* Add a module for doing Network Address Translation.

svn path=/nixos/trunk/; revision=26246
This commit is contained in:
Eelco Dolstra 2011-03-10 12:08:39 +00:00
parent e2e7b689b4
commit 9bf4ac079e
3 changed files with 115 additions and 14 deletions

View file

@ -99,6 +99,7 @@
./services/networking/gw6c.nix
./services/networking/ifplugd.nix
./services/networking/ircd-hybrid.nix
./services/networking/nat.nix
./services/networking/ntpd.nix
./services/networking/openfire.nix
./services/networking/openvpn.nix

View file

@ -0,0 +1,95 @@
# This module enables Network Address Translation (NAT).
{ config, pkgs, ... }:
with pkgs.lib;
let
cfg = config.networking.nat;
in
{
###### interface
options = {
networking.nat.enable = mkOption {
default = false;
description =
''
Whether to enable Network Address Translation (NAT).
'';
};
networking.nat.internalIPs = mkOption {
example = "192.168.1.0/24";
description =
''
The IP address range for which to perform NAT. Packets
coming from these addresses and destined for the external
interface will be rewritten.
'';
};
networking.nat.externalInterface = mkOption {
example = "eth1";
description =
''
The name of the external network interface.
'';
};
networking.nat.externalIP = mkOption {
default = "";
example = "203.0.113.123";
description =
''
The public IP address to which packets from the local
network are to be rewritten. If this is left empty, the
IP address associated with the external interface will be
used.
'';
};
};
###### implementation
config = mkIf config.networking.nat.enable {
environment.systemPackages = [ pkgs.iptables ];
jobs.nat =
{ description = "Network Address Translation";
startOn = "started network-interfaces";
path = [ pkgs.iptables ];
preStart =
''
iptables -t nat -F
iptables -t nat -X
iptables -t nat -A POSTROUTING \
-s ${cfg.internalIPs} -o ${cfg.externalInterface} \
${if cfg.externalIP == ""
then "-j MASQUERADE"
else "-j SNAT --to-source ${cfg.externalIP}"}
echo 1 > /proc/sys/net/ipv4/ip_forward
'';
postStop =
''
iptables -t nat -F
'';
};
};
}

View file

@ -19,7 +19,9 @@
router =
{ config, pkgs, ... }:
{ virtualisation.vlans = [ 2 1 ];
environment.systemPackages = [ pkgs.iptables ];
networking.nat.enable = true;
networking.nat.internalIPs = "192.168.1.0/24";
networking.nat.externalInterface = "eth1";
};
server =
@ -37,22 +39,25 @@
# The router should have access to the server.
$server->waitForJob("httpd");
$router->mustSucceed("curl --fail http://server/ >&2");
$router->succeed("curl --fail http://server/ >&2");
# But the client shouldn't be able to reach the server.
$client->mustFail("curl --fail --connect-timeout 5 http://server/ >&2");
# The client should be also able to connect via the NAT router.
$router->waitForJob("nat");
$client->succeed("curl --fail http://server/ >&2");
$client->succeed("ping -c 1 server >&2");
# If we turn off NAT, the client shouldn't be able to reach the server.
$router->succeed("stop nat");
$client->fail("curl --fail --connect-timeout 5 http://server/ >&2");
$client->fail("ping -c 1 server >&2");
# Enable NAT on the router.
$router->mustSucceed(
"iptables -t nat -F",
"iptables -t nat -A POSTROUTING -s 192.168.1.0/24 -d 192.168.1.0/24 -j ACCEPT",
"iptables -t nat -A POSTROUTING -s 192.168.1.0/24 -j SNAT "
. "--to-source ${nodes.router.config.networking.ifaces.eth1.ipAddress}",
"echo 1 > /proc/sys/net/ipv4/ip_forward"
);
# And make sure that restarting the NAT job works.
$router->succeed("start nat");
$client->succeed("curl --fail http://server/ >&2");
$client->succeed("ping -c 1 server >&2");
# Now the client should be able to connect.
$client->mustSucceed("curl --fail http://server/ >&2");
$client->succeed("ping -c 1 router >&2");
$router->succeed("ping -c 1 client >&2");
'';
}