SFTP server Incredibly SLOW

[veaviticus]

I have a simple server set up. Its running the latest build of Ubuntu Server. It is set on a static IP on my router, which is mapped by DynDns to a hostname. When I connect to the server using SFTP via Nautilus on my desktop (connected wired to the same router that the server is connected to) through that internet hostname, I get transfer speeds in the realm of 5-8 Mbps. However, when I do the same technique using my laptop, connected wireless to a network at my school's campus, I get transfer speeds between 20 and 200 BYTES/sec. Painful at best. Even dialing in via the terminal using ssh, getting the login line takes 10 seconds. And once logged in, even typing lags behind, thats how slow the connection is. I can't figure out what would cause things to be so slow when connected wirelessly.

My laptop is a fresh install of Ubuntu 9.04 Desktop, which has not had anything done to it yet (a.k.a putting the hostname in te hosts file or setting up a key-based authorization). I'm pretty new to all this, so I didn't want to mess anything up before I got some confirmation.

Any ideas?

[Lars Noodén]

And ADSL stands for "asymmetric digital subscriber line", the asymmetric part means that the transfer from the Internet to your LAN will be faster than transfers from your LAN to the Internet.

The speed inside your LAN is going to be much faster than your Internet connection, in either direction. Usually it is 10 Mbps, 100Mbps, or 1000Mbps depending on the quality of the router. I'm sad to say that 10Mbps still get sold at high price.

What bandwidth does your ISP advertise that you are supposed to get? Does it say that in your contract?

What are the rudimentary connection speeds TO you home router FROM your school wireless in general?

e.g.

#
ping -c 5 xx.yy.zz.aa

# without dns lookups
traceroute -N 1 -n xx.yy.zz.aa
# or
sudo traceroute -T -N 1 -n -p 22 xx.yy.zz.aa


# with dns lookups
traceroute -N 1 xx.yy.zz.aa
# or
sudo traceroute -T -N 1 -p 22 xx.yy.zz.aa

[veaviticus]

Well I'm not on campus anymore, but I can tell you that at my apartment I have Charter at 10 mbps download speed. I just ran a SpeedTest and got 18.2 megabits download and 2.2 megabits upload speed.
Also, when I connect to my server from within my network, I connect to the external IP address of my router, not through my LAN. So wouldn't I be connecting the same way from my laptop?

thank You much for replying so fast

Robert Nelson

[Lars Noodén]

Well I'm not on campus anymore, but I can tell you that at my apartment I have Charter at 10 mbps download speed. I just ran a SpeedTest and got 18.2 megabits download and 2.2 megabits upload speed.
Also, when I connect to my server from within my network, I connect to the external IP address of my router, not through my LAN. So wouldn't I be connecting the same way from my laptop?


No, it would not be connecting the same way, at least not according to the network topology you originally described. According to that, the simplest possible arrangement would be something like the below. Though it's almost 100% sure to be more steps on the outside.

Also, I'm going to assume that the connection is in Mbps. If you're paying for mbps in 2009 ...


A B C D E F

+--------+
| home | +------+ +---+ +-----+ +----+ +----------+
| server | = A | | I | | C | | W | | school |
| [sshd]<=-----<--= + D<-=-<---=-S-=<----=--A -=<----=--I-=<---= [ssh] |
+--------+ = | S | | P | | M | | F | | notebook |
= | L | +---+ | P | | I | +----------+
+--------+ = | M | | U | +----+
| home | = | O | | S |
| desk | = | D | +-----+
| [ssh]--=----->--= + E |
+--------+ = M |
= |
+------+


Ok.
Between A and anything else on A, you have 10Mbps or whatever your modem is rated as for a hub or switch.

Between B and C, you get, according to the numbers you post, 18.2 mbps going in the direction from C to B download and 2.2 mbps when going from B to C.

Between C and D, as well as from D and E, it's probably going to be the same both directions. It is also probably going to be the fastest part of the link. But for now it is an unknown.

Between E and F, it's going to be slow or if you are sitting where there is a bad signal, slower. Probably around 11Mbps.

So, with those numbers, your connection from F to A is going to be a theoretical maximum of 2.2mbps. However, you lose a bit at each junction.
How many hops were shown in your traceroute test from F to A? That loss is greater if you have other users on the network at the same time. What else do you have running that could be using the bandwidth from B to C?

However, even 2.2Mpbs should be fast enough to type. Again, check your connection from F to A with traceroute to see where the bottleneck might be.

You can also try starting the client requesting compression. -C
However, that will only help if the processor can handle the load.

[veaviticus]

Ok so I'm back on campus. Here's the results of those pings you had me run

I've omitted my vital statistics so its not thrown out there on the interwebs.
__________________________________________________ ___
ping -c 5 xx.yy.zz.aa

PING xxx.yy.com (xx.yy.zz.aa) 56(84) bytes of data.

