[Spread-users] Re: Using spread in secure group communication

Thu Feb 16 02:06:08 EST 2006

John,

Thank you for your quick reply. Due to your hint on the broadcast 
address, I was able to resolve the problem in the config file. It was 
due to the fact that the broadcast address on the spread segment was 
still at 127.0.0.255, instead of the 1.2.1.255 value it should be for 
our test network.

We will look forward to the new version of Spread! Will there be any 
significant changes in the API? In other words, would you recommend we 
hold off coding with Spread's current API for a short time?

Thank you,
Adam

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> Today's Topics:
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>    1. Using spread in secure group communication (Adam Lamar)
>    2. Re: Using spread in secure group communication (John Schultz)
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> ----------------------------------------------------------------------
>
> Message: 1
> Date: Mon, 13 Feb 2006 16:24:10 -0800
> From: Adam Lamar <adam at uidaho.edu>
> Subject: [Spread-users] Using spread in secure group communication
> To: spread-users at lists.spread.org
> Message-ID: <43F1232A.5030500 at uidaho.edu>
> Content-Type: text/plain; format=flowed; charset=ISO-8859-1
>
> Hello,
>
> We are considering using spread for a secure group communication 
> application. Spread seems to be the perfect fit, however, we are having 
> trouble getting spread to work exactly as we understand it does.
>
> We are testing spread on four machines on our local network. Each 
> machine has the spread daemon running and can communicate directly with 
> every other machine. We have defined our spread segment in the 
> spread.conf file with a listing of each machine name and IP address. 
> Communication is working with the spuser program in the client/server 
> architecture, i.e. if machines A,B,C,D connect to machine A's spread 
> daemon, each of the machines is able to join the group and send/receive 
> messages.
>
> The problem arises when we try to use spread in a distributed nature. If 
> each machine is running the spread daemon, it is our understanding that 
> machine A can connect to B, B can connect to C, and A will be able to 
> communicate with C through B. However, when we tried doing this with the 
> spuser program, this communication does not occur. In fact, watching the 
> packet dump does not reveal that any communication whatsoever is 
> occuring between the spread daemons. Is there something obvious that we 
> are doing wrong?
>
> Also, as we plan on using spread for dynamic groups, is is possible to 
> define (or for spread to automatically find) where each spread daemon is 
> located without restarting the spread daemon each time a new participant 
> joins the network?
>
> Thank you,
> Adam Lamar
>
>
>
> ------------------------------
>
> Message: 2
> Date: Mon, 13 Feb 2006 19:44:31 -0500 (EST)
> From: John Schultz <jschultz at commedia.cnds.jhu.edu>
> Subject: Re: [Spread-users] Using spread in secure group communication
> To: spread-users at lists.spread.org
> Message-ID: <Pine.LNX.4.62.0602131936300.31669 at commedia.cnds.jhu.edu>
> Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed
>
> Hi Adam,
>
> The first thing to do is to let us see the actual configuration file that 
> you are using.  Usually problems like this are related to simple 
> configuration errors.
>
> Your understanding of Spread's communication is *mostly* correct. 
> However, within a segment it is understood that when a daemon does a 
> hardware multicast that all the other daemons in the segment will have a 
> non-zero (actually quite high) chance of hearing the multicast.  That is 
> in fact the exact definition of a network segment in Spread.  So within a 
> segment it is generally assumed that you have full connectivity between 
> all the daemons there.  When this isn't the case, Spread will sometimes 
> have trouble functioning or be forced to do extra work in pathological 
> manner (e.g. - always recovering msg "losses").
>
> The fact that none of your daemons are perceiving each other hints to me 
> that you either have a configuration problem or a bad network setup (e.g. 
> - no multicast or broadcast).
>
> As to your question on dynamic reconfiguration of Spread daemons, the new 
> version of Spread, which will be going into public beta *very* soon has 
> added exactly that feature.
>
> Cheers!
>
> ---
> John Schultz
> Spread Concepts
> Phn: 443 838 2200
>
> On Mon, 13 Feb 2006, Adam Lamar wrote:
>
>   
>> Hello,
>>
>> We are considering using spread for a secure group communication application. 
>> Spread seems to be the perfect fit, however, we are having trouble getting 
>> spread to work exactly as we understand it does.
>>
>> We are testing spread on four machines on our local network. Each machine has 
>> the spread daemon running and can communicate directly with every other 
>> machine. We have defined our spread segment in the spread.conf file with a 
>> listing of each machine name and IP address. Communication is working with 
>> the spuser program in the client/server architecture, i.e. if machines 
>> A,B,C,D connect to machine A's spread daemon, each of the machines is able to 
>> join the group and send/receive messages.
>>
>> The problem arises when we try to use spread in a distributed nature. If each 
>> machine is running the spread daemon, it is our understanding that machine A 
>> can connect to B, B can connect to C, and A will be able to communicate with 
>> C through B. However, when we tried doing this with the spuser program, this 
>> communication does not occur. In fact, watching the packet dump does not 
>> reveal that any communication whatsoever is occuring between the spread 
>> daemons. Is there something obvious that we are doing wrong?
>>
>> Also, as we plan on using spread for dynamic groups, is is possible to define 
>> (or for spread to automatically find) where each spread daemon is located 
>> without restarting the spread daemon each time a new participant joins the 
>> network?
>>
>> Thank you,
>> Adam Lamar
>>
>> _______________________________________________
>> Spread-users mailing list
>> Spread-users at lists.spread.org
>> http://lists.spread.org/mailman/listinfo/spread-users
>>
>>     
>
>
>
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