[Hampshire] Raspberry Pi, RS485 and libmodbus

[Roger Munford via Hampshire]

I am trying to connect an energy monitor to a raspberry pi equipped with 
a small RS485 card from AB electronics. Effectively the card is just an 
interface chip between the pi's GPIO pins and the RS485 bus which is 
just 3 wires.


I have installed libmodbus and followed the instructions to disable the 
serial port login.


Originally I was working with the Bluetooth equipped RP3 but reverted to 
RP2 running wheezy because bluetooth complicates things and I thought I 
would avoid it.


If anybody is familiar with this sort of setup and may have possibly 
come up against the following problem I would be grateful.


I have done the "make check" which tests the libmodbus installation. I 
have modified the  "test" programme for my environment and the 
initialisation and connection are OK but when I try to read the 
registers, I get a timeout. The fault could be anywhere.


Thanks,

Roger



nd connect correc

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Re: [Hampshire] ufw

[Gareth via Hampshire]

Hi rob
You could always test it from the machine you are allowing...
Use telnet and try to connect to another port that you know is running a
service on the destination machine..

Thanks
G

On 3 Nov 2017 3:41 p.m., "Rob Malpass via Hampshire" <
hampshire@mailman.lug.org.uk> wrote:

> Thanks both – so if I do
>
>
>
> sudo ufw allow from 192.168.0.99 to any port 22
>
>
>
> then am I doing anything other than saying 192.168.0.99 can ssh in to this
> machine?   This is what I’m trying to achieve but the “any” is confusing me
> somewhat – though the rule itself does seem to be doing what I want.
>
>
>
> Cheers
>
> Rob
>
>
>
> *From:* Hampshire [mailto:hampshire-boun...@mailman.lug.org.uk] *On
> Behalf Of *Gareth Evans via Hampshire
> *Sent:* 03 November 2017 15:28
> *To:* Peter B.; Hampshire LUG Discussion List
> *Subject:* Re: [Hampshire] ufw
>
>
>
> man ufw doesn't seem to have much to say on the matter, but
>
>
>
> https://help.ubuntu.com/community/UFW
>
>
>
> suggests "any" in this context means any destination IP address (given
> that there may be many associated with a host):
>
>
>
> *Allow by specific port, IP address and protocol*
>
>
>
> sudo ufw allow from  to  port  proto
> 
>
>
>
> *example: allow IP address 192.168.0.4 access to port 22 using TCP*
>
>
>
> sudo ufw allow from 192.168.0.4 to any port 22 proto tcp
>
>
>
>
>
>
>
> On Fri, 3 Nov 2017, at 14:57, Peter B. via Hampshire wrote:
>
> From any port on y Maybe?
>
>
>
> On 3 Nov 2017 14:53, "Rob Malpass via Hampshire" <
> hampshire@mailman.lug.org.uk> wrote:
>
> Hi all
>
>
>
> Simple question (I hope).   If I’m opening port x from ip address y on my
> network with the following command
>
>
>
> sudo ufw allow from y to any port x
>
>
>
> …then where does the “any” come from?   Anyone know?   Seems strange to
> say “any port” then list the port number – unless I’ve misunderstood the
> rule.
>
>
>
> Cheers
>
> Rob
>
>
>
> --
>
> Please post to: Hampshire@mailman.lug.org.uk
>
> Web Interface: https://mailman.lug.org.uk/mailman/listinfo/hampshire
>
> LUG URL: http://www.hantslug.org.uk
>
> --
>
> --
>
> Please post to: Hampshire@mailman.lug.org.uk
>
> Web Interface: https://mailman.lug.org.uk/mailman/listinfo/hampshire
>
> LUG URL: http://www.hantslug.org.uk
>
> --
>
>
>
> --
> Please post to: Hampshire@mailman.lug.org.uk
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> LUG URL: http://www.hantslug.org.uk
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>
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Re: [Hampshire] ufw

[Gareth Evans via Hampshire]

My understanding would agree with yours, but "machine" is the key point.
If you had mulltiple IP addresses on your server, "any" would allow
192.168.0.99 to ssh into any of them.  If you only have one, it doesn't
matter, but might be worth bearing in mind in case you set up another
which you don't want 192.168.0.99 to be able to ssh into.   In this case
you would need to replace "any" with the IP address you do want to be
ssh'd into.


