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title	First troubleshooting action

Code Block

language	bash
theme	Midnight
title	traceroute 8.8.8.8 using looback0 as source address

traceroute 8.8.8.8 /vrf inet /interface lo0                            
tracing 8.8.8.8, src=192.168.254.1, vrf=inet, prt=0/33440, tim=1000, tos=0, len=64
1 192.168.254.1 time=0
2 null time=1000
3 null time=1000
4 null time=1000
5 null time=1000
6 null time=1000
7 null time=1000
8 null time=1000
9 null time=1000
10 null time=1000

This confirms the ping failures we observed previously. The output above indicate the packet does not even egress our SOHO router.

What is the inet VRF says ?

Code Block

language	bash
theme	Midnight
title	routes inside VRF inet

show ipv4 route inet                                                   
typ  prefix            metric  iface      hop            time
C    192.168.0.0/24    0/0     sdn1       null           14:30:07
LOC  192.168.0.90/32   0/1     sdn1       null           14:30:07
C    192.168.128.0/24  0/0     sdn999     null           14:30:13
LOC  192.168.128.1/32  0/1     sdn999     null           14:30:13
C    192.168.254.1/32  0/0     loopback0  null           14:30:15

So we have no default routes . Let;'s configure one then pointing towards ISP BOX gateway:

Code Block

language	bash
theme	Midnight
title	Default route configuration

conf t
ipv4 route inet 0.0.0.0 0.0.0.0 192.168.0.254

Code Block

language	bash
theme	Midnight
title	routes inside VRF inet

show ipv4 route inet                                                   
typ  prefix            metric  iface      hop            time
S    0.0.0.0/0         1/0     sdn1       192.168.0.254  14:30:07
C    192.168.0.0/24    0/0     sdn1       null           14:30:07
LOC  192.168.0.90/32   0/1     sdn1       null           14:30:07
C    192.168.128.0/24  0/0     sdn999     null           14:30:13
LOC  192.168.128.1/32  0/1     sdn999     null           14:30:13
C    192.168.254.1/32  0/0     loopback0  null           14:30:15

So at that point, packet send to 8.8.8.8 are sent to nexthop 192.168.0.254 via sdn1.

Code Block

language	bash
theme	Midnight
title	ping 8.8.8.8

ping 8.8.8.8 /vrf inet /interface lo0                                  
pinging 8.8.8.8, src=192.168.254.1, vrf=inet, cnt=5, len=64, tim=1000, ttl=255, tos=0, sweep=false
.....
result=0%, recv/sent/lost=0/5/5, rtt min/avg/max/total=10000/0/0/5003

But ping is still not not working. Let's figure out what's going on here.

...

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title	Netwroking environment assumption

As depicted in previous article:

ISP box has a demarcation point set to 192.168.0.254
So ISO ISP box at some point is configure configured to perform Network Address Translation from 192.168.0.0/24 → ISP public IPv4 interface
When ISP box receives a ICMP ping from 192.168.254.1 which does not match any ISP box NAT rules → Packet is discarded

Therefore in order to have a working seamless networking environment from the ISP box point of view, traffic coning coming from 192.168.128.0/17 shoutd might need to be NAT(ed) into 192.168.0.0/24 network. Let's see If our guess is right.

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title	NAT to the rescue

Let's configure IPv4 Network Address Translation specifically for Loopback0

Code Block

language	bash
theme	Midnight
title	ping 8.8.8.8

!
conf t
access-list ACL-NAT4   
 sequence 10 deny all 192.168.128.0 255.255.128.0 all 192.168.128.0 255.255.128.0 all
 sequence 20 deny all any all 224.0.0.0 240.0.0.0 all                                          
 permit all 192.168.254.1 255.255.255.255 all any all     
exit
!
ipv4 nat inet sequence 10 srclist ACL-NAT4 interface sdn1
!

In the config stanza above we configure an access-list called ACL-NAT4 in VRF inet that would translate all incoming packet matching 192.168.254.1 going to anywhere to interface sdn1 IPv4. But we also don't NAT for inter-vlan traffic within 192.168.128.0/17 and also does not touch multicast traffic.

Code Block

language	bash
theme	Midnight
title	ping 8.8.8.8

ping 8.8.8.8 /vrf inet /interface sdn1                                 
pinging 8.8.8.8, src=192.168.0.90, vrf=inet, cnt=5, len=64, tim=1000, ttl=255, tos=0, sweep=false
!!!!!
result=100%, recv/sent/lost=5/5/0, rtt min/avg/max/total=3/3/4/16

Yahhoooo ! It works ... Our guess was good after all...

