Ping 8.8.8.8 every 1 minute, after some pings the ping times out

Question

I am having an Android app which needs continuous network monitoring and I require to be notified when I have internet and when not. I have tried Android connectivity manager, which only tells if the internet wifi is connected or not, but doesn't tell if there is reachability. So I used the following ping method to check the reachability.

    private fun isOnline(): Boolean {
        return try {
            val timeoutMs = 1500
            val sock = Socket()
            val socketAddress = InetSocketAddress("8.8.8.8", 53)
            sock.connect(socketAddress, timeoutMs)
            sock.close()
            true
        } catch (e: IOException) {
            Logger.e(TAG, e.toString())
            false
        }
    }

Now to keep checking this every 1 minute I am using a fixedRateTimer which will call this method every 1 minute and notify accordingly.

Now the problem I am facing is, this works fine for few hours and I get proper connection status. But after few hours the ping starts timing out. I get a timeout exception every alternate ping. I want to understand few things,

First thing, is it okay to ping for every 1 minute to check the network?
Can the client be blocked by Google for frequent pings?
Or is it anything related to the ISP?
Is there a better approach in android to achieve what I want?

Any advice would be appreciated. Thanks in advance!

PS : I have also tried onCapabilitiesChanged and the callbacks are not immediate for every connection and disconnection, though the google documentation says callbacks will be immediate.

user_115145 · Answer

but doesn't tell if there is reachability. So I used the following ping method to check the reachability

First, that is not a ping. That is opening and closing a socket.

Second, it can only tell you if you can open a socket connection to that IP address. It does not tell you if you can access anything else. So, this is subject to false positives (you can reach 8.8.8.8 but not your real server) and false negatives (8.8.8.8 is blocked by network management, but your real server is not).

Now to keep checking this every 1 minute I am using a fixedRateTimer which will call this method every 1 minute and notify accordingly.

That will only work so long as your process is running, and only until you lose Internet access due to Doze mode/app standby/manufacturer-specific power management solutions.

First thing, is it okay to ping for every 1 minute to check the network?

It has flaws. "Okay" is a subjective measure; only you can decide whether it is "okay" for you.

Can the client be blocked by Google for frequent pings?

This is not a ping. It is certainly within Google's power to take action for buggy clients like this.

Or is it anything related to the ISP?

There are lots of pieces involved in an Android device reaching 8.8.8.8:

The network management for whatever WiFi network the phone is using for connectivity (where relevant)
The mobile carrier or ISP
The various other ISPs between you and Google
Google's own network management

Any of them could take steps, if they so chose.

Is there a better approach in android to achieve what I want?

I would aim to eliminate the "need" entirely, as Android and device manufacturers will be fighting you every step of the way.

At minimum:

Do a valid expected operation, such as an actual ping; and
Do it against a relevant server

IIRC, 8.8.8.8 is a DNS server. If your app is a DNS client, you are welcome perform a valid, useful DNS operation against 8.8.8.8. If your app is not a DNS client, quit messing with somebody else's server. Run your own server and test reaching it. For example, you could run a Web server and test whether you can retrieve your robots.txt file.

user_139985 · Answer

Most of the question has been answered, but I want to pick up on the most important one.

First thing, is it okay to ping for every 1 minute to check the network?

No. It is not OK.

It is wasteful

You are consuming Google's resources. Resources that you are not paying for. If everyone did what you are doing it would cost Google a lot of money ... to run a much larger fleet of DNS servers, etc to cope with bazillions of vacuous connections.

You are also consuming resources in the along the route from the user's app to Google with the (unnecessary) network traffic.

This would also apply if you were doing real (ICMP) pings, though not to the same extent.

And bear in mind, this is also consuming electricity. And that means more fossil fuel is burned.

It may be incurring costs for the user

Depending on the what their mobile phone plan is, this may be costing the user of your app network charges. Each of those connections your App is making probably being metered. If they are not aware of this ... or they can't turn this (mis-)feature off, they could get rather annoyed about this. (I would be!)

It doesn't actually work

What you are doing doesn't actually test if the internet is available. What you are actually doing is seeing if your App can connect to the Google DNS services. But the fact that the DNS server is accepting connections doesn't mean that the real services that the user wants to use will be accessible and working. (And vice versa!)

As you noted, connections will occasionally fail for reasons that are probably due to transient problems that resolve themselves. There is nothing you can do about that. That could be a false negative for the internet being "up".

Even if there was a reliable way to find out if the internet is "working", your "pinging" is only giving you a single sample. The internet could go "down" (or come back "up") any time in the up to 60 seconds between your pings. More false negatives and positives.

And as noted, Google DNS is not the same as "the internet", and "the internet" is not the same as the service that the user of you App is really interested in.

Your app doesn't REALLY need this information

The user does not need to know minute by minute that the internet is available.

Most of the time a typical user is doing something else.

They only actually need to know if they are actively using some service. And even then, knowing that the internet was up 60 seconds ago is probably no help to them.

Unfortunately, the only way that the user can tell if the service they are talking to is available right now ... is to actually try to use it.

So what is the real solution?

IMO, there are two approaches:

Forget it. In most cases, the user really doesn't need to know. It is not actually going to materially effect the user if your App does not distinguish "service down" from "internet down".
If you can't forget it.
- Implement an end-point on your service that you can ping ... and pay the bills!
- If you are trying to implement this in an App where you are talking to someone else's services, stop free-loading on Google. If you want an "internet is up/down" feature in your App, implement your own service for doing this ... and pay the bills.
Note that you will still have false positives and false negatives to deal with. There is no solution to that. It is a fundamental property of the internet.