EDIT: The bad solution is to unblock UDP port 5353 but the port has to be source port, not destination port. (--sport flag) See the now modified rules. The issue is that this is very insecure (see this stackexchange question and comments) but obviously better than no firewall at all because at least I'm blocking TCP traffic.
The proper solution (other than using glibc and installing nss-mdns package) is to open a port with netcat (nc) in the background (using &) and then listen with dig on that port using the -b flag.
port="42069"
nc -l -p "$port" > /dev/null || exit 1 &
dig somehostname.local @224.0.0.241 -p 5353 -b "0.0.0.0#${port}"
Then we need to remember to kill the background process. The DNS reply will now be sent to port 42069, so we can just open it with this iptables rule:
-A INPUT -p udp -m udp --dport 42069 -j ACCEPT
---->END OF EDIT.
I want to setup iptables firewall but if I do that, it blocks multicast DNS which I need. I am using command
dig "somehostname.local" @224.0.0.251 -p 5353
to get the IP through mDNS and these are my iptables rules (from superuser.com):
*filter
# drop forwarded traffic. you only need it of you are running a router
:FORWARD DROP [0:0]
# Accept all outgoing traffic
:OUTPUT ACCEPT [623107326:1392470726908]
# Block all incoming traffic, all protocols (tcp, udp, icmp, ...) everything.
# This is the base rule we can define exceptions from.
:INPUT DROP [11486:513044]
# do not block already running connections (important for outgoing)
-A INPUT -m state --state RELATED,ESTABLISHED -j ACCEPT
# do not block localhost
-A INPUT -i lo -j ACCEPT
# do not block icmp for ping and network diagnostics. Remove if you do not want this
# note that -p icmp has no effect on ipv6, so we need an extra ipv6 rule
-4 -A INPUT -p icmp -j ACCEPT
-6 -A INPUT -p ipv6-icmp -j ACCEPT
# allow some incoming ports for services that should be public available
# -A INPUT -p tcp -m tcp --dport 22 -j ACCEPT
# -A INPUT -p udp -m udp --dport 5353 -j ACCEPT # does not help
-A OUTPUT -p udp -m udp --sport 5353 -j ACCEPT # SOLVES THE ISSUE BUT IS INSECURE - not recommended
# commit changes
COMMIT
Any help is welcome :)
CLA is basically a requirement for any larger scale open source project. It would be mental to add a "this single edited line is licensed under X license" to every tiny commit. Microsoft's CLA does not tranfer rights btw, it just licenses your contribution to M$ under "basically BSD 0 clause license" terms.
I guess sure they could do a ragpull but it does not make much sense. Reasons:
they have open sourced it themselves
It's made by M$ for M$. They don't have competition in the Windows space, so there is no point to hide the code.
Also what would be the worst thing that could happen if they did that? You would either use a fork, because WSL2 is basically feature complete at this points, or you would be have to use a proprietary app on a proprietary OS. Imo the licensing of WSL specifically is the least of Windows' issues.