[SOLVED] No internet in Arch Linux ISO (installing on Hyper-V VM)

crimsoncandy · 2021-04-18 07:38:46

Hi, I am trying to install Arch Linux on Hyper-V Virtual Machine. My host machine has all incoming connections blocked by default, so internet doesn't work in archiso. I usually fix this on linux (previously I used WSL Debian) by changing dns server to google dns 8.8.8.8 using /etc/resolv.conf. But in this case of Arch Linux (or any linux distro) this fix does not work unless archiso is booted with incoming connections allowed. Although I do not know much about linux, here are some interesting findings.

When booted with all incoming connections blocked on host machine.

The output of ip route is empty.

Output of ip addr:

1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host
       valid_lft forever preferred_lft forever
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP group default qlen 1000
    link/ether 00:15:5d:fc:61:04 brd ff:ff:ff:ff:ff:ff
    inet6 fe80::215:5dff:fefc:6104/64 scope link
       valid_lft forever preferred_lft forever

When booted with incoming connections allowed but later blocked after boot.

The output of ip route is:

default via 172.19.16.1 dev eth0 proto dhcp src 172.19.25.176 metric 512
172.19.16.0/20 dev eth0 proto kernel scope link src 172.19.25.176
172.19.16.1 dev eth0 proto dhcp scope link src 172.19.25.176 metric 512

The output of ip addr is:

1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host
       valid_lft forever preferred_lft forever
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP group default qlen 1000
    link/ether 00:15:5d:fc:61:04 brd ff:ff:ff:ff:ff:ff
    inet 172.19.25.176/20 brd 172.19.31.255 scope global dynamic eth0
       valid_lft 85773sec preferred_lft 85773sec
    inet6 fe80::215:5dff:fefc:6104/64 scope link
       valid_lft forever preferred_lft forever

Here 172.19.16.1 is the IP address of Hyper-V Ethernet Adapter and 172.19.25.176 is IP address that I can use to SSH to VM (not possible in first scenario). Maybe if IP addresses on Linux guest are set manually it is possible to fix the problem but I'm not sure how to do it. That said I still don't know if it is the correct solution.

Last edited by crimsoncandy (2021-04-18 12:06:03)

crimsoncandy · 2021-04-18 09:03:20

I found that doing

ip addr add 172.19.25.176/20 dev eth0

and

ip route add default via 172.19.16.1 dev eth0 proto dhcp src 172.19.25.176

make internet work. But I'm still looking for better solution and to make changes permanent in final install.

tucuxi · 2021-04-18 10:02:52

It seems that the host does not provide any IP address to the guest via dhcp, possibly because incoming requests are blocked. Try unblocking connections from the guest or configure systemd-networkd to use a static address if you prefer that.

Last edited by tucuxi (2021-04-18 10:03:24)

ewaller · 2021-04-18 16:04:20

I am going to point you at https://wiki.archlinux.org/index.php/Ne … figuration

I found the systemd-nwtwork to work well for me. It can easily configure static IP addresses and routes for you and start them as a system service.

Arch Linux

#1 2021-04-18 07:38:46