Subject: [Netconf] Netconf Notification: One last bit of Discuss: Session Accumulation

From: "Sharon Chisholm" <[email-masked]>
Date: Mon, 16 Jun 2008 07:52:51 -0400

Hi

I originally thought this would not require an update to the document,
but here it is. I propose the following text to resolve:

If a malicious or buggy NETCONF client sends a number of
<create-subscription> requests  without ever terminating any of them,
they will accumulate subscriptions and begin to use up system resources.
They do so while accumulating NETCONF sessions and when the underlying
NETCONF session is terminated, so is the Notification subscription. The
<kill-session> operation should be used to terminate any suspect NETCONF
sessions.

>There is only one remaining issue.  I identified tha following issue
from Blake Ramsdell's >secdir review as blocking:
>>
>>
>>> * Is there a risk of sessions accumulating? That is, too many
>>>   create-subscription requests without termination?
>>>
>>
>
> From the authors explanation, it is the netconf server's
responsibility to kill sessions if needed to address a DoS attack.
>
>> The subscription terminates when the underlying NETCONF session goes 
>> way. In order to accumulate subscriptions, you need to accumulate 
>> NETCONF sessions. These may well be a finite resource, but the base 
>> protocol provides a <kill-session> command to kill a particular 
>> session from another session if there is an issue.
>>
>
>The explanation is fine, but I think a sentence or two in the security
considerations is needed to alert implementers.  I believe this can be
easily resolved with an RFC Editor Note.

Sharon Chisholm
Nortel 
Ottawa, Ontario
Canada
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