The answer depends on what you mean by “in Qubes”.
Remember that each qube (or virtual machine) has its own operating system and is isolated from the other.
Some qubes that are created during a default Qubes OS installation have iptables installed.
For example, running which iptables in sys-firewall should print something. (The location of iptables.)
When it comes to proxy-vm, it really depends on how you created it. From the output you provided in your post, it seems like installing iptables wasn’t part of the steps you took when creating the qube, or maybe you missed that step. I would expext that running which iptables in your proxy-vm would currently print nothing.
If you want iptables to be available in proxy-vm I would suggest:
verifying that you didn’t miss a step in the instructions that you followed to create it
then installing it, as you would install any other program (docs)
After installing iptables, you can verify that it is indeed available by verifying that running which iptables in your proxy-vm prints something.
The answer is “Yes, iptables is already installed in Qubes”
That is, it is installed by default in the main Fedora and Debian templates.
You don’t say how you created your Proxy - if it is based on a minimal
template, then iptables will have been pulled in when you installed qubes-core-agent-networking
As @disp6252 points out, you need root access - either calling it with sudo iptables.. , opening a root terminal, or getting root using sudo su
There’s another sense of the question - Shouldiptables be
installed in Qubes?.
I feel the answer to this should be “No”, and there is active work to
remove the old iptables code from Qubes.
iptables is old and deprecated: it has been replaced by nftables.
When you use iptables in Qubes, you are using a compatibility layer
that uses the old iptables pattern syntax and the new nftables kernel
API. You can confirm this with iptables -V which should show iptables..(nf_tables)
This has the advantage that you can use iptables commands and the
rules will be available in nft list.
At some point users will have to transition to using nft - I suggest
they start now.
I never presume to speak for the Qubes team.
When I comment in the Forum or in the mailing lists I speak for myself.
Silence usually means success on the Linux command line @tree!
Unless you specifically expect the command you run to print something, the fact that you see a new command prompt usually means everything went right and the terminal is ready to receive your next command.
Without being familiar with iptables, I’m pretty sure that’s what you’re seeing here. Others will be able to confirm.