Expand

title	Final NAT configuration and subnetting

Expand

title	Final NAT configuration and subnetting assumptions

For the future we assume that the home network is subnetted as follow and are all inside VRF inet:

appliance port#1 @ sdn1: 192.168.0.0/24 (ISP subnet)
appliance port#2 @ sdn2: 192.168.130.0/24
appliance port#3 @ sdn3: 192.168.133.0/24
appliance port#4 @ sdn4: 192.168.134.0/24 (unused)
appliance port#5 @ sdn5: 192.168.135.0/24
appliance port#6 @ sdn6: 192.168.136.0/24
appliance integrated wifi @ sdn998: 192.168.129.0/24
appliance loopback inet @ loopback0: 192.168.129.0/24

Code Block

language	bash
theme	Midnight
title	ping 8.8.8.8

!
conf t
access-list ACL-NAT4
 sequence 10 deny all 192.168.128.0 255.255.128.0 all 192.168.128.0 255.255.128.0 all
 sequence 20 deny all any all 224.0.0.0 240.0.0.0 all
 sequence 30 permit all 192.168.128.0 255.255.255.0 all any all
 sequence 40 permit all 192.168.129.0 255.255.255.0 all any all
 sequence 50 permit all 192.168.130.0 255.255.255.0 all any all
 sequence 60 permit all 192.168.133.0 255.255.255.0 all any all
 sequence 70 permit all 192.168.135.0 255.255.255.0 all any all
 sequence 80 permit all 192.168.136.0 255.255.255.0 all any all
 sequence 90 permit all 192.168.254.1 255.255.255.255 all any all
 exit
!
ipv4 nat inet sequence 10 srclist ACL-NAT4 interface sdn1
!

In the config stanza above we configure an access-list called ACL-NAT4 in VRF inet that would translate all incoming packet matching 192.168.[128|129|130|133|135|136|254].0/24 going to anywhere.

Tip

title	Note

Each time you modify ACL-NAT4 you will need to re-apply the NAT calls:

Code Block

language	bash
theme	Midnight
title	ping 8.8.8.8

!
conf t
! modify access-list ACL-NAT4
!
no ipv4 nat inet sequence 10 srclist ACL-NAT4 interface sdn1
ipv4 nat inet sequence 10 srclist ACL-NAT4 interface sdn1
!

Also notice that we are NAT(ing), 192.168.128.0/24 which is the OOBM subnet of the Linux appliance itself. This is needed during Debian system update/upgrade operation and also needed during the auto-upgrade feature that I'll describe in a next article.

...

Expand

title	Available NAT command verification

Code Block

language	bash
theme	Midnight
title	NAT show commands

language	bash
theme	Midnight
title	NAT show commands

!
show ipv4 nat ?                                                        
  <vrf> - name of routing table
!
show ipv4 nat inet ?                                                   
  statistics   - list of configuration entries
  <vrf>translations - namelist of routingtranslation tableentries
!

Expand

title	Trigger NAT traffic translation

Code Block

language	bash
theme	Midnight
title	ping 8.8.8.8 in order to trigger NAT translation

ping 8.8.8.8 /vrf inet /interface lo0                                 
pinging 8.8.8.8, src=192.168.254.1, vrf=inet, cnt=5, len=64, tim=1000, ttl=255, tos=0, sweep=false
!!!!!
result=100%, recv/sent/lost=5/5/0, rtt min/avg/max/total=2/3/4/16

...

We finally have a router that enables connectivity for all host hosts inside the home network to the outside world
due to the ISP specific setup, our router had to translate inner home IP subnets to subnet that can be in turn NAT'ed by the ISP box.
We have a consistent IPv4 addressing plan
We all now can add very exciting feature from now on. But it will be in other articles(In next articles !)

Tip

title	RARE validated design: [ SOHO #004 ] - key take-away

In this example we are proposing a basic connectivity scenario. However, keep in mid mind that depending on your location the configuration might be drastically different. But do not fear ! RARE/freeRouter has all the features need to enable connectivity !

NAT64 is available. So in case you want to run a pure IPv6 network, freeRouter can propose NAT64 traffif for you.
NAT46 is also available. In case you are desperate and don't want to implement an a pure IPv6 home network and have an ISP running only IPv6, freeRouter can NAT46 your traffic for you !
In the example described, we are lucky to have IPv6 public global IPv6 address. We will see IPv6 configuration in subsequent articles.

...

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