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Old 10-16-2003, 06:06 PM   #1
LQ Newbie
Registered: Oct 2003
Posts: 5

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Unhappy my PuTTY connection over ssh is too slow.


I have been using PuTTY from my W2K laptop at home to connect to my school machines running latest stable Debian distribution for 6 months now. All I'm doing is editing with emacs and compiling code, not trying to run X or anything like that. I have ssh 2 set up and working fine, so that I just load the session I want in PuTTY, open it, and it logs me in using the key on my laptop and the key at school. That much is great.

My connection however gets very slow at times, and I was wondering if I can do anything about it (or get the sysadmin at my lab to do anything about it ... somehow I doubt that my ISP will help). I have high-speed connection, with an upload speed of about 100 kbps, and so I would expect reasonably fast input.

However, sometimes it seems that things just slow to a crawl. It can take over a second between when I press a character and when it appears on the terminal output. Sometimes the speed is acceptable enough to edit though, and I'm happy. What's strange is that it doesn't depend on the time of day or day of the week, so I don't think it's an internet congestion problem.

The settings in the "Connection" part of my PuTTY session are as follows:

terminal-type string: xterm
seconds between keep-alives: 30
diable nagle's algorithm: checked

-- proxy submenu: no proxy being used
-- telnet submenu: not used
-- rlogin submenu: also not used
-- ssh submenu:

don't allocate a pseudo-terminal: unchecked
enable compression: checked
preferred ssh protocol version: 2
encryption cypher selection policy: aes (ssh 2 only); blowfish; 3DES; -- warn below here -- ; DES
enable non-standard use of single-DES in SSH 2: unchecked

-- ssh auth subsubmenu:
attempt TIS: unchecked
attempt keyboard-interactive: checked
allow agent forwarding: checked
allow attempted changes of username in ssh2: unchecked

-- ssh tunnels subsubmenu:
enable x11 forwarding: unchecked
local ports accept connections from other hosts: checked
remote ports do the same (ssh2 only): checked
forwarded ports: none

-- ssh bugs subsubmenu:
all options set to "auto"


other than that, i connect at home over a wireless card to my router (11 Mbps), i was thinking that maybe the delay is occurring at my router for some reason (it seems that cycling the power on my router / internet dsl modem box thing helps a little bit). it's an smc wireless barricade.

anyway, i'm really only posting this because it's so bad that i'm editing files these days by tarring them all up, downloading them from my public_html directory using my browser, editing in emacs for windows, tarring them all up again, sending them back over scp (really painfully slow), and compiling at school, and repeating the whole stupid process. what's worse is that when i untar the files, all the permissions have been reset, and i can't build anymore, so i have to commit to cvs, delete my working directory, and checkout again.

if you think there's some setting on my router that we can change, and that there's nothing at school or on my laptop, then i can post shots of my router configuration window. no, i am not encrypting the connection to my router -- although i don't think somebody else is stealing my bandwidth. i suppose i could try encrypting the connection, but that's supposed to cut speed even further. um ... anything else??? ... um ... i'm not running any other network applications while i'm trying to use putty.

okay, well i appreciate any and all help, i really need a resolution to this problem, even if it means switching isp's, because i need to work from home a lot lately and can't go to my lab. at school, i also use my wireless card, but things are a lot faster, presumably because the AP is already behind the school firewall(s). however, i also don't really expect to find an answer because somehow something tells me this can't be too fixed.

Old 10-16-2003, 06:12 PM   #2
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Registered: Oct 2003
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yes i've tried winCVS in the past, i suppose i'll just have to start using it again if i can't get putty to be fast enough. which kind of sucks because i'd rather not need to check code in until i've tested it (that way i can just maintain my own quasi-stable branch and not need stable and unstable branches). and pretty soon (within a couple of weeks i hope, because everyone else already is) i'll be using subversion anyway and iirc there's no win32 client.
Old 11-22-2003, 02:57 AM   #3
Registered: Mar 2003
Location: el paso
Distribution: Redhat, Suse, and freebsd
Posts: 90

Rep: Reputation: 15
Not, really complex....

Unfortunately, I use putty at school all so and have set my Linux server to allow hosts to access
through putty....

What happens and makes it slow is the encryption the route traveled and having to support the ssh protocol...

Look at this way anytime you send a msg lets say small to 1mb well first the computer will request a use of the bandwidth say 1mb the signal will splits the file and send it across the Internet...

Now add ssh this is were encryptions become costly to administrators and company's.

First this would look like this....

(The Computer your on)...

1. Would establish contact with (computer acting as a server)
A. Computer sends request to establish ssh tunnel
B. Server receives request and forwarders you to login.
C. You type in name and password.
D. Server verify's name and password to own database.
E. You know have established a session with the server and can begin transferring files.

2. While all this encryption and decryption takes place it burns up bandwidth.

Before you even request a file all the login and ssh tunnel session must establish....

Now the raw numbers in this event.

1. Before ssh msg would only use a maximum of .5 mb of bandwidth for up to the time of requests both login and file transfer...

2. Using ssh your bandwidth usage will start at .5mb of information being passed as log as your logged into the Server...

Now sending a file across this type of media results in bandwidth increases and if the file is say 2mb of data the time to receive packets from a computer to computer session and decrypt this data may take a while...

We didn't add routers that have to support ssh and the possibility that your message may not be using the "best path" stated by the router do to the type of encryption.....

What makes Administrators and Analysts having to do billing or justify the extra expenses for security. Which you will find most Analysts or Upper Level Administrators in this responsibility for security issues and the absorbent amounts of money being billed to Company's.

Mainly, this issue alone is the reason major company's hire analysts to measure Cost, Employment, Databases, security issues and overall performance of the IT department.

If you were to put a IT administrator in charge of security they would probably choose kerbovues 5 at 256 bit encryption and run up all kinds of bills for Internet connections...

That is why you find more major company's use proxy to allow you off the system and no one on the system....

I suggest if your that interested in sending files to school with you use a USB flash stick...

Save your time in fighting putty....

Well I hope this cleared up any misunderstanding....

Now a days you'll find major company's use X Server to bring down costs of windows, Macintosh, linux and novell clients able to access any Type of Server...

later and good luck on a solution....


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