I was reading this description about how Kerberos works.
I am a bit puzzled by this part:
Why are we sending the lifetime of the Ticket for the HTTP service in plaintext?
That would mean that anyone with access to the network can find out what services we are using and for how much time. That doesn't sound like great privacy.
The description you read is wrong. There is no plaintext lifetime in the initial Kerberos packet request from the client to the KDC TGT service - just a request for a service ticket. The service ticket coming back containing the lifetime is encrypted. One won't see the details of that in plain text over the wire. These details explained in RFC 1510 and 4120. Note: If you run klist on one of the endpoints - client, KDC, or server you will see Kerberos ticket lifetimes in plaintext - but that is different - you are already on the host and using a specific tool to do so.
Related
I’ve written an OPC UA Client and i’m using ProSys OPC UA Simulator Server to test it. Running in Anonymous mode my client connects and i can browse the server. however when I configure my client to use a Username and Password it fails with No Suitable UserTokenPolicy found for the possible endPoints. I’ve debugged it and it appears that http://opcfoundation.org/UA/Se…..olicy#None is not in the endpoints userIdentityTokens array, although in ProSys it states it is.
I’ve set up a user in The OPC UA Simulator Username & Passord box is ticked
Security Modes = None
Security Policies = None are ticked
The list of server EndPoints
Security Mode = None
Security Policy = None
So i would expect to see it in userIdentityTokens array.
My Client is written using the Open62541 libraries
Any help would be appreciated.
Thanks
I haven't used the Open62541 libraries, but it seems the standard allows the OPC server to require that the username and password are encrypted even when the rest of the transport is not signed or encrypted.
It appears that at some point in time (and maybe still), Open62541 doesn't handle encrypting the password. Here are a couple of related github issues:
https://github.com/open62541/open62541/issues/934
https://github.com/open62541/open62541/issues/1548
https://github.com/open62541/open62541/issues/2757
I am working on a node.js OPC UA client based on the node-opcua library, and I was able to verify that I can connect to the ProSys OPC-UA simulation server with the security mode set to none and user authentication set to username & password. I do not know what type of password encryption node-opcua is doing behind the scenes, but it works.
----- Additional info -------
I found another forum with some clarification: https://forum.prosysopc.com/forum/opc-ua/clarification-on-opensecurechannel-messages-and-x509identitytoken-specifications/
The key part:
If passwords are sent, they will be encrypted as defined by the
UserTokenPolicy (which is separate from SecurityPolicy, but similar).
The Application Instance Certificates will be used for the encryption
in this case – and therefore they are required to be exchanged even
when MessageSecurityMode=None.
I have deployed liberty app on IBM cloud. I have setup custom domain and selected "request client certificate" so that clients have to send certificate to access app over TLS. I see client authentication does work, but I do not get any client certificate information in my app. This makes client certificate authentication a bit useless, as I would want to know the id of client which accessed my app. Any help/pointers appreciated.
I looked at attributes of request. Two attributes are passed in request _com.ibm.websphere.servlet.uri_non_decoded_ with value /dummyRelPath and _javax.servlet.request.cipher_suite_ with value of ECDHE-RSA-AES256-GCM-SHA384 There's no attribute with name javax.servlet.request.X509Certificate passed in request.
Does:
X509Certificate[] certs = (X509Certificate[])
request.getAttribute("javax.servlet.request.X509Certificate");`
not return any certificates?
In cloud foundry on bluemix, your client should be handshaking with a DataPower proxy. That proxy adds a custom header to indicate the TLS client cert that was provided, then it is passed through the CF gorouter, then finally passed to the JVM.
WebSphere Liberty then surfaces that through the API above.
This is communicated through the $WSCC request header. If the API returns null, it's most likely that header was dropped or never set by the infrastructure, rather than making it all the way there and the API mysteriously losing track of it. You could dump the request headers, looking for this one in particular, and maybe something will stand out (some surprise hop/proxy).
Does kerberos encrypt only the authentication process or all client communications?
I was under the impression it was like a VPN for the LAN.
So that all LAN communications are encrypted. Just like all internet communications are encrypted with a VPN.
Regards
Aubrey
Kerberos is quite capable of encrypting traffic between client and server, but depending on exactly how kerberos is used in the application, it may or may not be using the kerberos session keys to encrypt the traffic.
The kerberos protocol provides the means to exchange a session key that can be used to encrypt message traffic after the initial authentication exchange. Encrypted message exchange is generally the default for protocols that actually use GSSAPI. See gss_wrap documentation
GSSAPI is a generalized API for doing secure network applications. Kerberos is the mostly commonly used driver underneath GSSAPI.
If the application does not use GSSAPI, or the native kerberos messaging libraries, then it is likely using TLS to encrypt the traffic or the traffic is not encrypted.
Kerberos message encryption was designed to support relatively long lived tcp based client/server applications ( think telnet or ssh ). The API does not always map well to the way current applications are architected. Kerberos support is often bolted on well after the application is under construction
and is only used for authentication.
Kerberos is an distributed service that is generally used for secure authentication only. It does neither ensure that a user has the required permissions to access a resource (that would be Authorization) however it may be used to encrypt arbitrary data. As per RFC 3961 "Encryption and Checksum Specifications" which extends and correct aspects of RFC 1510 the Kerberos protocol provides confidentiality and integrity services.
While Kerberos can be used to encrypt information passed between authenticated peers in many cases it only performs the authentication step. Thus, you will find that Kerberos is used as component in a secure environment to ensure a secure authentication with other components and protocols handling the authorization and the secure transport.
In the end, it heavily depends on your usa-case to determine if the tradeoffs between using Kerberos or something else as a transport protocol make sense for you.
