tcp_terminal on linux

[Prashanth Mundkur]

Hi,

I'm trying to use tcp_terminal on linux. It of course prominently says:

# TODO: Add support for Linux via user-level networking (using the
# tun/tap proxy driver at os/src/drivers/nic/linux)

After disabling the have_spec check, I can compile and run it. After
setting the suid bit on drivers/nic/spec/linux/nic_drv to allow it to
access /dev/net/tun, I get the following output:

genode build completed
using 'core-linux' as 'core'
using 'ld-linux.lib.so' as 'ld.lib.so'
using 'linux_timer_drv' as 'timer'
spawn ./core
Genode 16.11-146-gc16ee83 <local changes>
17592186044415 MiB RAM assigned to init
[init] parent provides
[init] service "ROM"
[init] service "RAM"
[init] service "IRQ"
[init] service "IO_MEM"
[init] service "IO_PORT"
[init] service "PD"
[init] service "RM"
[init] service "CPU"
[init] service "LOG"
[init] child "timer"
[init] RAM quota: 798720
[init] ELF binary: timer
[init] priority: 0
[init] provides service Timer
[init] child "nic_drv"
[init] RAM quota: 3944448
[init] ELF binary: nic_drv
[init] priority: 0
[init] provides service Nic
[init] child "tcp_terminal"
[init] RAM quota: 2371584
[init] ELF binary: tcp_terminal
[init] priority: 0
[init] provides service Terminal
[init] child "test-terminal_echo"
[init] RAM quota: 798720
[init] ELF binary: test-terminal_echo
[init] priority: 0
[init] child "nic_drv" announces service "Nic"
[init -> test-terminal_echo] Warning: using legacy main function, please convert to 'Component::construct'
[init] child "timer" announces service "Timer"
[init -> tcp_terminal] using the pipe libc plugin
[init -> tcp_terminal] init_nic_dhcp
[init -> tcp_terminal] Using DHCP for interface configuration.
[init -> tcp_terminal] using the lwIP libc plugin
[init -> nic_drv] no config provided, using tap0
[init -> tcp_terminal] Warning: '<config> <libc> <vfs/>' is deprecated, please move to '<config> <vfs/>'
[init -> tcp_terminal] --- TCP terminal started ---
[init] child "tcp_terminal" announces service "Terminal"
[init -> tcp_terminal] listening on port 8888 with socket 16...
[init -> tcp_terminal] adding listen sock 16 to select set

Though I can see the tap device,

15: tap0: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN mode DEFAULT group default qlen 1000
link/ether c2:60:31:f8:52:fc brd ff:ff:ff:ff:ff:ff

I don't see any listening socket on port 8888.

So clearly there is some missing plumbing. What do I need to do to
fill that in?

Thanks,

--prashanth

[Christian Helmuth]

Hello Prashanth,

Post by Prashanth Mundkur
After disabling the have_spec check, I can compile and run it. After
setting the suid bit on drivers/nic/spec/linux/nic_drv to allow it to

Just a remark to prevent setting suid: I setup my tap0 device so that
in can be used by my user ID like follows in /etc/rc.local on Ubuntu.

#
# Setup tap device for base-linux tests
#
dev=tap0
user=<YOUR USER ID>

ip tuntap add dev $dev mode tap user $user
ip address flush dev $dev
ip address add 10.0.2.1/24 brd 10.0.2.255 dev $dev
ip link set dev $dev addr 02:00:00:ca:fe:01
ip link set dev $dev up

But now to your question...

Post by Prashanth Mundkur
Though I can see the tap device,
15: tap0: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN mode DEFAULT group default qlen 1000
link/ether c2:60:31:f8:52:fc brd ff:ff:ff:ff:ff:ff
I don't see any listening socket on port 8888.
So clearly there is some missing plumbing. What do I need to do to
fill that in?

If you mean you can't see any listening program on port 8888 on your
host machine that's expected. Genode is running in a virtual network
behind the tap0 device. Additionally, the log states that the
tcp_terminal uses DHCP for network configuration but you may not run a
DHCP server on tap0. Now you have two option: Configure a DHCP server
to serve a private network behind tap, e.g., 10.0.2.1/24, or (much
simpler) configure tcp_terminal statically. Therefore you apply the
following changes to the run script (assuming the example network
above).

<start name="tcp_terminal">
- <libc stdout="/dev/log">
+ <libc ip_addr="10.0.2.55" netmask="255.255.255.0" gateway="10.0.2.1"
+ stdout="/dev/log" stderr="/dev/log"/>

The terminal should then be accessible at 10.0.2.55:8888.

Regards

[Prashanth Mundkur]

Post by Christian Helmuth
The terminal should then be accessible at 10.0.2.55:8888.

Wonderful, works perfectly. Thanks!