port.md

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title: Port Forwarding
weight: 31

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Lima supports automatic port-forwarding of localhost ports from guest to host.

Port forwarding types

Lima supports two port forwarders: SSH and GRPC.

The default port forwarder is shown in the following table.

Version	Default
v0.1.0	SSH
v1.0.0	GRPC
v1.0.1	SSH
v1.1.0	GRPC

The default was once changed to GRPC in Lima v1.0, but it was reverted to SSH in v1.0.1 due to stability reasons. The default was further reverted to GRPC in Lima v1.1, as the stability issues were resolved.

Using SSH

SSH based port forwarding was previously the default mode.

To explicitly use SSH forwarding use the below command

LIMA_SSH_PORT_FORWARDER=true limactl start

Advantages

• Outperforms GRPC when VSOCK is available

Caveats

• Doesn't support UDP based port forwarding

• Spawns child process on host for running SSH master.

SSH over AF_VSOCK

⚡ Requirement	Lima >= 2.0

If VM is VZ based and systemd is v256 or later (e.g. Ubuntu 24.10+), Lima uses AF_VSOCK for communication between host and guest. SSH based port forwarding is much faster when using AF_VSOCK compared to traditional virtual network based port forwarding.

To disable this feature, set .ssh.overVsock to false:

limactl start --set '.ssh.overVsock=false'

Using GRPC

⚡ Requirement	Lima >= 1.0

In this model, lima uses existing GRPC communication (Host <-> Guest) to tunnel port forwarding requests. For each port forwarding request, a GRPC tunnel is created and this will be used for transmitting data

To enable this feature, set LIMA_SSH_PORT_FORWARDER to false:

LIMA_SSH_PORT_FORWARDER=false limactl start

Advantages

• Supports both TCP and UDP based port forwarding

• Performs faster compared to SSH based forwarding, when VSOCK is not available

• No additional child process for port forwarding

Accessing ports by IP address

To access a guest's ports by its IP address, connect the guest to the vzNAT or the lima:shared network.

The vzNAT network is extremely faster and easier to use, however, vzNAT is only available for VZ guests.

limactl start --network vzNAT
lima ip addr show lima0

See Config » Network » VMNet networks for the further information.

Benchmarks

By localhost	SSH (w/o VSOCK)	GRPC	SSH (w/ VSOCK)
TCP	4.06 Gbits/sec	5.37 Gbits/sec	6.32 Gbits/sec
TCP Reverse	3.84 Gbits/sec	7.11 Gbits/sec	7.47 Gbits/sec

By IP address	lima:shared	vzNAT
TCP	3.46 Gbits/sec	59.2 Gbits/sec
TCP Reverse	2.35 Gbits/sec	130 Gbits/sec

The benchmarks detail above are obtained using the following commands

Host -> limactl start vz

VZ Guest -> iperf3 -s

Host -> iperf3 -c 127.0.0.1 //Benchmark for TCP (average of "sender" and "receiver")
Host -> iperf3 -c 127.0.0.1 -R //Benchmark for TCP Reverse (same as above)

The benchmark result, especially the throughput of vzNAT, highly depends on the performance of the hardware.

Benchmarking environment

• Lima version: 2.0.0-alpha.2

• Guest: Ubuntu 25.04

  • OpenSSH 9.9p1

  • iperf 3.18

• Host: macOS 26.0.1

  • OpenSSH 10.0p2

  • iperf 3.19.1 (Homebrew)

• Hardware: MacBook Pro 2024 (M4 Max, 128 GiB)