On Fri, 3 Nov 2017, at 15:41, Rob Malpass via Hampshire wrote:
> Thanks both – so if I do


>  


> sudo ufw allow from 192.168.0.99 to any port 22


>  


> then am I doing anything other than saying 192.168.0.99 can ssh in to
> this machine?   This is what I’m trying to achieve but the “any” is
> confusing me somewhat – though the rule itself does seem to be doing
> what I want.>  


> Cheers


> Rob


>  


> *From:* Hampshire [mailto:hampshire-boun...@mailman.lug.org.uk] *On
> Behalf Of *Gareth Evans via Hampshire *Sent:* 03 November 2017 15:28
> *To:* Peter B.; Hampshire LUG Discussion List *Subject:* Re:
> [Hampshire] ufw>  


> man ufw doesn't seem to have much to say on the matter, but


>  


> https://help.ubuntu.com/community/UFW


>  


> suggests "any" in this context means any destination IP address (given
> that there may be many associated with a host):>  


>> *Allow by specific port, IP address and protocol*


>>  


>> sudo ufw allow from  to  port 
>> proto >>  


>> *example: allow IP address 192.168.0.4 access to port 22 using TCP*>>  


>> sudo ufw allow from 192.168.0.4 to any port 22 proto tcp


>  


>  


>  


> On Fri, 3 Nov 2017, at 14:57, Peter B. via Hampshire wrote:


>> From any port on y Maybe?


>>  


>> On 3 Nov 2017 14:53, "Rob Malpass via Hampshire"
>>  wrote:>>> Hi all


>>>  


>>> Simple question (I hope).   If I’m opening port x from ip address y
>>> on my network with the following command>>>  


>>> sudo ufw allow from y to any port x


>>>  


>>> …then where does the “any” come from?   Anyone know?   Seems strange
>>> to say “any port” then list the port number – unless I’ve
>>> misunderstood the rule.>>>  


>>> Cheers


>>> Rob


>>>  


>>> --


>>> Please post to: Hampshire@mailman.lug.org.uk


>>> Web Interface: https://mailman.lug.org.uk/mailman/listinfo/hampshire>>> LUG 
>>> URL: http://www.hantslug.org.uk


>>> --


>> --


>> Please post to: Hampshire@mailman.lug.org.uk


>> Web Interface: https://mailman.lug.org.uk/mailman/listinfo/hampshire>> LUG 
>> URL: http://www.hantslug.org.uk


>> --


>  


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Re: [Hampshire] ufw

[Rob Malpass via Hampshire]

Thanks both – so if I do

 

sudo ufw allow from 192.168.0.99 to any port 22 

 

then am I doing anything other than saying 192.168.0.99 can ssh in to this 
machine?   This is what I’m trying to achieve but the “any” is confusing me 
somewhat – though the rule itself does seem to be doing what I want.

 

Cheers

Rob

 

From: Hampshire [mailto:hampshire-boun...@mailman.lug.org.uk] On Behalf Of 
Gareth Evans via Hampshire
Sent: 03 November 2017 15:28
To: Peter B.; Hampshire LUG Discussion List
Subject: Re: [Hampshire] ufw

 

man ufw doesn't seem to have much to say on the matter, but

 

https://help.ubuntu.com/community/UFW

 

suggests "any" in this context means any destination IP address (given that 
there may be many associated with a host):

 

Allow by specific port, IP address and protocol

 

sudo ufw allow from  to  port  proto 


 

example: allow IP address 192.168.0.4 access to port 22 using TCP

 

sudo ufw allow from 192.168.0.4 to any port 22 proto tcp

 

 

 

On Fri, 3 Nov 2017, at 14:57, Peter B. via Hampshire wrote:

>From any port on y Maybe?

 

On 3 Nov 2017 14:53, "Rob Malpass via Hampshire"  
wrote:

Hi all

 

Simple question (I hope).   If I’m opening port x from ip address y on my 
network with the following command

 

sudo ufw allow from y to any port x

 

…then where does the “any” come from?   Anyone know?   Seems strange to say 
“any port” then list the port number – unless I’ve misunderstood the rule.