While the Kerberos protocol can be used to provide encryption services on most platforms, microsoft provides no mechanism to do this directory. Instead GSSAPI may be used to call these services.
For example, Active Directory uses Kerberos for message integrity.
Similarly, you could use e.g. TLS or IPsec to encrypt your data on the wire and combine it with Kerberos for authentication. But again, this is another protocol performing the actual transport encryption and just using Kerberos as an authentication component.
As I understand it,
SPN is an authenticating tool for windows services.
Kerberos is a
user authentication service
SPNEGO-GSSAPI is the third party API to
be able to use those services.
SSPI : is the Neutral layer to send
request from SPNEGO to SPN service.
Am I completely lost?
Trying to figure out how it works but information, is either too precise or not enough.
Ok a more verbose answer:-
SPN - Service Principal Name. It is an identifier associated with each account in a KDC implementation(AD, OpenLDAP etc). Basically if your account acts as a service to which a client authenticates, the client has to specify "who" it wants to communicate to. This "who" identifier is the SPN. This is the strict definition. Many people often call the client name (UPN - User Principal Name) of a service as SPN. This happens when the service itself may act as a client( google the delegation scenario ). This is not strictly correct but widely assumed true.
Kerberos is a protocol for authentication. It is a name for a framework. It involves a third party server(called KDC or Key Distribution Centre) and involves a series of steps of acquiring tickets(tokens of authentication). It is really complicated so http://en.wikipedia.org/wiki/Kerberos_(protocol)
To some extent you got this right. GSSAPI is an API but SPNEGO is not. GSSAPI is technically agnostic to the auth mechanism you use, but most folks use it for kerberos authentication. SPNEGO is a pseudo mechanism, in the sense it declares an RFC for authentication based communication in HTTP domain. Strictly speaking SPNEGO is a specification but most folks also consider it as an implementation. For instance, Sun and IBM JDK provides "mechanism providers" for SPNEGO token generation but GSSAPI is used to actually call it. This is done in many projects(Tomcat as a Server is and example that come to the top of my head and one of the folks who answered this question developed it).
SSPI is an analogue to GSSAPI in windows. Its a different API which ends up doing something very similar to GSSAPI.
Not quite.
SPN simply means 'Server Principal Name' and is the AD or Kerberos slang for the service you try to authenticate against.
Kerberos is a user authentication service, more or less yes. It also provides security for network messages and calls between services.
SPNEGO-GSSAPI* is a kind of strange beast. GSSAPI (Generic Security Service Application Program Interface) is an API to (in principle) different authentication services, it provides negotiation of the mechanisms used. Often the only mechanism available will be Kerberos though. It is the usual API to attach 3rd party programs to Kerberos when you are on Unix (defined in various RFCs, for example RFC 2743 )
On the windows platform SSPI is the generic layer, so it compares to GSSAPI.
SPNEGO is kind of a strange hybrid. It is a mechanism to be used in SSPI, HTTP Auth or GSSAPI which negotiates another auth protocol (for example Kerberos or NTLM if you are on Windows), so it basically does the same thing GSSAPI does again in a different way.
Typical uses of SPNEGO are HTTP authentication to a windows domain, for example IIS uses it if you use 'Integrated windows authentication'. It is also used when you select the 'Negotiate' options for SSPI. See for example RFC 4559
Almost all of your understandings are wrong.
Here it goes:
SPN: A specific service-class is bound to a specific account, e.g. HTTP to www.stackoverflow.com => HTTP/www.stackoverflow.com#STACKOVERFLOW.COM
Yes
3./4. GSS-API (Unix)/SSPI (Windows): Mechanism neutral API to interact with. E.g, Kerberos 5, NTLM, SPNEGO, etc.
SPNEGO: It is one of many mechnisms supported by GSS-API/SSPI. It is actually a pseudo-mech.
I need to setup a cron job to run a SOAP client. The customer insists that I connect to their web service (on an https address) from an https address. They insist that if I don't their response to me can't be encrypted.
My first question is, is that true? I thought that as long as I'm connecting to their SOAP service over https, the response back would automatically be encrypted.
If that's true, how can I run a cron job to be as https? My site is on a LAMP setup with cPanel access.
Thank you in advance for your help!
Your customers statement seems to be a little bit unclear in what he/she specifically means by "... connecting from an https adress" as there isn't any notion of the term "https adress" in the specs and https URLS only seem to make sense in the context of Request-URI s given in a https request.
Given this unclarity I'm only wild guessing. Nevertheless to me it seems your clients requirements might most probably not be connected to the http protocol but rather to establishing your TLS connection.
If your client is very sensitive in respect to the security of his system - which in fact if he intends to offer RPC requests might be a very good idea - he might not want to the whole world to be able to connect an encrypted connection to his machines and rely on any secondary authentication mechanism once the connection has been established.
As most users of the public internet don't have any certificates signed by a trusted authority this feature it isn't used out in the open wild but besides server authentication the TLS handshake protocol also provides a means of client authentication via client certificates (the relevant part being section 7 in RFC 5246 here. see: https://www.rfc-editor.org/rfc/rfc5246#section-7)
While in the absence of widely used client certificates web services usually rely on establishing an encryted connection to first to authenticate users by some kind of challange response test like querying for username and password your client might want to either additionally secure access to his machines by additionally requiring a valid client certificate or even - probably not the best idea - replace a second authorization like the one already mentioned above.
Nevertheless all this are nothing but some ideas that I came along with given the riddle in your question.
Most probably the best idea might be to just ask your client what he/she meant when saying "... connecting from an https adress"