LinuxQuestions.org - Internet sharing from ppp0 to uap0 [Hotspot] in linux based embedded board

- Linux - Networking (https://www.linuxquestions.org/questions/linux-networking-3/)

- - Internet sharing from ppp0 to uap0 [Hotspot] in linux based embedded board (https://www.linuxquestions.org/questions/linux-networking-3/internet-sharing-from-ppp0-to-uap0-%5Bhotspot%5D-in-linux-based-embedded-board-4175662960/)

Internet sharing from ppp0 to uap0 [Hotspot] in linux based embedded board

Hi,

I am working on a task ,internet sharing between two interfaces ppp0 and uap0 which is the hotspot interface .

ppp0 gets internet connection . I am able to ping google. And the IP here keeps on changing

uap0 is the interface which is used for hotspot connection of the board. I have set an IP of 192.168.10.1 to this interface and runs an dhcp server. My phone gets connected to the board via uap0 and gets an IP of 192.168.10.2

I am expecting an internet connection in my phone. But it is not happening

internet <-----> ppp0 <-----> uap0 <-----> phone

Once both the interfaces are up , my routing table is something like this

Code:

  Kernel IP routing table

  Destination    Gateway        Genmask        Flags Metric Ref    Use Iface



  0.0.0.0        0.0.0.0        0.0.0.0        U    0      0        0 ppp0



  192.168.10.0    0.0.0.0        255.255.255.0  U    0      0        0 uap0

And I tried below iptable rules

Code:

 echo 0 > /proc/sys/net/ipv4/ip_forward

iptables -P INPUT ACCEPT

iptables -P OUTPUT ACCEPT

iptables -t nat -I PREROUTING -i ppp0 -j DNAT --to-destination 192.168.10.0

iptables  -A FORWARD -m state --state ESTABLISHED -j ACCEPT

iptables -A FORWARD -t filter -i ppp0 -o uap0 -s 10.212.17.0 -p tcp --dport 8

iptables -A FORWARD -t filter -i uap0 -o ppp0 -d 192.168.10.0 -p tcp --sport 80

iptables -t nat -A POSTROUTING -o ppp0 -s 192.168.10.0/24 -j SNAT --to-source 10.212.17.0

echo 1 > /proc/sys/net/ipv4/ip_forward

When I checked whether iptable rules are getting hit, there are no forward packets getting incremented

Whether the iptable rules are proper.? Or should I make any changed to the routing table. I am a newbie to
iptables and NAT related concepts.

Any help would be appreciated.

ppp0 needs to forward it's own traffic to the internet, and I gather that's happening.

uap0 needs to forward everything to ppp0. Is that happening? are uap0 & ppp0 on the same box?

uap0 also needs to run a dhcp server. The kernel may need to have ipv4 forwarding enabled.

Now I don't wan to do your homework for you. So in the words of Jean-Luc Picard: "Makeit So!"

Thanks for the reply.

-> uap0 needs to forward everything to ppp0. Is that happening? are uap0 & ppp0 on the same box?

uap0 and ppp0 belongs to a single board. From the output of "watch -n1 iptables -vL", the forward packets count is zero. So I concluded the forwarding is not happening.

-> uap0 also needs to run a dhcp server. The kernel may need to have ipv4 forwarding enabled.

Hi ,

Thanks for the reply.

-> ppp0 needs to forward it's own traffic to the internet, and I gather that's happening.

Yup. This is happening.

-> uap0 needs to forward everything to ppp0. Is that happening? are uap0 & ppp0 on the same box?

From the output of "watch -n1 iptables -vL I can see no increment in number of packets forwarded . I believe,packet forwarding is something that need attention
uap0 and ppp0 belong to same board

->uap0 also needs to run a dhcp server. The kernel may need to have ipv4 forwarding enabled.

uap0 has a dhcp server running. Also I have enabled the ipv4 forwarding using "echo 1 > /proc/sys/net/ipv4/ip_forward" . And routing related macros in Kernel are enabled and rechecked. I wonder is there anything else which contribute to ip forwarding and that exactly I am missing

A few things can hold you up.

Off the top of my head

Your kernel routing table. uap0 needs to funnel stuff to ppp0. ppp0 needs to see the outside world. Programs are inclined to hack this every time, so be careful.
Your dhcp server needs to have and forward dns server numbers to everything that signs on unless you're also running a dns server.