 

Cheers

Rob

 

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Re: [Hampshire] ufw

[Gareth Evans via Hampshire]

man ufw doesn't seem to have much to say on the matter, but

https://help.ubuntu.com/community/UFW

suggests "any" in this context means any destination IP address (given
that there may be many associated with a host):
> *Allow by specific port, IP address and protocol*
> 
> sudo ufw allow from  to  port  proto
> > 
> *example: allow IP address 192.168.0.4 access to port 22 using TCP**
*> 
> sudo ufw allow from 192.168.0.4 to any port 22 proto tcp



On Fri, 3 Nov 2017, at 14:57, Peter B. via Hampshire wrote:
> From any port on y Maybe?
> 
> On 3 Nov 2017 14:53, "Rob Malpass via Hampshire"
>  wrote:>> Hi all__


>> __ __


>> Simple question (I hope).   If I’m opening port x from ip address y
>> on my network with the following command__>> __ __


>> sudo ufw allow from y to any port x__


>> __ __


>> …then where does the “any” come from?   Anyone know?   Seems strange
>> to say “any port” then list the port number – unless I’ve
>> misunderstood the rule.__>> __ __


>> Cheers__


>> Rob__


>> 
>> --
>>  Please post to: Hampshire@mailman.lug.org.uk
>>  Web Interface: https://mailman.lug.org.uk/mailman/listinfo/hampshire>>  LUG 
>> URL: http://www.hantslug.org.uk
>>  --
> --
> Please post to: Hampshire@mailman.lug.org.uk
> Web Interface: https://mailman.lug.org.uk/mailman/listinfo/hampshire
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Re: [Hampshire] ufw

[Ben Parsonage via Hampshire]

I am not an expert but acordinng to the man page the long format appears to be
ufw   to   

So this will allow a connection from Y to any destination on port X. 

On 3 November 2017 14:57:02 GMT+00:00, "Peter B. via Hampshire" 
 wrote:
>From any port on y Maybe?
>
>On 3 Nov 2017 14:53, "Rob Malpass via Hampshire" <
>hampshire@mailman.lug.org.uk> wrote:
>
>> Hi all
>>
>>
>>
>> Simple question (I hope).   If I’m opening port x from ip address y
>on my
>> network with the following command
>>
>>
>>
>> sudo ufw allow from y to any port x
>>
>>
>>
>> …then where does the “any” come from?   Anyone know?   Seems strange
>to
>> say “any port” then list the port number – unless I’ve misunderstood
>the
>> rule.
>>
>>
>>
>> Cheers
>>
>> Rob
>>
>> --
>> Please post to: Hampshire@mailman.lug.org.uk
>> Web Interface: https://mailman.lug.org.uk/mailman/listinfo/hampshire
>> LUG URL: http://www.hantslug.org.uk
>> --
>>

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Re: [Hampshire] ufw

[Peter B. via Hampshire]

>From any port on y Maybe?

On 3 Nov 2017 14:53, "Rob Malpass via Hampshire" <
hampshire@mailman.lug.org.uk> wrote:

> Hi all
>
>
>
> Simple question (I hope).   If I’m opening port x from ip address y on my
> network with the following command
>
>
>
> sudo ufw allow from y to any port x
>
>
>
> …then where does the “any” come from?   Anyone know?   Seems strange to
> say “any port” then list the port number – unless I’ve misunderstood the
> rule.
>
>
>
> Cheers
>
> Rob
>
> --
> Please post to: Hampshire@mailman.lug.org.uk
> Web Interface: https://mailman.lug.org.uk/mailman/listinfo/hampshire
> LUG URL: http://www.hantslug.org.uk
> --
>
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[Hampshire] ufw

[Rob Malpass via Hampshire]

Hi all

 

Simple question (I hope).   If I'm opening port x from ip address y on my
network with the following command

 

sudo ufw allow from y to any port x

 

.then where does the "any" come from?   Anyone know?   Seems strange to say
"any port" then list the port number - unless I've misunderstood the rule.

 

Cheers

Rob

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