Hi David,

Thank you for getting back to me. I have been trying to rehash some of the Arch documentation (https://wiki.archlinux.org/title/Libvirt), and I worked through parts of this tutorial for WinApps as another resource for configuring libvirt to run a Windows guest on a Linux host:

I think I found that the services for the libvirt daemon were not enabled. I also double checked that the user on the host has been added to the libvirt group.

One tidbit is that the host is connected to the internet via WiFi (wlp6s0), hence, the motivation to use passt in userspace mode. 

A couple of easy bits of information which might help:
  1. What's the passt version? (`passt --version` on the host)

passt 2025_09_11.6cbcccc

  2. What's the IP configuration within the Windows guest?

The windows guest:

Aggregated link speed (Receive/Transmit): 10/10 (Gbps)
IPv6 address: fdac:14bf:9c6f:942d:d4:e913:5731:9d0a
Link-local IPv6 address: fe80::5374:1174:7d88:4c94%12
IPv6 default gateway: fe80::11a9:af53:4e56:ea79%12
IPv4 address: 10.0.1.205
IPv4 DNS servers: 10.0.1.1 (Unencrypted)
8.8.8.8 (Unencrypted)
Manufacturer: Red Hat, Inc.
Description: Red Hat VirtIO Ethernet Adapter
Driver version: 100.101.104.28500
Physical address (MAC): 52:54:00:23:01:04

Notice that it matches wlp6s0 below due to the userspace mode config.

  3. What's the IP configuration on the host? (`ip addr show` and `ip route show`)

FYI, I have some docker containers running on the host as well. virbr0 is part of the virsh net. But in userspace mode with port forwarding, I shouldn't need an active bridge network for host-guest communication, correct?

