[arm-allstar] Allstar and Network management

[Doug Crompton]

Just a few notes on Allstar and network management.

In an earlier message Dave gave information on manually configuring a
network. This information is for the more experienced user and I caution
that you can really screw things up mucking in those files if you don't
know what you are doing. The stock setup network configurations of DHCP or
static will suit 99% of users.

There are many different routers out there. Many are using old that can
sometimes cause problems. For most things you do with devices on the
internet, browsing the web, streaming video, etc it matters less what IP
address you are assigned but for others like your Allstar server it does
matter because you may need to directly interact with it via ssh (putty)
and port forward in your router for incoming connections.

In most all cases using the default DHCP works fine. Your router assigns
you an IP address and as long as you stay online you will have the same
address. Even if you went off line for a period less than the DHCP lease
length when you came back up you would be issued the same IP address. To
make that IP address stick permanently you could configure your router to
always assign the same IP address based on the mac address of your board.
The board address does not change and is a unique address. Every Pi board
made will have a unique MAC address. So if you locked down a DHCP address
using hamvoip version 1.02 the same address would be assigned bringing up
V1.5. Even if you ran a completely different OS, say Jesse Pixel by
swapping SD cards, you would have the same IP address. With DHCP the IP
address is assigned to the board not the SW running on the board. The
advantage here is that you always know what IP address is going to be
assigned to that board. This of course assumes you have it setup in your
router and you do not change routers.

The DHCP permanent IP address feature is variously called *static DHCP
assignment *by DD-WRT, *fixed-address* by the dhcpd documentation, *address
reservation* by Netgear, *DHCP reservation* or *static DHCP* by Cisco and
Linksys, and *IP address reservation* or *MAC/IP address binding* by
various other router manufacturers.

Issues that often crop up with home LANs is having more than one router
online with BOTH issuing DHCP addresses. You should ONLY have one DHCP
server on a LAN. There are situations where more than one can be used but
this is for experienced users with network experience. Another problem that
often crops up is serially connected routers creating a double NAT. In this
scenario router one converts a single public IP from your provider to a LAN
assignment say 192.168.1.x then you connect another router from one of the
first routers LAN ports to the second routers WAN port. The second router
DHCP's an IP from the first router and then creates yet another LAN behind
the first LAN. The proper way to do this if you use two routers is to
connect the first router to the second routers LAN port (LAN to LAN NOT
WAN) and essentially making the second router a switch BUT you do need to
turn off the DHCP server in one of the routers! Many people use multiple
routers mainly to put up multiple wireless access points. There is nothing
wrong with doing this you just have to watch how you connect things. Never
double NAT (always LAN to LAN between routers) and ONLY ONE DHCP server on
the network.

I have experienced several Allstar users pull their hair out having routers
connected in the wrong way and trying to port forward only to find it does
not work. If you have Allstar connected to the second serially connected
router (LAN to WAN) and you port forward in that router you are only port
forwarding to another LAN not the internet and it will not work.


*73 Doug*

*WA3DSP*

*http://www.crompton.com/hamradio <http://www.crompton.com/hamradio>*