Archive

Archive for November, 2011

Certificate validation problems after upgrading to Tortoise 1.7

November 28th, 2011 No comments

A few days ago while starting TortoiseSVN it prompted me to update to version 1.7

After I updated to version 1.7. I could not connect to our internal repository anymore. The connection failed with the following error: SSL error: sslv3 alert certificate unkown.

SSL error: sslv3 alert certificate unknown

SSL error: sslv3 alert certificate unknown

Our internal respoitory is secured with a certificated issued by our internal CA infrastructure.

Root CA

|
v

Intermediate Certificate

|
v

Repository certificate

Surfing to the svn repository does not produce an error, so the certificate chain is fine. At first I figured that Tortoise was using its own certificate store, but it turns out that Tortoise does use the Windows Root CA store, so there is no need to add the Root CA.

After some more investigation we found out that Tortoise does use the Windows Root CA store to validate the certificate chain, but does not use the Intermediate CA store to complete the certificate chain, like windows does. Since all our client machines have the intermediate certificate in the Intermediate CA store we never noticed that the certificates offered by apache were not chained. After chaining the repository certificate with the intermediate certificate Tortoise was able to talk to the repository again.

Page load performance with a Cisco ACE4710

November 16th, 2011 No comments

The ACE has two different ways of treating the L7 connections internally, that we call “proxied” and “unproxied”. In essence, the proxied mode means that the traffic will be processed by one of the CPU (normally to inspect/modify the L7 data), while, on the unproxied mode, the ACE sets up a hardware shortcut (Fastpath) that allows forwarding traffic without the need to do any processing on it.

For a L7 connection, the ACE will proxy it at the beginning, and, once all the L7 processing has been done it will unproxy the connection to save resources until L7 processing is required again. Before it goes ahead with the unproxying, it needs to see the ACK for the last L7 data sent.
In packet captures, we see that the client is taking approximately 200ms to send this acknowledgement each time. When a connection is composed of many HTTP requests, the proxy/unproxy process can add up a total delay of several seconds.

The configuration of a sorry/backup server farm with for example a HTTP redirect to a sorry page will cause the ACE to treat the connections to the VIP as a L7 and influence the total page load time.

The proxy/unproxy delay can have a big impact for situations in which the client is taking a long time to send the acknowledgement, so, the ACE allows to change the behavior. It is possible to define a “round-trip-time” threshold so that connections from clients with a RTT value higher than the threshold are never unproxied.
You can do this by setting the threshold to 0 to ensure to keep connections always proxied. To do this, you would need to configure a parameter map like the one below and add it to the policy-map.
parameter-map type connection
set tcp wan-optimization rtt 0

Even though this setting will most likely solve the issue, it also has some drawbacks. The main one is that the ACE appliance only supports up to 256K simultaneous L7 connections in proxied state (which includes also the connections towards the servers, so, it would be 128K for client connections), so, if the amount of simultaneous connections reaches that limit, new connections would be dropped. The second issue, although not so impacting, would be that the maximum number of connections per second supported would also go down slightly due to the increased processing needed.

Categories: Cisco Tags:

Online DNSSEC verification

November 16th, 2011 No comments
Categories: Technology Tags:

Cloud security considerations

November 3rd, 2011 2 comments

There are many concerns these days on security when taking services from cloud providers. All the areas where Schuberg Philis is actively being audited on, are area’s of concerns for IT managers.

How do I know my cloud service is being hacked and abused if it is not running inside my datacenter? What possibilities do I have to check if my employees are acting along the lines of my Acceptable Use policy? Where are the logs of that abuse, and how can I trust the logs? How do I know that my data is not copied elsewhere in the cloud, and analysed offline by my competitor?

With regards to cloud storage, the CDMI (Cloud Data Management Interface) is trying to address some of the questions, but is only one step forward.

Cloud service providers still have a long way to go. An initiative like Eurocloud  is doing great work in paving the road to trust in cloud service providers.

When cloud service providers will be able to succesfully address the concerns, they have a big advantage over the classical IT model of running your own IT: they provide all the securities you would normally build and control youself, but combined with cloud advantages like fast provisioning and fast reuse of resources.

Small and medium-sized business will then be able to actually get a better and more secure service with cloud services, then what they could build and control themselves.

What does this mean for SBP? Sure there will be competition from the cloud providers. But we are nothing more than just another cloud provider. We build services for our clients with our own cloud technologies of fast provisioning, centralized log analysis, but since we build private clouds for our customers, these customers can demand tailored solutions to address their specific needs and concerns.

Cloud computing is not a threath to our business model, but is preparing the market more and more for putting commodity services in the big generic clouds, combined with the need of supporting highly tailored private clouds.

So it is time to face the fact: Schuberg Philis, the private cloud company!

SNW europe, powering the cloud

November 2nd, 2011 No comments

Powering the cloud. Multi marketing of course, but what is happening in the storage world? What does it mean for mission critical environments? These are the questions I am hoping to get answered today and tomorrow. Currently three sessions done. 1. Introduction to Data protection by Chriss Sop, 2. Optimizing storage in a cloudy, virtualized world by The 451 Group and 3. Enterprise Tiered Storage by John Locky.

First two sessions were somewhat low quality from a contect perspective. Too basic from on technology and on new innovations. Even for me as a non engineer. The difference between full backup, incrementals and differentials is not the thing we came here for. Although i must say that merging incrementals on the back end to always have full backups available sounds interesting. Curious to see this working in real life. How transprrent will that be? Lets ask Commvault later today. And if i can find them Quest as well. Would be nice to learn a bit on automated restore testing as well. Guaranteeing back ups remains an issue. Especially on tapes.

When i get answers, you’ll probably read more about it on cf.net or twitter.

F5 BigIP LTM IPv6 RA

November 2nd, 2011 No comments

In order to have the F5 BigIP LTM announce IPv6 Router Advertisements (RA) you have to logon to the console and create the following config file:

#
# /etc/radvd.conf
#
interface [interface name]
{
AdvSendAdvert on;
MinRtrAdvInterval 5;
MaxRtrAdvInterval 10;
AdvDefaultPreference low;
AdvHomeAgentFlag off;
prefix xxxx:xxxx:xxxx::/yy
{
AdvOnLink on;
AdvAutonomous on;
AdvRouterAddr off;
};
};

You have to use lower-case characters for the interface or vlan name otherwise this will not work!

Then stop the service: bigstart stop radvd
And start the service again: bigstart start radvd

Categories: F5, IPV6 Tags: