How to connect guest from host in shared network mode?

[NanXiao]

Describe the issue
I am a newbie of Virtualisation, so very sorry for this naive question. I installed an OpenBSD VM, and the network mode is "shared network". The following is the ifconfig output from OpenBSD guest:

And from my host, I can find a new bridge100 NIC:

bridge100: flags=8a63<UP,BROADCAST,SMART,RUNNING,ALLMULTI,SIMPLEX,MULTICAST> mtu 1500
	options=3<RXCSUM,TXCSUM>
	ether 9e:3e:53:c6:52:64
	inet 192.168.64.1 netmask 0xffffff00 broadcast 192.168.64.255
	inet6 fe80::9c3e:53ff:fec6:5264%bridge100 prefixlen 64 scopeid 0x15
	inet6 fd47:e6a5:52a4:c3ca:1463:8bd1:b203:5aba prefixlen 64 autoconf secured
	Configuration:
		id 0:0:0:0:0:0 priority 0 hellotime 0 fwddelay 0
		maxage 0 holdcnt 0 proto stp maxaddr 100 timeout 1200
		root id 0:0:0:0:0:0 priority 0 ifcost 0 port 0
		ipfilter disabled flags 0x0
	member: vmenet0 flags=3<LEARNING,DISCOVER>
	        ifmaxaddr 0 port 20 priority 0 path cost 0
	nd6 options=201<PERFORMNUD,DAD>
	media: autoselect
	status: active

I tried to ping OpenBSD guest from host, but it failed:

$ ping 192.168.64.4
PING 192.168.64.4 (192.168.64.4): 56 data bytes
ping: sendto: No route to host
Request timeout for icmp_seq 0
ping: sendto: No route to host
Request timeout for icmp_seq 1

But ping bridge100 works:

$ ping 192.168.64.1
PING 192.168.64.1 (192.168.64.1): 56 data bytes
64 bytes from 192.168.64.1: icmp_seq=0 ttl=64 time=5.474 ms
64 bytes from 192.168.64.1: icmp_seq=1 ttl=64 time=0.400 ms 

So how should I connect to guest VM in shared network mode? Thanks very much in advance!

P.S., I read https://docs.getutm.app/settings-qemu/devices/network/network/#network-mode, but it seems there is no answer.
Configuration

• UTM Version: 4.6.5 (108)
• macOS Version: Darwin nanxiaos-MacBook-Pro.local 24.6.0 Darwin Kernel Version 24.6.0: Mon Jul 14 11:30:51 PDT 2025; root:xnu-11417.140.69~1/RELEASE_ARM64_T8112 arm64
• Mac Chip (Intel, M1, ...): M2

[osy]

Try bridged mode.

[NanXiao]

@osy After switching to bridged mode, no matter I tired Automatic NIC or en0, still can't accessed:

$ ping 192.168.1.11
PING 192.168.1.11 (192.168.1.11): 56 data bytes
ping: sendto: No route to host
Request timeout for icmp_seq 0
ping: sendto: No route to host
Request timeout for icmp_seq 1
^C

Compared to "shared" mode, there are some changes:
(1)The guest IP address is changed to 192.168.1.11.

(2) No IP address. for bridge100:

bridge100: flags=8863<UP,BROADCAST,SMART,RUNNING,SIMPLEX,MULTICAST> mtu 1500
	options=3<RXCSUM,TXCSUM>
	ether 9e:3e:53:c6:52:64
	Configuration:
		id 0:0:0:0:0:0 priority 0 hellotime 0 fwddelay 0
		maxage 0 holdcnt 0 proto stp maxaddr 100 timeout 1200
		root id 0:0:0:0:0:0 priority 0 ifcost 0 port 0
		ipfilter disabled flags 0x0
	member: en0 flags=8003<LEARNING,DISCOVER,MACNAT>
	        ifmaxaddr 0 port 11 priority 0 path cost 0
	member: vmenet0 flags=3<LEARNING,DISCOVER>
	        ifmaxaddr 0 port 20 priority 0 path cost 0
	nd6 options=201<PERFORMNUD,DAD>
	media: autoselect
	status: active

Thanks!

[osy]

Are you sure your VM isn't firewalled or rejecting ping? Does it work on any other vm?

[NanXiao]

@osy

Are you sure your VM isn't firewalled or rejecting ping? Does it work on any other vm?

I didn't set anything on my VMs. I freshly installed another FreeBSD VM, but same issue.

[osy]

But what if you use another OS like Ubuntu or Windows?

[NanXiao]

@osy Firstly, thanks very much for your time and response! I tried to install Ubuntu, but unfortunately the same result:
(1) The network configuration of guest:

(2) The IP address of guest is 192.168.64.7, and my host IP is 192.168.1.2. The guest can ping host successfully:

(3) But the host can't ping guest:

[BeniLeuz]

I had the exact same issue out of nowhere.
Via Iterm2 this didnt work. Via inbuilt terminal in macos it worked.
Therefore i came to the conclusion it was an issue on macos side somewhat permissions etc.

By enabling the permissions for iterm in privacy security => Local Network it worked.
I have no clue how this setting removed itself since it worked a week ago without changing anything.

[H4MST3R3N3RGYBALL]

@osy I am having the same issue on the latest UTM, but when I use shared networking it doesn't get an IP. This happens with any OS and all interfaces except emulated vlan but with that I can't connect or ping VM even with port forwarding enabled. I have tried Kali Linux x86 and ubuntu server x86. I am on M1 host.

[TrueBers]

Same for me. Windows 11 guest, MacOS 26.1 host. UTM 4.7.4 (115) just installed, settings are default. No route to host, but it seems to be fine:

   route to: 192.168.64.4
destination: 192.168.64.4
  interface: bridge100
      flags: <UP,HOST,DONE,LLINFO,WASCLONED,IFSCOPE,IFREF>
 recvpipe  sendpipe  ssthresh  rtt,msec    rttvar  hopcount      mtu     expire
       0         0         0         0         0         0      1500      1078

[alexeigs]

I can confirm a very consistent failure mode on macOS Sequoia that might explain several reports here.

On macOS 15.7.3 with UTM 4.7.4:

• Before starting any VM, there is no bridge100 interface or routing state.
• The moment a VM is started using Apple Virtualization + Shared Network, macOS installs RTF_REJECT routes on bridge100.
• Host → guest traffic is then rejected at the routing layer (not firewall), while guest → host still works.

Notably:

• This survives a full macOS reinstall.
• Local Network permissions never show UTM at all on this system (no toggle to enable).
• Standard fixes (firewall off, PF off, systemextensionsctl reset, etc.) don’t change the behavior.
• Switching the same VM disk to the QEMU backend avoids the issue entirely.

So this doesn’t look like a networking misconfiguration, but rather macOS policy rejecting host-initiated traffic on vmnet when Apple Virtualization is used.