Using VPP as a Home Gateway

Vpp running on a small system (with appropriate NICs) makes a fine home gateway. The resulting system performs far in excess of requirements: a TAG=vpp_debug image runs at a vector size of ~1.1 terminating a 90-mbit down / 10-mbit up cable modem connection.

At a minimum, install sshd and the isc-dhcp-server. If you prefer, you can use dnsmasq.

Configuration files

/etc/vpp/startup.conf:

unix {
  nodaemon
  log /var/log/vpp/vpp.log
  full-coredump
  cli-listen /run/vpp/cli.sock
  startup-config /setup.gate
  gid vpp
}
api-segment {
  gid vpp
}
dpdk {
     dev 0000:03:00.0
     dev 0000:14:00.0
     etc.
     poll-sleep 10
}

isc-dhcp-server configuration:

subnet 192.168.1.0 netmask 255.255.255.0 {
  range 192.168.1.10 192.168.1.99;
  option routers 192.168.1.1;
  option domain-name-servers 8.8.8.8;
}

If you decide to enable the vpp dns name resolver, substitute 192.168.1.2 for 8.8.8.8 in the dhcp server configuration.

/etc/ssh/sshd_config:

# What ports, IPs and protocols we listen for
Port <REDACTED-high-number-port>
# Change to no to disable tunnelled clear text passwords
PasswordAuthentication no

For your own comfort and safety, do NOT allow password authentication and do not answer ssh requests on port 22. Experience shows several hack attempts per hour on port 22, but none (ever) on random high-number ports.

vpp configuration:

comment { This is the WAN interface }
set int state GigabitEthernet3/0/0 up
comment { set int mac address GigabitEthernet3/0/0 mac-to-clone-if-needed }
set dhcp client intfc GigabitEthernet3/0/0 hostname vppgate

comment { Create a BVI loopback interface}
loop create
set int l2 bridge loop0 1 bvi
set int ip address loop0 192.168.1.1/24
set int state loop0 up

comment { Add more inside interfaces as needed ... }
set int l2 bridge GigabitEthernet0/14/0 1
set int state GigabitEthernet0/14/0 up

comment { dhcp server and host-stack access }
tap connect lstack address 192.168.1.2/24
set int l2 bridge tapcli-0 1
set int state tapcli-0 up

comment { Configure NAT}
nat44 add interface address GigabitEthernet3/0/0
set interface nat44 in loop0 out GigabitEthernet3/0/0

comment { allow inbound ssh to the <REDACTED-high-number-port>
nat44 add static mapping local 192.168.1.2 <REDACTED> external GigabitEthernet3/0/0 <REDACTED> tcp

comment { if you want to use the vpp DNS server, add the following }
comment { Remember to adjust the isc-dhcp-server configuration appropriately }
comment { nat44 add identity mapping external GigabitEthernet3/0/0 udp 53053  }
comment { bin dns_name_server_add_del 8.8.8.8 }
comment { bin dns_name_server_add_del 68.87.74.166 }
comment { bin dns_enable_disable }
comment { see patch below, which adds these commands }
service restart isc-dhcp-server
add default linux route via 192.168.1.1

Patches

You’ll need this patch to add the “service restart” and “add default linux route” commands:

diff --git a/src/vpp/vnet/main.c b/src/vpp/vnet/main.c
index 6e136e19..69189c93 100644
--- a/src/vpp/vnet/main.c
+++ b/src/vpp/vnet/main.c
@@ -18,6 +18,8 @@
 #include <vlib/unix/unix.h>
 #include <vnet/plugin/plugin.h>
 #include <vnet/ethernet/ethernet.h>
+#include <vnet/ip/ip4_packet.h>
+#include <vnet/ip/format.h>
 #include <vpp/app/version.h>
 #include <vpp/api/vpe_msg_enum.h>
 #include <limits.h>
@@ -400,6 +402,63 @@ VLIB_CLI_COMMAND (test_crash_command, static) = {

 #endif

+static clib_error_t *
+restart_isc_dhcp_server_command_fn (vlib_main_t * vm,
+                                    unformat_input_t * input,
+                                    vlib_cli_command_t * cmd)
+{
+  int rv __attribute__((unused));
+  /* Wait three seconds... */
+  vlib_process_suspend (vm, 3.0);
+
+  rv = system ("/usr/sbin/service isc-dhcp-server restart");
+
+  vlib_cli_output (vm, "Restarted the isc-dhcp-server...");
+  return 0;
+}
+
+/* *INDENT-OFF* */
+VLIB_CLI_COMMAND (restart_isc_dhcp_server_command, static) = {
+  .path = "service restart isc-dhcp-server",
+  .short_help = "restarts the isc-dhcp-server",
+  .function = restart_isc_dhcp_server_command_fn,
+};
+/* *INDENT-ON* */
+
+static clib_error_t *
+add_default_linux_route_command_fn (vlib_main_t * vm,
+                                    unformat_input_t * input,
+                                    vlib_cli_command_t * c)
+{
+  int rv __attribute__((unused));
+  ip4_address_t ip4_addr;
+  u8 *cmd;
+
+  if (!unformat (input, "%U", unformat_ip4_address, &ip4_addr))
+    return clib_error_return (0, "default gateway address required...");
+
+  cmd = format (0, "/sbin/route add -net 0.0.0.0/0 gw %U",
+                format_ip4_address, &ip4_addr);
+  vec_add1 (cmd, 0);
+
+  rv = system (cmd);
+
+  vlib_cli_output (vm, "%s", cmd);
+
+  vec_free(cmd);
+
+  return 0;
+}
+
+/* *INDENT-OFF* */
+VLIB_CLI_COMMAND (add_default_linux_route_command, static) = {
+  .path = "add default linux route via",
+  .short_help = "Adds default linux route: 0.0.0.0/0 via <addr>",
+  .function = add_default_linux_route_command_fn,
+};
+/* *INDENT-ON* */
+
+

Using the temporal mac filter plugin

If you need to restrict network access for certain devices to specific daily time ranges, configure the “mactime” plugin. Enable the feature on the NAT “inside” interfaces:

bin mactime_enable_disable GigabitEthernet0/14/0
bin mactime_enable_disable GigabitEthernet0/14/1
...

Create the required src-mac-address rule database. There are 4 rule entry types:

  • allow-static - pass traffic from this mac address
  • drop-static - drop traffic from this mac address
  • allow-range - pass traffic from this mac address at specific times
  • drop-range - drop traffic from this mac address at specific times

Here are some examples:

bin mactime_add_del_range name alarm-system mac 00:de:ad:be:ef:00 allow-static
bin mactime_add_del_range name unwelcome mac 00:de:ad:be:ef:01 drop-static
bin mactime_add_del_range name not-during-business-hours mac <mac> drop-range Mon - Fri 7:59 - 18:01
bin mactime_add_del_range name monday-busines-hours mac <mac> allow-range Mon 7:59 - 18:01