Thread: [HACKERS] RADIUS fallback servers

I've given an initial review of this patch. It applies cleanly and
compiles without issue as of 6da9759.  I'm going to continue with
testing it against a set of RADIUS servers in the next few days. But
in the meantime, I have a few questions (below).

> It supports multiple RADIUS servers. For all other parameters (secret, port,
> identifier) one can specify either the exact same number of entries, in
> which case each server gets it's own, or exactly one entry in which case
> that entry will apply to all servers. (Or zero entries for everything except
> secret, which will make it the default).

I wonder if removing the complexity of maintaining two separate lists
for the server and port would be a better/less complex approach.  For
instance, why not go with a list of typical 'host:port' strings for
'radiusservers'?  If no port is specified, then simply use the default
for that specific host. Therefore, we would not have to worry about
keeping the two lists in sync. Thoughts?

> Each server is tried in order. If it responds positive, auth is OK. If it
> responds negative, auth is rejected. If it does not respond at all, we move
> on to the next one.
>
> I'm wondering if in doing this we should also make the RADIUS timeout a
> configurable as HBA option, since it might become more important now?

Yes, I think this would make sense and would be a good idea.

-Adam

I've given an initial review of this patch. It applies cleanly and
compiles without issue as of 6da9759.  I'm going to continue with
testing it against a set of RADIUS servers in the next few days. But
in the meantime, I have a few questions (below).

> It supports multiple RADIUS servers. For all other parameters (secret, port,
> identifier) one can specify either the exact same number of entries, in
> which case each server gets it's own, or exactly one entry in which case
> that entry will apply to all servers. (Or zero entries for everything except
> secret, which will make it the default).

I wonder if removing the complexity of maintaining two separate lists
for the server and port would be a better/less complex approach.  For
instance, why not go with a list of typical 'host:port' strings for
'radiusservers'?  If no port is specified, then simply use the default
for that specific host. Therefore, we would not have to worry about
keeping the two lists in sync. Thoughts?

> Each server is tried in order. If it responds positive, auth is OK. If it
> responds negative, auth is rejected. If it does not respond at all, we move
> on to the next one.
>
> I'm wondering if in doing this we should also make the RADIUS timeout a
> configurable as HBA option, since it might become more important now?

Yes, I think this would make sense and would be a good idea.

>> I wonder if removing the complexity of maintaining two separate lists
>> for the server and port would be a better/less complex approach.  For
>> instance, why not go with a list of typical 'host:port' strings for
>> 'radiusservers'?  If no port is specified, then simply use the default
>> for that specific host. Therefore, we would not have to worry about
>> keeping the two lists in sync. Thoughts?
>
>
> If we do that we should do it for all the parameters, no? So not just
> host:port, but something like host:port:secret:identifier? Mixing the two
> ways of doing it would be quite confusing I think.
>
> And I wonder if that format wouldn't get even more confusing if you for
> example want to use default ports, but non-default secrets.

Yes, I agree. Such a format would be more confusing and I certainly
wouldn't be in favor of it.

> I can see how it would probably be easier in some of the simple cases, but I
> wonder if it wouldn't make it worse in a lot of other cases.

Ultimately, I think that it would be better off in a separate
configuration file. Something to the effect of each line representing
a server, something like:

'<server> <port> <secret> <identifier>'

With 'radiusservers' simply being the path to that file and
'radiusserver', etc. would remain as is. Where only one or the other
could be provided, but not both. Though, that's perhaps would be
beyond the scope of this patch.

At any rate, I'm going to continue moving forward with testing this patch as is.

-Adam

On Mon, Mar 6, 2017 at 10:24 AM, Adam Brightwell
<adam.brightwell@crunchydata.com> wrote:
>>> I wonder if removing the complexity of maintaining two separate lists
>>> for the server and port would be a better/less complex approach.  For
>>> instance, why not go with a list of typical 'host:port' strings for
>>> 'radiusservers'?  If no port is specified, then simply use the default
>>> for that specific host. Therefore, we would not have to worry about
>>> keeping the two lists in sync. Thoughts?
>>
>>
>> If we do that we should do it for all the parameters, no? So not just
>> host:port, but something like host:port:secret:identifier? Mixing the two
>> ways of doing it would be quite confusing I think.
>>
>> And I wonder if that format wouldn't get even more confusing if you for
>> example want to use default ports, but non-default secrets.
>
> Yes, I agree. Such a format would be more confusing and I certainly
> wouldn't be in favor of it.
>
>> I can see how it would probably be easier in some of the simple cases, but I
>> wonder if it wouldn't make it worse in a lot of other cases.
>
> Ultimately, I think that it would be better off in a separate
> configuration file. Something to the effect of each line representing
> a server, something like:
>
> '<server> <port> <secret> <identifier>'
>
> With 'radiusservers' simply being the path to that file and
> 'radiusserver', etc. would remain as is. Where only one or the other
> could be provided, but not both. Though, that's perhaps would be
> beyond the scope of this patch.
>
> At any rate, I'm going to continue moving forward with testing this patch as is.

I have run through testing this patch against a small set of RADIUS
servers.  This testing included both single server and multiple server
configurations. All seems to work as expected.

-Adam