Since both synpatic and terminal are deemed applications and vpn's are meant to direct all traffic, does that mean both are going thru the vpn client? Synaptic package manager accesses external repo's only?I do not have an internal repo to access.

I did spot my vpn ip multiple times in the routing results when I ran based on seeing the vpn ip the in results can we say:
- a gui synaptic package manager will go thru your vpn client?
- that when you use terminal to download something from your distro's repo the traffic will go thru your vpn client?

No, I wanted to say it does not depend on the app itself, whether it is apt, synaptic, wget, curl, firefox or whatever else you might use to connect to another host.
Synaptis is a graphical tool (not a command line tool).

No, if my PC is already connected to that corporate network I don't need to use vpn to reach internal resources.
If you mean the corporate vpn I don't need that at all to download anything from the net, it is only required if I want to reach anything inside. Including package manager, terminal or any other tool.


You need to think about vpn as a "highway" (or tunnel), it connects two points together, let's say it connects two subnets together. Because of the nature of this highway you don't need to take care of any distance, any problems (during the travel), because virtually these subnets are just connected to each other (reachable using this protected highway) despite the fact the connection itself goes thru a lot of insecure and open hosts.
Your router will tell to your host (in case of a request) if a (tcp/ip) package should go thru this highway or should find another way to reach its destination. (that's why it is called roouter).
Router has no idea where is this package coming from, if it was initiated by a program, gui, terminal, kernel, whatever, it is not important.

In may case the two subnets are my local home network and the corporate network and I can only reach company resources if I use this highway, there is no other route to internal hosts. But obviously the usage of it is allowed only for members.

If a retiree i.e. someone not working in a corporate setting, needed to download something from their official distro's repo using terminal commands, and the retiree has vpn client switched on i.e. connected to a random foreign IP, will these terminal commands get tunnelled via the vpn client? If yes then are you also saying the router not the vpn client decides if this gets tunnelled? Does synaptic go thru the vpn tunnel in this example too?

it is the router, that decides where to go, so you need to configure your router to be able to decide. When we start a vpn client, it usually tells the router the address range that can be reached with the tunnel (the router is informed about the new tunnel). Again, when you shut down your vpn client it will tell the router that the tunnel is not available any more. A random foreign ip is usually not tunneled, but occasionally it might be if it belongs to that address range.
(I don't know what kind of vpn do you have, how is it configured and what url do you want to reach, but your router does know the direction to use)

I think this description is slightly off.

A router acts as a director of traffic and all traffic reaching it is sorted and directed by the routing table on the router itself. Once a VPN is connected the gateway router sees that as a connection that is established and simply routes the traffic accordingly.

A PC that originates a VPN acts similarly. The routing table on the PC also sorts and directs traffic. When the VPN is active the pc routing table has 2 routes of interest.
Traffic is sorted and that designated as for routing via the VPN is directed to the tun0 device while all other traffic is sent to the local net or the gateway router. This means the local routing table on the PC is important so that apps connecting to an ip via the tunnel can be directed properly. Traffic not directed to an ip via the tunnel is sent via the default routing.

What this means is that there is a traffic split in the highway directly on the PC and tunnel traffic is separated from the remainder before it ever leaves the PC. The gateway router has no control over the traffic via the VPN that originates on the PC.

It also means the routing on the PC itself is critical to answering the original question here.

If your VPN is configured to route all traffic thru it, then it will route all traffic thru it. It makes no difference if that traffic is the result of the OS or an app you ran from a gui or from a terminal or from voice assistant, that is irrelevant. Traffic is traffic.

If you will simply post, using "code tags," the exact output of your route command, and tell us what URL or IP-address you are trying to connect to, we will now very-patiently explain it to you.

The route command applies a very specific set of rules to every IP-address that is presented to the Linux network-stack for delivery, telling it which "network interface" should handle the traffic, and which address is the "gateway." The final rule is a "catch-all" which handles everything else, and the rules are applied top-to-bottom.

Your VPN inserts itself into that list at one or more places, using a "virtual network device" to divert the traffic to its own software.

is /sbin/route the only command that will show if synaptic and terminal are being directed to the vpn tunnel?

But not necessarily all traffic?

Is there a way to tell if synaptic and terminal commands are designated for routing via the VPN tun0 device? By defualt does this vary on linux distro's?

So there are two routers and 2 routing tables, one external one connected to wall socket and another within the PC?

You're missing the point. It has nothing to do with what app you use it from. It's like you're not reading what people reply with. It depends where you're connecting to. Only. If you have all traffic set to go thru the vpn, then all traffic will go thru the VPN. It has nothing to do with OS or distro or anything like that - you could run a vpn client on your router for example if you wanted and get the same thing.

If you configured your vpn to only apply to certain domain or ip range, then only connections to that domain or ip range would go thru the VPN. Like for a corporate vpn, you might configure it to only apply for companyname.net adresses, but let everything else go straight to the internet. In that kinda case, companyname.net is probably not even accessible directly from the internet, they will have companyname.com as their public website which is unrelated to the internal network you use the vpn to join. This would likely be preconfigured by the company's IT department for you so you could work from home, but if you do regular web browsing, it won't appear to be coming from the companies IP, it'll be coming from yours.

additionally it is not the app (terminal, synaptic, firefox, whatever) which manages the network connection(s), routing and related things. None of them is capable to do that. They know in most cases just an URL, hostname or something similar, and the OS itself (including the kernel and some services) will do the real routing, network communication, data transfer.

Where is the vpn in the above route table?

Will the routing table reveal my real IP address?

Configuring all traffic to go thru the vpn is soley by the pc routing table?
To check if all traffic is going thru my vpn I would use use /sbin/route? The vpn client settings do not decide configuration rather the pc routing table decides?

It does not show my ip at 193.142.xxx.xxx
example...
so, just show it to us so we can see if it all links up before it goes into the vpn tunnel. :-)

btw, how does mine look?

Can we use Glenn's to answer my questions?