Shell does not support network backends

[radfanSC]

Describe the bug
I have created the example Telnet console application for the board FRDM-K64F under Windows.
Although I get a connection to the board with a telnet client, but there are no inputs and outputs on the client possible.

To Reproduce
Steps to reproduce the behavior:

1. cd samples/net/telnet
2. mkdir build; cd build
3. cmake -GNinja -DBOARD=frdm_k64f ..
4. ninja
5. Put the result zephyr/zephyr.bin into the board
6. wait until dhcpv4 has finished
7. connect with a Telnet-client

Expected behavior
Input/Output to the Shell via Telnet-console

console output
uart:~$ ***** Booting Zephyr OS zephyr-v1.13.0-2584-g8ec7c73d2e *****
[00:00:00.008,451] net_config.net_config_init: Initializing network
[00:00:00.008,474] net_config.setup_ipv4: IPv4 address: 10.0.0.62
[00:00:00.008,489] net_config.setup_dhcpv4: Running dhcpv4 client...
[00:00:06.021,795] net_dhcpv4.dhcpv4_handle_msg_ack: Received: 10.0.1.32
[00:00:06.021,829] net_config.ipv4_addr_add_handler: IPv4 address: 10.0.1.32
[00:00:06.021,832] net_config.ipv4_addr_add_handler: Lease time: 86400 seconds
[00:00:06.021,846] net_config.ipv4_addr_add_handler: Subnet: 255.255.254.0
[00:00:06.021,859] net_config.ipv4_addr_add_handler: Router: 10.0.0.254
[00:00:08.020,315] net_telnet.telnet_setup_server: Telnet console enabled on AF_INET
[00:00:08.020,341] net_telnet.telnet_console_init: Telnet console initialized
[00:00:08.020,346] net_telnet_sample.main: Starting Telnet sample
[00:00:19.963,597] net_telnet.telnet_accept: Telnet client connected (family AF_INET)

Environment:

• OS: Windows
• Toolchain: gccarmemb Version 7.3.1

[jukkar]

Tested this also with native_posix, I am not seeing any output from nc 2001:db8::1 23.

[nordic-krch]

Please specify as i'm not sure what is the issue. Shell over uart stops working? Or telnet? afaik, there is no shell over network.

[radfanSC]

The shell is working over uart but not over telnet.
In the documentation stands:
"You are now connected, and as for the UART console, you can type in your commands and get the output through your telnet Client"

[nordic-krch]

@jukkar did legacy shell supported network transport? New one doesn't yet, so that would look like a misleading documentation after switching to new shell.

[tbursztyka]

@nordic-doki that sounds like a bug introduced by new shell. Legacy stuff was working properly, but remember that it was far easier back then: all was using printk below...

[agansari]

This issue look more like a feature than a bug @galak .
I've tested in qemu and posix, but there is not shell in telnet console. It's not restricted to k64f.

Yes, the telnet cannot be used atm as the shell is missing support for network transport.

Originally posted by @jukkar in #14691 (comment)

[jukkar]

This is generic shell issue, fixing title.

[nordic-krch]

Could we reassign to someone else? Adding shell network backend is not in my plans and scope.