We have satellite modems and small servers installed in plenty of odd, rough, remote rural places, and satellite modems can be persnickety beasts. The provider claims they're all identical but some hand out static IP's over dhcp, some don't. Some respond to DHCP, some don't. They all have a nice parse-able web interface for runtime statistics, but not always the same parse-able web interface for runtime statistics. Trying to deal with their eccentricities in an automatic way can be a bit troubling if you want a uniform set of systems.
With a bit of wrangling I found an arrangement that worked in most situations. Usually the modems give a static address over DHCP, or a NAT address over DHCP, but a few odd ones don't respond at all, so I used dhcp failovers to auto-set the server's WAN port to an 192.168.x.x address when DHCP failed. Finally I could have the same settings work on all of my servers and modems, with actual static IP's when available, and it was good.
A little while later, a minor but important security fix came through for dhcpcd. In-house testing showed it properly picking up IP's, and the rest of the changes looked absolutely minor, so I deployed it. Most servers kept running... a few didn't. 100km later I was sitting on a bucket in a grimy, tick-filled wooden shack trying to figure out what the machine in front of me was doing to itself.
Code:
$ ifconfig wan
wan Link encap:Ethernet HWaddr 00:08:C7:E3:A1:13
inet addr:169.254.32.239 Bcast: ...
The not-so-insignificant new feature turned out to be zeroconf support, enabled by default. This means failure is a perfectly acceptable outcome for dhcpcd now. On timeout it sets a useless random IP and returns success. No error, no failover; no failover, no network connection. One extra flag in dhcpcd's default options, a few long drives, and everything worked fine again.
I don't want to kill whoever decided zeroconf was a sane default for the world, but I'd at least like to pie him.
Last edited by Corona688; 01-13-2012 at 01:16 PM..
uucpsetup(8) System Manager's Manual uucpsetup(8)NAME
uucpsetup - The uucp setup program
SYNOPSIS
/usr/sbin/uucpsetup [-moiap]
OPTIONS
Adds modems, configuring the dialers for uucp. Adds incoming systems; that is, systems that are allowed to call your local system. Adds
outgoing systems; that is, systems that your local system is allowed to call. Adds the modems and incoming and outgoing systems to uucp.
The -a option implies the -m, -i, and -o options. Adds the system name to /usr/lib/uucp/Poll file.
DESCRIPTION
The uucpsetup command provides an interactive facility for setting up and updating the uucp files necessary to configure your system for
uucp connections.
To set up uucp initially, run the uucpsetup command with the -a option and answer the questions. To update the uucp files and directories,
run uucpsetup with the -m, -o, or -i options, as appropriate. If no options are specified, the -m, -o, and -i options are the default.
You must be superuser to run uucpsetup.
FILES
Contains information about available devices. Contains access permission codes for remote systems. Lists accessible remote systems. Con-
tains the polling option for each remote system.
SEE ALSO Devices(4), Permissions(4), Poll(4), Systems(4), uucp(1), uucp_intro(7)
Network Administration
uucpsetup(8)
01-13-2012
