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Re: [A bit OT] Diagnosing home network

On Saturday 20 May 2017 01:41:20 Mark Fletcher wrote:

> Hello!
> I have some doubts about the throughput of my home network and I'm
> hoping for some advice on tools that might help me diagnose it.
> My home network consists of 2 Debian machines, one Jessie and one
> Stretch, an LFS mini-ITX machine acting as my firewall, another LFS
> laptop that is connected only occasionally, a Windows 8.1 laptop, 3
> iPhones of varying ages, 2 iPads, 1 Android tablet device, a couple of
> other proprietary tablets and a Buffalo Linkstation that provides most
> of the connectivity.
> The internet access is via Cable. I run an ethernet cable from the
> cable modem to the firewall machine, then from the firewall machine to
> the Linkstation's WAN port. The firewall machine's WiFi interface is
> disabled (I didn't include its driver when I built the kernel for that
> machine). The Jessie box, a phone-to-ethernet device and a NAS are
> plugged into the Linkstation wired LAN ports. Everything else connects
> to the Linkstation WiFi. The LinkStation offers 2.4GHz and 5GHz
> connections, the 2.4GHz is b/g and the 5GHz is ac I believe. Those
> devices that can use the 5GHz connection, are, the rest are using the
> 2.4GHz.
> I have my doubts about cross-LAN throughput. For example, as I write I
> am using WinSCP on the Windows 8.1 laptop to copy a movie file from my
> Jessie box to the laptop. (The movie concerned is not copyright before
> anyone asks). The Jessie box is connected to the LinkStation by wired
> ethernet, and the Windows 8.1 laptop by WiFi. I am getting a transfer
> rate consistently across the life of the connection of 880KB/s. I'd
> expect it to be a lot faster than that. I checked the WinSCP software
> is capable of limiting the connection speed, but is set not to.
> The laptop is situated here on my desktop, less than 2 feet from the
> LinkStation (albet with a computer monitor between them). Neither
> laptop nor Jessie box were doing anything else at the time -- the load
> on the Jessie box was essentially zero before the transfer started,
> rose to 1 while the transfer was going on, then fell back to basically
> zero when it finished (monitored using xload).
> I'd like to be able to diagnose what's going on here, why the transfer
> was so slow. Any recommendations for tools I should research? I am
> very willing to read man pages etc, but am a bit lost where to start.
> Google gave me a lot of Windows-based stuff which I could look into
> but I would prefer to use Linux-based tools if possible.
> Pointers to tools I should research -- and even better, links to good
> tutorials on those tools if you know any -- would be much appreciated.
> Thanks in advance
> Mark

Couple things here. I have no such problems. My routing is from the cable 
modem, to a buffalo netfinty router running dd-wrt, so I need no 
firewall. dd-wrt has very sharp teeth so I don't seem to need an 
additional guard dog. The output of the buffalo hits an 8 port managed 
switch, and everything else is plugged into that switch. There are 2 
more switch/hubs plugged into that switch so that one cable to the 
garage hitting an 8 port switch in the garage that feeds 3 machines 
there, and another cable thats been blowing in the wind for about 15 
years now, runs from the house to a 12x16 shop building in the upper 
rear corner of the back yard, where always 2, and occasionally a 3rd 
machine is plugged into a 4 port hub.  The 2 8 port switches and the hub 
are gigahertz capable.  Even the machines in the shop building can 
access the internet at megabyte+ a second speeds.  Amanda hits them all 
at about 1:30 am, and even then, with that load on this machine slowing 
it some, I don't notice a huge networking data slowdown.

You'll note no mention of wifi here as its turned off unless I have 
children visiting with their smart phones.  wifi is slower, and subject 
to being used by the neighbors as I found my net usage after the kids 
had been in was up about 80 Gb a month later. I don't couple the wifi to 
my net, only to the internet, but inspecting dd-wrt's list of dhcpd'd 
net leases disclosed that a neighbor seemed to have discovered it and 
was helping himself to my bandwidth. So I had to log back into the 
buffalo and turn the radio off again. As the garage has vinyl siding, I 
have to do the same thing on a raspberry pi 3b out there, which has an 
excellent wifi, and I had to shut it off too. The raspian-jessie 
defaults enable it, and a dhcpd server, so it was handing out addresses 
and connections on wlan0, using bandwidth I could see.  Ooops.  And I 
have to do it everytime I build a new sd card for it. dhcpcd killed 
forever now, or until I change sd cards.

I configured for future expansion, whereas your setup sounds like its 
machine to machine.  So get a router you can reflash, ditch the 
firewall, and feed the routerr (after setting up NAT in the router to 
put your local network on a local address in the 192.168.xx.zz block of 
addresses) and if you must have dhcpcd for your wireless stuff, do it in 
the router. Everything here is in /etc/hosts, resolv.conf says order 
host,dns, and dns is pointed at the router, and forwards dns requests to 
my ISP's dns servers.  And from this end, its all transparent, but the 
black hats are SOL, blocked at the router. I've one  porthole cut in 
that, to allow access to my web page in the sig.  Other than that, no 
one has come thru that setup and gotten into one of my machines in close 
to 15 years.

Cheers, Gene Heskett
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page <http://geneslinuxbox.net:6309/gene>

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