ipv6 - What is ipv6proxy in android emulator used for?

Question

According to android source code for emualator (generic/goldfish), a native executable named ipv6proxy is provided for forwarding traffic between wlan1/radio0-peer and eth0.

The network architecture is described in device/generic/goldfish/wifi/init.wifi.sh at https://android-opengrok.bangnimang.net/android-9.0.0_r61/xref/device/generic/goldfish/wifi/init.wifi.sh?r=23c07326.

#          main namespace                     router namespace
#       -------       ----------   |    ---------------
#       | ril |<----->| radio0 |<--+--->| radio0-peer |<-------+
#       -------       ----------   |    ---------------        |
#                                  |            ^              |
#                                  |            |              |
#                                  |            v              v
#                                  |      *************     --------
#                                  |      * ipv6proxy *<--->| eth0 |<--+
#                                  |      *************     --------   |
#                                  |            ^              ^       |
#                                  |            |              |       |
#                                  |            v              |       |
# ------------------   ---------   |        ---------          |       |
# | wpa_supplicant |<->| wlan0 |<--+------->| wlan1 |<---------+       |
# ------------------   ---------   |        ---------                  |
#                                  |         ^     ^                   |
#                                  |         |     |                   v
#                                  |         v     v                --------
#                                  | ***********  ***********       | host |
#                                  | * hostapd *  * dnsmasq *       --------
#                                  | ***********  ***********

According to this script, the ipv4 traffic is NAT forwarded by iptables, but ipv6 is forwarded by ipv6proxy in userspace.

Why?

The module ipv6proxy is located at https://android-opengrok.bangnimang.net/android-9.0.0_r61/xref/device/generic/goldfish/wifi/ipv6proxy/. Command line to start it is ipv6proxy -o eth0 -i wlan1,radio0-peer.

question from:https://stackoverflow.com/questions/65878681/what-is-ipv6proxy-in-android-emulator-used-for

Answer 1

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