--- xxx.yy.com ping statistics ---
5 packets transmitted, 0 received, 100% packet loss, time 3999ms


sudo traceroute -T -N 1 -p 22 xx.yy.zz.aa

traceroute to xxx.yyy.com (7xx.yy.zz.aa), 30 hops max, 60 byte packets
1 131.212.196.253 (131.212.196.253) 1.318 ms 2.291 ms 0.909 ms
2 dlh-cb-01-po-2.4012.ggnet.umn.edu (146.57.237.57) 2.555 ms 1.760 ms 1.725 ms
3 192.168.212.194 (192.168.212.194) 15.954 ms 14.590 ms 14.782 ms
4 172.25.0.213 (172.25.0.213) 15.065 ms 20.461 ms 18.667 ms
5 172.25.1.113 (172.25.1.113) 17.283 ms 14.539 ms 14.566 ms
6 172.25.1.106 (172.25.1.106) 15.291 ms 15.109 ms 14.437 ms
7 172.25.1.162 (172.25.1.162) 14.618 ms 14.629 ms 22.777 ms
8 172.25.0.130 (172.25.0.130) 17.568 ms 46.776 ms 14.625 ms
9 172.25.0.158 (172.25.0.158) 14.767 ms 14.979 ms 14.659 ms
10 172.25.0.38 (172.25.0.38) 16.779 ms 15.604 ms 14.925 ms
11 telecomb-bn-02-v3220.ggnet.umn.edu (146.57.238.33) 15.683 ms 15.115 ms 17.173 ms
12 telecomb-br-02-v3229.ggnet.umn.edu (146.57.238.34) 628.327 ms 645.993 ms 570.259 ms
13 telecomb-br-01-te-4-2.ggnet.umn.edu (192.35.86.29) 575.071 ms 564.742 ms 588.210 ms
14 telecomb-gr-01-ten-2-3.northernlights.gigapop.net (146.57.252.178) 604.497 ms 560.637 ms 739.311 ms
15 infotech-gr-01-te-2-1.northernlights.gigapop.net (146.57.252.129) 615.521 ms 649.694 ms *
16 i2cpsv4-nlg.northernlights.gigapop.net (146.57.253.10) 717.586 ms * *
17 eqx.10ge.ord.wvfiber.net (206.223.119.18) 481.870 ms 547.640 ms 542.284 ms
18 mad-ten4-2-chi-ten1-5.wvfiber.net (64.127.129.150) 529.470 ms 553.353 ms 569.949 ms
19 64.127.130.30 (64.127.130.30) 587.706 ms 596.682 ms 581.026 ms
20 crr01ftbgwi-tge-0-1-0-0.ftbg.wi.charter.com (96.34.16.46) 629.874 ms 650.582 ms 553.645 ms
21 96-34-16-77.static.unas.wi.charter.com (96.34.16.77) 538.285 ms 479.656 ms 445.786 ms
22 96-34-16-228.static.unas.wi.charter.com (96.34.16.228) 515.282 ms 505.313 ms 535.343 ms
23 crr01dlthmn-gbe-2-0-0.eucl.wi.charter.com (96.34.16.73) 481.480 ms 421.181 ms 430.926 ms
24 csw01dlthmn-tge-8-1.eucl.wi.charter.com (96.34.16.13) 408.863 ms 386.810 ms 482.359 ms
25 cts02dlthmn-gbe-2-0-0.eucl.wi.charter.com (96.34.25.71) 424.924 ms 425.461 ms 469.305 ms
26 xx-yy-zz-aa.dhcp.dlth.mn.charter.com (xx.yy.zz.aa) 449.800 ms 467.722 ms 574.208 ms
27 xx-yy-zz-aa.dhcp.dlth.mn.charter.com (xx.yy.zz.aa) 52.016 ms 50.140 ms 52.930 ms


I'm not running anything else in the background, a fresh reboot. Opened terminal and ran the commands, so there shoudln't be anything taking up any bandwidth. My router and modem are brand new, with the router being a linksys N router.

I don't know if this provides you with any valuable information. Internet browsing from campus is normal for a wireless signal, the only thing that is slow is accessing my server.

But thank you for taking so much time to explain things to me. I'm learning alot :)

Robert Nelson

[Lars Noodén]

Thanks.

The last step is fast, so it's not your server nor your home network.

The first steps are fast, so it's not your notebook nor the school's Wifi LAN.

You see at step 12, it suddenly gets slower by an order of magnitude?
From the traceroute, these networks are slow, either on purpose or by accident:

ggnet.umn.edu
northernlights.gigapop.net
wvfiber.net
wi.charter.com
mn.charter.com

The operators of those networks would be the ones to contact. There are a lot of reasons for bandwidth to be used up, including Windows worms. Other reasons include over-selling bandwidth, misconfiguration, etc.

You can get the contact information by looking up the ip number in [http://manpages.ubuntu.com/manpages/karmic/en/man1/whois.1.html]whois[/url] or on your contract if you have a direct agreement.

Each step between 12 and 26, about 14 hops, takes about half a second. Again, each step takes a little away from the speed and overall transmission suffers. For the process see http://condor.depaul.edu/~jkristof/technotes/tcp.html