I have a control bord installed on a remote digital signage totem.
The card is connected via RS232 to an IP adapter which I can connect remotely.
I need to send it HEX commands every hour, get the answers and act according to them
(for example the command for what is the door status is: "AE 04 04 0A" and the answer is: "{EF}{04}{04}{01}" the last digit is 1=open 0=closed)
I would like to take the answers and get them on my Zabbix monitor system for alerts, like if the door is open or the temp is high.
can you give me a direction to a platform that can run this kind of automation?
It's surely doable, but it depends on the details of "IP adapter which I can connect remotely":
is it an http gateway where you post your authentication and commands? Then use an http item
is it a simple socket with no auth, just ip->rs232? Then a simple telnet/nc script called via zabbix with a system.run is the way to go
is the interaction more complex? I.e: telnet, then authenticate, then subcommand1 and so on? A system.run as well, but to call a more complex script like expect or pexpect
In the simplest case, assuming a socket on host 1.2.3.4 and port 23 that just accepts input:
echo 'AE 04 04 0A' | nc -N 1.2.3.4 23 | perl -lne 'print $1 if /(?:{\w\w}){3}{(\w\w)}/'
This will send the hex command AE 04 04 0A to the device, then print the fourth portion of the result: so if the result string is {EF}{04}{04}{01}, the command will return 01
Related
I am writing a Python surveillance script for my home.
I have manually set a static LAN IP address to my phone by it's MAC address.
The Python script should check from time to time if my phone is still connected to the network. When I disconnect the script shall then continue and start the RTSP stream in my script.
The question
What is the simplest and best way to check if my phone is connected to the network or not?
I think the simplest way would be to ping your phone from time to time. Here's a bash example which I'm sure could be adapted to python one way or another:
ping -c2 192.168.1.200 >/dev/null && echo phone is connected || echo phone is offline
Just check the return code of the ping command.
Really hoping someone here can point me in the right direction,
Expected result: SSH successfully into a remote device.
Challenge/Back story:
We have devices out in remote places around the country,
These devices do not have a fixed public IP address
(Using GSM as its internet breakout)
These devices are able to SSH and break out.
My thought, with regards to maintaining these devices is to (if possible) use a server in the cloud as a middle man, have these devices create some sort of a reverse tunnel to our middleman server then have us as admins intercept it or something to that effect.
Again to summarize, Device cannot be ssh'd into directly, but can breakout.
Aim to be able to hit their terminal from the office.
have been looking at mitmssh but not coming right on that front.
Server A (no fixed address, cannot SSH into it directly but has breakout)
Server B (standard server which can be used as a middle man
Server C (Us admins)
Tried something along the lines of "ssh user#serverA -R serverB:12345:ServerA:22"
Which creates the tunnel, but struggling with grabbing hold of that SSH connection.
I think I regularly use something very similar. My target machine connects to the machine with a stable address with:
ssh midpoint -R 2022:localhost:22
my ~/.ssh/config file knows the real HostName. My config file on my work machine defines a ProxyCommand option to use this tunnelled TCP connection. like:
Host target
ProxyCommand ssh -q midpoint nc localhost 2022
the reason for using netcat was to get ssh-agent behaving.
I've just been searching around and it seems OpenSSH now has specific handling for this (-W command line option, and JumpHost in the config file). E.g. https://stackoverflow.com/a/29176698/1358308
what is the Linux command to connect to another server using host name and port number?
how to connect to another server using only host name and port number then check if an existing process is running? the only way i see it working is to log in to the server and run the PS command. but is there a way to do it without logging in directly to the other server and connect only with host name and port number and check the running process?
If you just want to try an arbitrary connection to a given host/port combination, you could try one nmap, telnet or nc (netcat).
Note that you can't necessarily determine whether or not a process is running remotely - it might be running on that port, but simply ignore anything it sees over the port. To really be sure, you will need to run ps or netstat or etc. via ssh or etc.
If you want to use SSH from e.g. a script or, more generally, without typing in login information, then you will want to use public key authentication. Ubuntu has some good documentation on how to set this up, and it's very much applicable to other distrobutions as well: https://help.ubuntu.com/community/SSH/OpenSSH/Keys.
If you have no access to the server you're trying to list processes on at all, then I'm afraid there isn't a way to list running processes remotely (besides remote tools like nmap and so on, as mentioned earlier - you can always probe public ports without authentication [although you might make people angry if you do this to servers you don't own]). This is a feature, not a problem.
telnet connects to most of services. With it you can ensure that port is open and see hello message (if any). Also nc is more low level.
eri#eri-macro ~ $ telnet smtp.yandex.ru 25
Trying 87.250.250.38...
