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Routing tips for VPNs on OS X

When VPNs Just Work™, they're a fantastic way of allowing access to a private network from remote locations. When they don't work it can be an experience in frustration. I've had situations where I can connect to a VPN from my Mac, but various networking situations cause routing conflicts. Here are a couple of cases and how I've been able to get around them.

Specific cases

Case 1: conflicting additional routes.

In this example the VPN we are connecting to has a subnet that does not conflict with our local IP, but has additional routes that conflict in some way with our local network's routing. In my example the remote subnet is 10.0.x.0/24, my local subnet is 10.0.y.0/24, and the conflicting route is 10.0.0.0/8. Without the later route, I can't access all hosts on the VPN without manually adding the route after connecting to the VPN:

	import os
	import sys

	import torch._dynamo.compiled_autograd

	with open(sys.argv[0]) as f:
	code = f.read() # read the code of this file ASAP, for logging
	import uuid
	import glob
	import time

	import torch
	import torch.utils.benchmark as benchmark


	def benchmark_in_us(f, args, *kwargs):
	t0 = benchmark.Timer(
	stmt="f(args, *kwargs)", globals={"args": args, "kwargs": kwargs, "f": f}
	)
	return t0.blocked_autorange().mean * 1e6

	import torch
	from torch.distributed.device_mesh import init_device_mesh
	from torch.distributed.tensor import DTensor, Shard

	mesh_1d = init_device_mesh("cuda", (4,), mesh_dim_names=("shard",))

	rank = mesh_1d.get_rank()

	dtensors: list[DTensor] = []

	import os
	from typing import cast

	import torch
	import torch._inductor.config as config
	import torch.distributed as dist


	def zeropower_via_newtonschulz5(G, steps=10, eps=1e-7) -> torch.Tensor: ...

	import os
	import base64


	# dynamically generated at test time
	A_identifier = base64.urlsafe_b64encode(os.urandom(6)).decode()
	B_identifier = base64.urlsafe_b64encode(os.urandom(6)).decode()


	meta_prompt = f"""

	from dataclasses import dataclass


	class Default(dict[str, str]):
	def __missing__(self, key: str):
	return f"{{{key}}}"


	@dataclass
	class Pair:

	INFO global: Vagrant version: 2.3.3
	INFO global: Ruby version: 2.7.6
	INFO global: RubyGems version: 3.1.6
	INFO global: VAGRANT_EXECUTABLE="C:\\HashiCorp\\Vagrant\\embedded\\gems\\2.3.3\\gems\\vagrant-2.3.3\\bin\\vagrant"
	INFO global: VAGRANT_INSTALLER_EMBEDDED_DIR="C:\\HashiCorp\\Vagrant\\embedded"
	INFO global: VAGRANT_INSTALLER_ENV="1"
	INFO global: VAGRANT_INSTALLER_VERSION="2"
	INFO global: VAGRANT_LOG="debug"
	WARN global: resolv replacement has not been enabled!
	DEBUG global: Loading core plugin: C:/HashiCorp/Vagrant/embedded/gems/2.3.3/gems/vagrant-2.3.3/plugins/commands/autocomplete/plugi