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Brian J. Murrell | 21 Feb 2012 22:23
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remote execute hook prior to evaluating params

Currently I have in my params:

CGCOIF=$(ssh root <at> gw "/sbin/uci -p /var/state get network.wan0.ifname")
IGSIF=$(ssh root <at> gw "/sbin/uci -p /var/state get network.wan1.ifname")
PPPEIF=$(ssh root <at> gw "/sbin/uci -p /var/state get network.pppoe_ether.device")
CGCO_GATEWAY=$(ssh root <at> gw "/sbin/uci -p /var/state get network.wan0.gateway")
IGS_GATEWAY=$(ssh root <at> gw "/sbin/uci -p /var/state get network.wan1.gateway")
IGS_ADDRESS=$(ssh root <at> gw "/sbin/uci -p /var/state get network.wan1.ipaddr")

Which is a whole lotta round trips all requiring their own crypto
authentication, etc.

I wonder if there is an available hook that I could use to go fetch
all of that in a single round-trip (i.e. and store it locally and then
source that local file for the values).

I suppose if params is just sourced and executed sh script I could just
do the single execution and use the result.  I'm not sure that it is though.

Thoughts?

b.


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Tom Eastep | 21 Feb 2012 22:38
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Re: remote execute hook prior to evaluating params

On 02/21/2012 01:23 PM, Brian J. Murrell wrote:
> Currently I have in my params:
> 
> CGCOIF=$(ssh root <at> gw "/sbin/uci -p /var/state get network.wan0.ifname")
> IGSIF=$(ssh root <at> gw "/sbin/uci -p /var/state get network.wan1.ifname")
> PPPEIF=$(ssh root <at> gw "/sbin/uci -p /var/state get network.pppoe_ether.device")
> CGCO_GATEWAY=$(ssh root <at> gw "/sbin/uci -p /var/state get network.wan0.gateway")
> IGS_GATEWAY=$(ssh root <at> gw "/sbin/uci -p /var/state get network.wan1.gateway")
> IGS_ADDRESS=$(ssh root <at> gw "/sbin/uci -p /var/state get network.wan1.ipaddr")
> 
> Which is a whole lotta round trips all requiring their own crypto
> authentication, etc.
> 
> I wonder if there is an available hook that I could use to go fetch
> all of that in a single round-trip (i.e. and store it locally and then
> source that local file for the values).
> 
> I suppose if params is just sourced and executed sh script I could just
> do the single execution and use the result.  I'm not sure that it is though.
> 
> Thoughts?

I guess my first question is "How are you using these variables?". In
configuration files, the first three can be replaced by "Runtime Address
Variables"; see
http://www.shorewall.net/configuration_file_basics.htm#Variables.

Shorewall will detect the gateway addresses for you and store them in
shell variables in the generated script, but so far I haven't
implemented gateway Runtime Address Variables, though. Not hard to do,
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Brian J. Murrell | 21 Feb 2012 23:08
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Re: remote execute hook prior to evaluating params

On 12-02-21 04:38 PM, Tom Eastep wrote:
> On 02/21/2012 01:23 PM, Brian J. Murrell wrote:
>> Currently I have in my params:
>>
>> CGCOIF=$(ssh root <at> gw "/sbin/uci -p /var/state get network.wan0.ifname")
>> IGSIF=$(ssh root <at> gw "/sbin/uci -p /var/state get network.wan1.ifname")
>> PPPEIF=$(ssh root <at> gw "/sbin/uci -p /var/state get network.pppoe_ether.device")
>> CGCO_GATEWAY=$(ssh root <at> gw "/sbin/uci -p /var/state get network.wan0.gateway")
>> IGS_GATEWAY=$(ssh root <at> gw "/sbin/uci -p /var/state get network.wan1.gateway")
>> IGS_ADDRESS=$(ssh root <at> gw "/sbin/uci -p /var/state get network.wan1.ipaddr")

FWIW, the following seems to do the trick in params:

ssh root <at> gw "echo CGCOIF=\$(/sbin/uci -p /var/state get network.wan0.ifname)
echo IGSIF=\$(/sbin/uci -p /var/state get network.wan1.ifname)
echo PPPEIF=\$(/sbin/uci -p /var/state get network.pppoe_ether.device)
echo CGCO_GATEWAY=\$(/sbin/uci -p /var/state get network.wan0.gateway)
echo CGCO_ADDRESS=\$(/sbin/uci -p /var/state get network.wan0.ipaddr)
echo IGS_GATEWAY=\$(/sbin/uci -p /var/state get network.wan1.gateway)
echo IGS_ADDRESS=\$(/sbin/uci -p /var/state get network.wan1.ipaddr)" > foo
eval $(cat foo)
rm foo

I'm sure there's some quoting magic to eliminate the "foo"
intermediate, but it's just too late in the day to keep messing with it.

> I guess my first question is "How are you using these variables?".

Some examples:
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Tom Eastep | 21 Feb 2012 23:14
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Re: remote execute hook prior to evaluating params

ll.net/configuration_file_basics.htm#Variables.
> 
> Ahhh.  &<ifname>?  Note that those first three variables in my list
> above are interface names not their addresses.  The .ipaddr ones are
> addresses.  Can I assume these runtime variables will work for
> shorewall-lite installations?

Yes.

> 
>> Shorewall will detect the gateway addresses for you and store them in
>> shell variables in the generated script, but so far I haven't
>> implemented gateway Runtime Address Variables, though. Not hard to do,
>> though...
> 
> Is this answering my question about application in shorewall-lite
> configurations perhaps?

Yes.
>  
> I guess ultimately it would be nice to generalize my above ssh-and-eval
> for an arbitrary list of <variable>=<the-result-of-some-command-on-gateway>
> but with optimizing the remote executions into a single round-trip.
> 
> The above trick does work though it not entirely straightforward for
> the average user to figure out.

You could run a script on the remote system that simply returned a list
of assignment statements separated by semicolons or newlines that you
could then just source locally.
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Brian J. Murrell | 22 Feb 2012 03:19
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Re: remote execute hook prior to evaluating params

On 12-02-21 05:14 PM, Tom Eastep wrote:
> 

So I eliminate two of my "remote variables" using &<ifname> but since I
have to fetch others anyway...

> You could run a script on the remote system that simply returned a list
> of assignment statements separated by semicolons or newlines that you
> could then just source locally.

Right which is effectively what I have done with:

ssh root <at> gw "echo CGCOIF=\$(/sbin/uci -p /var/state get network.wan0.ifname)
echo IGSIF=\$(/sbin/uci -p /var/state get network.wan1.ifname)
echo PPPEIF=\$(/sbin/uci -p /var/state get network.pppoe_ether.device)
echo CGCO_GATEWAY=\$(/sbin/uci -p /var/state get network.wan0.gateway)
echo CGCO_ADDRESS=\$(/sbin/uci -p /var/state get network.wan0.ipaddr)
echo IGS_GATEWAY=\$(/sbin/uci -p /var/state get network.wan1.gateway)
echo IGS_ADDRESS=\$(/sbin/uci -p /var/state get network.wan1.ipaddr)" > foo
eval $(cat foo)
rm foo

and indeed, I can replace the "eval $(cat foo)" with ". ./foo".

Also, my remote address resolution provides the right level of
abstraction for openwrt.  wan0 and wan1 are consistent across
routers whereas their real interface values (eth0.2 and pppoe-wan1)
are implementation dependent.

That said, &eth0.2 and &pppoe-wan1 in my config files instead of the
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Gmane