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# This test sets up a host-to-host IPsec VPN between Alice and Bob, each on its
# own network and with Eve as the only route between each other. We check that
# Eve can eavesdrop the plaintext traffic between Alice and Bob, but once they
# enable the secure tunnel Eve's spying becomes ineffective.
import ./make-test-python.nix ({ lib, pkgs, ... }:
let
# IPsec tunnel between Alice and Bob
tunnelConfig = {
services.libreswan.enable = true;
services.libreswan.connections.tunnel =
''
leftid=@alice
left=fd::a
rightid=@bob
right=fd::b
authby=secret
auto=add
'';
environment.etc."ipsec.d/tunnel.secrets" =
{ text = ''@alice @bob : PSK "j1JbIi9WY07rxwcNQ6nbyThKCf9DGxWOyokXIQcAQUnafsNTUJxfsxwk9WYK8fHj"'';
mode = "600";
};
};
# Common network setup
baseNetwork = {
# shared hosts file
extraHosts = lib.mkVMOverride ''
fd::a alice
fd::b bob
fd::e eve
'';
# remove all automatic addresses
useDHCP = false;
interfaces.eth1.ipv4.addresses = lib.mkVMOverride [];
interfaces.eth2.ipv4.addresses = lib.mkVMOverride [];
# open a port for testing
firewall.allowedUDPPorts = [ 1234 ];
};
# Adds an address and route from a to b via Eve
addRoute = a: b: {
interfaces.eth1.ipv6.addresses =
[ { address = a; prefixLength = 64; } ];
interfaces.eth1.ipv6.routes =
[ { address = b; prefixLength = 128; via = "fd::e"; } ];
};
in
{
name = "libreswan";
meta = with lib.maintainers; {
maintainers = [ rnhmjoj ];
};
# Our protagonist
nodes.alice = { ... }: {
virtualisation.vlans = [ 1 ];
networking = baseNetwork // addRoute "fd::a" "fd::b";
} // tunnelConfig;
# Her best friend
nodes.bob = { ... }: {
virtualisation.vlans = [ 2 ];
networking = baseNetwork // addRoute "fd::b" "fd::a";
} // tunnelConfig;
# The malicious network operator
nodes.eve = { ... }: {
virtualisation.vlans = [ 1 2 ];
networking = lib.mkMerge
[ baseNetwork
{ interfaces.br0.ipv6.addresses =
[ { address = "fd::e"; prefixLength = 64; } ];
bridges.br0.interfaces = [ "eth1" "eth2" ];
}
];
environment.systemPackages = [ pkgs.tcpdump ];
boot.kernel.sysctl."net.ipv6.conf.all.forwarding" = true;
};
testScript =
''
def alice_to_bob(msg: str):
"""
Sends a message as Alice to Bob
"""
bob.execute("nc -lu ::0 1234 >/tmp/msg &")
alice.sleep(1)
alice.succeed(f"echo '{msg}' | nc -uw 0 bob 1234")
bob.succeed(f"grep '{msg}' /tmp/msg")
def eavesdrop():
"""
Starts eavesdropping on Alice and Bob
"""
match = "src host alice and dst host bob"
eve.execute(f"tcpdump -i br0 -c 1 -Avv {match} >/tmp/log &")
start_all()
with subtest("Network is up"):
alice.wait_until_succeeds("ping -c1 bob")
with subtest("Eve can eavesdrop cleartext traffic"):
eavesdrop()
alice_to_bob("I secretly love turnip")
eve.sleep(1)
eve.succeed("grep turnip /tmp/log")
with subtest("Libreswan is ready"):
alice.wait_for_unit("ipsec")
bob.wait_for_unit("ipsec")
alice.succeed("ipsec verify 1>&2")
with subtest("Alice and Bob can start the tunnel"):
alice.execute("ipsec auto --start tunnel >&2 &")
bob.succeed("ipsec auto --start tunnel")
# apparently this is needed to "wake" the tunnel
bob.execute("ping -c1 alice")
with subtest("Eve no longer can eavesdrop"):
eavesdrop()
alice_to_bob("Just kidding, I actually like rhubarb")
eve.sleep(1)
eve.fail("grep rhubarb /tmp/log")
'';
})
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