Connected to smtp.yandex.ru.
Escape character is '^]'.
220 smtp16.mail.yandex.net ESMTP (Want to use Yandex.Mail for your domain? Visit http://pdd.yandex.ru)
helo
501 5.5.4 HELO requires domain address.
HELO ya.ru
250 smtp16.mail.yandex.net
MAIL FROM: <someusername#somecompany.ru>
502 5.5.2 Syntax error, command unrecognized.
If there is plain text protocol you cat talk with service by keyboard. If connection is secured try openssl.
openssl s_client -quiet -connect www.google.com:443
depth=1 /C=ZA/O=Thawte Consulting (Pty) Ltd./CN=Thawte SGC CA
verify error:num=20:unable to get local issuer certificate
verify return:0
GET /
<HTML><HEAD>
If protocol is not known you may see much of hieroglyphs or just Connected to ... message.
Try this :
ssh <YOUR_HOST_NAME> 'ps auxwww'
Like Dark Falcon said in the comments, you need a protocol to communicate with the server, a port alone is useless in this case.
By default on unix (and unix like) servers, ssh is the way to go.
Remote Shell with this command. Example is cat a file on the remote machine.
rsh host port 'cat remotefile' >> localfile
host and port self explainitory
remotefile: name of some file on the machine remote logging to in home directory
localfile: name of file cat information to.
Use monitoring software (like Nagios). It looks at your processes, sensors, load and thatever you configured to watch. It continuously stores log. It alerts you by email\sms\jabber if something fails. You can access it with browser or by HTTP API.
In Linux (Ubuntu), I want to programmatically check if there is Internet connection (or if eth0 is connected).
I'm doing this because I am writing a program that requires network connection on a system that is highly prone to lose connection.
So I was thinking maybe a script that I can run periodically to check.
Can you give me good suggestions?
Here is a quick script that will accomplish what you want:
EMAIL=youremail#something.com
ping -c 5 8.8.8.8 >> /dev/null
if [ $? -eq 0 ]
then
echo "Able to reach internet!" | mail $EMAIL
else
echo "Unable to reach internet!" | mail $EMAIL
fi
Obviosly you can change the mail to something else to do depending on what your goal is
EDIT: to explain, this pings googles dns server to ensure you are connected and sends you an email one way or the other. The email part on failure will only work of course if you have a local email server on your network.
/sbin/ifconfig would be an excellent "get adapter status" command to script.
cron would be an excellent way to execute the script.
I also suggest to ping or perhaps wget some distant server (preferably the one you want to connect to). The network could work well on the local campus, but not well on intercontinental connections (e.g. because some cables has been cut).
I am looking for a tool (under linux) that will allow me to set up an end to end proxy that accepts multiple simultaneous clients on one port at one end, forwards the data to the other end with a single connection then "expands" the connection at the other end to connect back to a service that accepts multiple connections. To clarify, here is a diagram of what I want to achieve:
http://i.stack.imgur.com/rgTMd.png
(apparantly I need more then 10 rep to have the image embedded in this page)
If you're interested, the reason why I am attempting to do this is because I want to build a system that would make it easier to tunnel over arbitrary protocols, as long as the protocol supports some way to send some message from one end to another. I would put the system in between proxy end A and proxy end B in the diagram above.
Here is an example of how I want it to work:
First I will run the following commands
mkfifo backpipe
nc -l 7778 0<backpipe | tee f1 | nc localhost 7777 | tee f2 >backpipe
The "server proxy" will be running on port 7777.
The "client proxy" that the application will connect to will be running on port 8080
The client proxy will connect to port 7778
Solve for "server proxy" and "client proxy"
OpenSSH already supports this with the -D option:
ssh -D <port> -l username remotehost
A SOCKS server will listen for connections on and forward them to the other end of the SSH connection.
I've decided to code my own solution for the mean time. It's a bit of python code that accepts multiple clients and basically proxies the communication through the standard input/output. If anyone is interested, here's the code http://pastebin.com/1E45Exsy
Don't trust this code to work perfectly. I have not tested it properly and it doesn't handle disconnecting clients.
I will continue to search for a more elegant and robust solution, but this should do in the meantime. I'll post updates to the code here if I make them.