$ ip addr show

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 noprefixroute
       valid_lft forever preferred_lft forever
2: enp7s0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc mq state DOWN group default qlen 1000
    link/ether 24:4b:fe:8e:01:eb brd ff:ff:ff:ff:ff:ff
    altname enx244bfe8e01eb
3: wlp6s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default qlen 1000
    link/ether 8c:c6:81:ce:46:0e brd ff:ff:ff:ff:ff:ff
    altname wlx8cc681ce460e
    inet 10.0.1.205/24 brd 10.0.1.255 scope global noprefixroute wlp6s0
       valid_lft forever preferred_lft forever
    inet6 fdac:14bf:9c6f:942d:2d42:74ac:5a3:58cd/64 scope global dynamic noprefixroute
       valid_lft 1726sec preferred_lft 1726sec
    inet6 fe80::11a9:af53:4e56:ea79/64 scope link noprefixroute
       valid_lft forever preferred_lft forever
4: virbr0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc noqueue state DOWN group default qlen 1000
    link/ether 52:54:00:dd:ac:d1 brd ff:ff:ff:ff:ff:ff
    inet 192.168.100.1/24 brd 192.168.100.255 scope global virbr0
       valid_lft forever preferred_lft forever
5: br-00cee4dd5f5b: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default
    link/ether 2e:72:a6:f4:0c:f0 brd ff:ff:ff:ff:ff:ff
    inet 172.16.0.1/16 brd 172.16.255.255 scope global br-00cee4dd5f5b
       valid_lft forever preferred_lft forever
    inet6 fe80::2c72:a6ff:fef4:cf0/64 scope link proto kernel_ll
       valid_lft forever preferred_lft forever
6: docker0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc noqueue state DOWN group default
    link/ether 2e:a1:03:c3:2e:e7 brd ff:ff:ff:ff:ff:ff
    inet 172.17.0.1/16 brd 172.17.255.255 scope global docker0
       valid_lft forever preferred_lft forever
7: br-3d69e1e5d7f4: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default
    link/ether 12:00:34:3b:5e:b7 brd ff:ff:ff:ff:ff:ff
    inet 172.18.0.1/16 brd 172.18.255.255 scope global br-3d69e1e5d7f4
       valid_lft forever preferred_lft forever
    inet6 fe80::1000:34ff:fe3b:5eb7/64 scope link proto kernel_ll
       valid_lft forever preferred_lft forever
8: br-48249c6f88eb: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default
    link/ether 96:1f:00:c2:00:e8 brd ff:ff:ff:ff:ff:ff
    inet 172.19.0.1/16 brd 172.19.255.255 scope global br-48249c6f88eb
       valid_lft forever preferred_lft forever
    inet6 fe80::941f:ff:fec2:e8/64 scope link proto kernel_ll
       valid_lft forever preferred_lft forever
9: veth6867d93@if2: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master br-3d69e1e5d7f4 state UP group default
    link/ether 12:1a:6b:c7:f0:16 brd ff:ff:ff:ff:ff:ff link-netnsid 0
    inet6 fe80::101a:6bff:fec7:f016/64 scope link proto kernel_ll
       valid_lft forever preferred_lft forever
10: veth69f97d5@if2: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master br-00cee4dd5f5b state UP group default
    link/ether 06:df:6a:4e:79:47 brd ff:ff:ff:ff:ff:ff link-netnsid 1
    inet6 fe80::4df:6aff:fe4e:7947/64 scope link proto kernel_ll
       valid_lft forever preferred_lft forever
11: veth1f70985@if2: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master br-48249c6f88eb state UP group default
    link/ether 42:06:3c:59:40:0e brd ff:ff:ff:ff:ff:ff link-netnsid 2
    inet6 fe80::4006:3cff:fe59:400e/64 scope link proto kernel_ll
       valid_lft forever preferred_lft forever
12: vethfccbd3e@if2: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master br-48249c6f88eb state UP group default
    link/ether a6:39:57:54:9e:5c brd ff:ff:ff:ff:ff:ff link-netnsid 3
    inet6 fe80::a439:57ff:fe54:9e5c/64 scope link proto kernel_ll
       valid_lft forever preferred_lft forever
13: vetha459fc8@if2: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master br-00cee4dd5f5b state UP group default
    link/ether 8a:4b:ce:31:c2:15 brd ff:ff:ff:ff:ff:ff link-netnsid 4
    inet6 fe80::884b:ceff:fe31:c215/64 scope link proto kernel_ll
       valid_lft forever preferred_lft forever
14: veth55aa848@if3: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master br-3d69e1e5d7f4 state UP group default
    link/ether d6:5c:de:ca:f4:6c brd ff:ff:ff:ff:ff:ff link-netnsid 1
    inet6 fe80::d45c:deff:feca:f46c/64 scope link proto kernel_ll
       valid_lft forever preferred_lft forever
15: veth97169d4@if3: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master br-48249c6f88eb state UP group default
    link/ether 0a:bb:8e:fd:a2:59 brd ff:ff:ff:ff:ff:ff link-netnsid 4
    inet6 fe80::8bb:8eff:fefd:a259/64 scope link proto kernel_ll
       valid_lft forever preferred_lft forever

$ ip route show

default via 10.0.1.1 dev wlp6s0 proto static metric 600
10.0.1.0/24 dev wlp6s0 proto kernel scope link src 10.0.1.205 metric 600
172.16.0.0/16 dev br-00cee4dd5f5b proto kernel scope link src 172.16.0.1
172.17.0.0/16 dev docker0 proto kernel scope link src 172.17.0.1 linkdown
172.18.0.0/16 dev br-3d69e1e5d7f4 proto kernel scope link src 172.18.0.1
172.19.0.0/16 dev br-48249c6f88eb proto kernel scope link src 172.19.0.1
192.168.100.0/24 dev virbr0 proto kernel scope link src 192.168.100.1 linkdown

  4. What's the output from `ssh -v`

$ ssh -vp 8022 127.0.0.1
debug1: OpenSSH_10.0p2, OpenSSL 3.5.3 16 Sep 2025
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: Reading configuration data /etc/ssh/ssh_config.d/20-systemd-ssh-proxy.conf
debug1: Reading configuration data /etc/ssh/ssh_config.d/30-libvirt-ssh-proxy.conf
debug1: Connecting to 127.0.0.1 [127.0.0.1] port 8022.
debug1: Connection established.
debug1: identity file 
. . .
debug1: identity file 
debug1: Local version string SSH-2.0-OpenSSH_10.0
kex_exchange_identification: read: Connection reset by peer
Connection reset by 127.0.0.1 port 8022

Best,

James