Is directly echo the php server variable for user agent a security hole?

Is this script vuln to php/js code injection? In my quick test i changed the useragent to a php script but it will not be executed just printed. if change user agent to a javascript code i receive i connection refused by the webserver.

so am i safe with this type of script?

<?php  $  u=$  _SERVER['HTTP_USER_AGENT'] ?> <html> <pre>string</pre> <?php echo $  u; ?> </html> 

Ubuntu 18.04: No polkit authentication agent found

I get the error message above when I try to write to a file I don’t have permission to in Visual Studio Code. I choose “Retry as sudo”: Click sudo and get the error: Error message

This only happens when I connect to the machine from my PC using ssh and X11-forwarding. Not when I run from gnome directly on Ubuntu machine.

Help appreciated.

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What is the purpose of user agent node-fetch fetching just the base URL from our site?

The user agent node-fetch/1.0 (+ has been fetching the base URL from IP’s belonging to

It is fairly aggressive and coming in from quite a number of IP addresses and I’m wondering why the user agent only fetches the base URL and no other resources are loaded.

user agent

I’d like to block it but am not sure it would be wise.

HTTP Response to a SAMLResponse POST by user agent

Looking at RFC2616, is it acceptable to return an HTTP 200 (page load) as a response to a SAMLResponse post to the SP? i.e. the user-agent loads a page instead of redirecting via a 302 / 303?

Looking for clarity on 3.4.5 here – does the response to a SAMLResponse POST refer to point 2 or 5?

thanks in advance.

Getting Active: active (exited) status on code deploy agent aws

I installed Code Deploy agent on my ubuntu server.

Ouput of sudo service codedeploy-agent status :

   Active: active (exited) since Sat 2019-07-20 18:16:37 UTC; 4s ago      Docs: man:systemd-sysv-generator(8)   Process: 4968 ExecStart=/etc/init.d/codedeploy-agent start (code=exited, status=0/SUCCESS)  

How to make active(exited) to active(running) ?

Value flow (and economics) in stacked reinforcement learning systems: agent as reinforcement environment for other agents?

There is evolving notion of stacked reinforcement learning systems, e.g. – where one RL systems executes actions of the second RL system and it itself executes action of the thrid and the reward and value flows back.

So, one can consider the RL system RLn with:

  • S – space of states;
  • A={Ai, Ainner, Ao} – space of actions which can be divided into 3 subspaces:
    • Ai – actions that RLn exposes to other RL systems (like RLn-1, RLn-2, etc.) and for whome the RLn provides reward to those other systems;
    • Ainner – actions that RLn executes internally under its own will and life;
    • Ao – actions that RLn imports from other RL systems (like RLn+1, RLn+2, etc.) and that RLn executes on the other systems and form which RLn gets some rewards, that can be used for providing rewards for Ai actions.

So, one can consider the network (possibly hierarchical) of RL systems . My questions are:

  • is there some literature that consider such stacks/networks of reinforcement learning systems/environments?
  • is there economic research about value flow, about accumulation of wealth, about starvation and survival proceses and evolution in such stacks/networks of RL systems/environments

Essentially – my question is about RL environments that can function in the role of agents for some other environments and about agents that can function in the role of environemnts for some other agents. How computer science/machine learning/artificial intelligence name such systems, what methods are used for research and how the concepts of economics/governance/preference/utility are used in the research of evolution of such systems?