IOS based ACL will give you an offending IP. Currently, my VPN logs, once parsed and written to SQL, have the userID in addition to the port, source and destination IP Address. This means that I can type the IP Address of a resource into my SQL Reporting Services website and get the date, time, external IP, port and username of every single user who has accessed that resource. Additionally, the AGEE logs policy hits weather they are ALLOWED or DENIED. Once finished parsing, I can, on an hourly, daily or monthly basis check for users who trip the “DENIED” policy. Since I already have the username in my logs, I don’t have to hunt down who had what IP Address. This places me in a position to be more proactive, if I see a large number of ACCESS DENIED logs, I can go in and immediately kill a user’s VPN Session post haste. This also provides the opportunity to log access by user ID. The Digital Epidemiology portion is a whitepaper itself but having a user ID tied to each log makes incident response much faster.


You have a key resource at that must have a blanket “Deny” applied to it and is only available via exclusive “Allows”. For this you can create an Authorization policy called “TopSecret” and you create a rule for DESTIP== with an Action of DENY. You bind this policy to your AD Group and you set it higher than any other policy. This will ensure that if they attempt to get to that server, they will be denied access. What I like about the AGEE logs is that I get a username and the policy that was violated as well as the sourced IP Address. Effective parsing of these log files will allow for you to use event correlation to find out who has attempted to make unauthorized access.

 Example Log file from blocked access:

15:16:39     01/03/2010:20:15:40 GMT ns PPE-0 : SSLVPN NONHTTP_RESOURCEACCESS_DENIED 1250215 : Context jsmith@ – SessionId: 15- User jsmith – Client_ip – Nat_ip “Mapped Ip” – Vserver – Source – Destination – Total_bytes_send 298 – Total_bytes_recv 0 – Denied_by_policy “TopSecret” – Group(s) “CITGO VPN Testers”

While many segmented networks will have PIX logs that will give you this information, what I like about these logs is that I can parse them into a database and put each item marked red into a column for date/time, action, context, policy so in my database a query would return the following:

Time Context Destination Policy Action


jsmith@ TopSecret DENIED


In this scenario, I can immediately ask jsmith why he/she is trying to access this system. I have a record of the breach attempt and can even configure KIWI to alert me via Email at the exact time the breach occurs.

Likewise, with the AGEE I have a record of the successful attempts as well.

17:13:10    01/03/2010:22:12:10 GMT ns PPE-0 : SSLVPN TCPCONNSTAT 1299232 : Context jsmith@ – SessionId: 16- User jsmith – Client_ip – Nat_ip – Vserver – Source – Destination – Start_time “01/03/2010:22:12:10 GMT” – End_time “01/03/2010:22:12:10 GMT” – Duration 00:00:00 – Total_bytes_send 48 – Total_bytes_recv 19 – Total_compressedbytes_send 63 – Total_compressedbytes_recv 39 – Compression_ratio_send 0.00% – Compression_ratio_recv 0.00% – Access Allowed – Group(s) “CITGO VPN Testers”

Note that you do not get a policy named with the log, however all Deny’s should have the policy that denied them.


I plan to include some videos on how to accomplish this, it is relatively simple. This is also not a new concept and networks use IOS based ACL’s to accomplish this but I believe the AGEE be it as a Virtual appliance or physical hardware, provides a much easier solution than an enterprise NAC endeavor. In fact, I have heard some horror stories regarding NAC deployments. In the interim, while NAC continues to mature and organizations ease into their NAC solutions, SCIFNet allows you to perform the same security levels without taunting specter of an enterprise NAC deployment. Compartmentalize sensitive data and place an AGEE in front of it and you have all of the same benefits of Network Access Control at a fraction of the price and overhead.

 To see a video of SCIFNET put to use with a VPX and an internal XenServer Network click here:

Thanks for reading