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- <title>Re: GSoC Port Forwarding</title>
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- <table border=0 cellspacing=0 cellpadding=0 width="100%" class="header-part1"><tr><td><div class="headerdisplayname" style="display:inline;">Oggetto: </div>Re: GSoC Port Forwarding</td></tr><tr><td><div class="headerdisplayname" style="display:inline;">Mittente: </div>Giulio <giulio@gmx.com></td></tr><tr><td><div class="headerdisplayname" style="display:inline;">Data: </div>15/08/2021, 17:35</td></tr></table><table border=0 cellspacing=0 cellpadding=0 width="100%" class="header-part2"><tr><td><div class="headerdisplayname" style="display:inline;">A: </div>Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com></td></tr><tr><td><div class="headerdisplayname" style="display:inline;">CC: </div>Frédéric Pierret <frederic.pierret@qubes-os.org></td></tr></table><br>
- <div class="moz-text-flowed" style="font-family: -moz-fixed; font-size: 14px;" lang="x-unicode">Hello,
- <br>Thank you for you fast reply.
- <br>
- <br>Il 14/08/2021 23:43, Marek Marczykowski-Górecki ha scritto:
- <br><blockquote type=cite style="color: #007cff;">
- <br>As for the nft syntax, I think iptables-translate tool can help you
- <br>(part of the iptables-nft package).
- <br>See <a class="moz-txt-link-freetext" href="https://wiki.nftables.org/wiki-nftables/index.php/Moving_from_iptables_to_nftables">https://wiki.nftables.org/wiki-nftables/index.php/Moving_from_iptables_to_nftables</a>
- <br>
- <br><blockquote type=cite style="color: #007cff;">You can see in [4] how I organized the forwarding mechanism. All the
- <br>necessary information, as well as ipv4/ipv6 support should already be in
- <br>the 'prepare_forward_rules' function meaning that only the actual
- <br>building syntax is left.
- <br></blockquote>
- <br></blockquote>
- <br>I have tried to write the external nft rules as well the extarnal ones,
- with the exception of the destination domain.
- <br>
- <br>Assume the following setup:
- <br>sys-net - 10.137.0.5 (ens6 phy with 192.168.10.20)
- <br>sys-firewall - 10.137.0.6
- <br>personal - 10.137.0.7
- <br>
- <br>All of them are running fedora-32.
- <br>
- <br>And assume the following rule added via qvm-firewall:
- <br># qvm-firewall personal add action=forward forwardtype=external
- scrports=22-22 proto=tcp dstports=2222-2222 srchost=192.168.10.0/24
- <br>.
- <br>First, a table for the forwarding rules is created:
- <br>
- <br>flush chain {family} qubes-firewall-forward prerouting
- <br>flush chain {family} qubes-firewall-forward postrouting
- <br>table {family} qubes-firewall-forward {
- <br> chain postrouting {
- <br> type nat hook postrouting priority srcnat; policy accept;
- <br> masquerade
- <br> }
- <br> chain prerouting {
- <br> type nat hook prerouting priority dstnat; policy accept;
- <br> }
- <br>}
- <br>
- <br>Then, if the qube is marked as 'last', meaning that it is the external
- qube with the physical interface the following rules are added:
- <br>
- <br>table {family} qubes-firewall-forward {
- <br> chain prerouting {
- <br> meta iifname "ens6" {family} saddr 192.168.10.0/24 tcp dport {{ 22 }}
- dnat to 10.137.0.6:2222
- <br> }
- <br>}
- <br>
- <br>table {family} qubes-firewall {
- <br> chain forward {
- <br> meta iifname "eth0" {family} daddr 10.137.0.6 tcp dport 2222 ct state
- new counter accept
- <br> }
- <br>}
- <br>
- <br>And that is all for sys-net.
- <br>
- <br>In sys-firewall, since it is an 'internal' qube, the following rules are
- added instead:
- <br>
- <br>table {family} qubes-firewall-forward {
- <br> chain prerouting {
- <br> meta iifname "eth0" {family} saddr 120.137.0.5 tcp dport {{ 2222 }}
- dnat to 10.137.0.7:2222
- <br> }
- <br>}
- <br>
- <br>table {family} qubes-firewall {
- <br> chain forward {
- <br> meta iifname "eth0" {family} daddr 10.137.0.7 tcp dport 2222 ct state
- new counter accept
- <br> }
- <br>}
- <br>
- <br>Lastly, the appropriate rules allowing incoming traffic on the selected
- port from the previous hop should be added directly yo the 'personal'
- domain. However I see that there the nft ruleset is empty, while
- iptables seems indeed to be in use. I guess that those rules are the
- ones specified in qubes-core-agent-linux/network/iptables, however I am
- wondering how we should proceed on this one?
- <br>
- <br>Also are you able to spot errors or something missing in the
- aforedescribed rule flow? When testing I can see the incoming connection
- on port 22 of the physical interface of sys-net, but then I am losing
- track of the connection after that...
- <br>
- <br>
- <br><blockquote type=cite style="color: #007cff;">In both cases, the code will need some tests of course.
- <br>
- <br></blockquote>
- <br>As soon as everything seems to work with my manual test, I will start
- progressively writing the automated tests.
- <br>
- <br>Cheers
- <br>Giulio
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