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 is the legacy mode that was previously default.

To explicitly use SSH forwarding use the below command

LIMA_SSH_PORT_FORWARDER=true limactl start

Caveats

• Doesn't support UDP based port forwarding

• Spawns child process on host for running SSH master.

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

• No additional child process for port forwarding

Benchmarks

Use case	GRPC	SSH
TCP	3.80 Gbits/sec	3.38 Gbits/sec
TCP Reverse	4.77 Gbits/sec	3.08 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 
Host -> iperf3 -c 127.0.0.1 -R //Benchmark for TCP Reverse