Port Forwarding

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

Port forwarding types

Lima supports the following port forwarders:

• Dual (SSH for TCP, GRPC for UDP)
• SSH
• GRPC

The default port forwarder is shown in the following table.

Using Dual forwarder

The dual forwarder uses SSH for TCP and GRPC for UDP to mix the advantages of the both forwarders.

portForwardTypes:
  tcp: ssh
  udp: grpc

This is the default mode since Lima v2.0.

Using SSH

SSH-only port forwarding was previously the default mode.

• Lima v2.0+
• Lima v1.x

portForwardTypes:
  tcp: ssh
  udp: none

# Deprecated
export 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

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 LIMA_SSH_OVER_VSOCK to false:

export LIMA_SSH_OVER_VSOCK=false

Using GRPC

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

• Lima v2.0+
• Lima v1.x

portForwardTypes:
  any: grpc

# Deprecated
export 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

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.