ssh problems

[dannyyee]

My girlfriend has just got ADSL (I can't myself, because I'm on pair gain in North Sydney :-( ) and after a bit of fiddling it's up and running. Most stuff seems to be working (I'm posting this, for example), but my ssh sessions are randomly duplicating characters -- e.g. I'll type "ls" and "lss" will appear (and then "bash: lss: command not found, it's not just an echo problem).

Has anyone experienced this, and what can I do to get around it?

Danny.

[PT_Richard]

No, thats a strange one..

Keyboard bounce ?

Richard

[dannyyee]

I think the ssh problem may not be a (direct) network problem -- it works ok when I ssh from a virtual console instead of a GNOME terminal. But there's definitely some connection with the ADSL connection, as GNOME behaves normally when there's no ADSL connection.

Could packet fragmentation be upsetting some internal desktop polling?

[dannyyee]

Ok, I gave up trying to get the bridged config to work, so I'm now running in vanilla routed mode (with a Netcomm 1300).

But the ssh/GNOME/mozilla problem is still there. Ssh sessions from GNOME terminals have duplicated characters and the desktop gets unusably jerky while (and only while) Mozilla is loading web pages.

However...

File transfers (using scp) are nice and fast. And even big scp transfers DON'T make the desktop go at all jerky.

Ssh sessions work fine (no duplication) from virtual consoles.

Viewing the modem configuration pages doesn't make the desktop go jerky.

I'm still totally perplexed. I think I'll try running KDE just to see what happens :-)

[mbottrell]

Local echo problem?

Checkout your terminal settings...

Cheers,

M@tt.

[taso]

[i]
But the ssh/GNOME/mozilla problem is still there. Ssh sessions from GNOME terminals have duplicated characters and the desktop gets unusably jerky while (and only while) Mozilla is loading web pages.[/B]

What does stty -a tell you?

[dannyyee]

If I take down the ADSL connection and dialup using PPP on a 56k modem, everything works fine - Mozilla doesn't slow everything to a crawl, and ssh works fine (better latency too, as well as no duplication).
So I'm pretty sure it's not a terminal problem. But here's stty -a on the GNOME terminal:

speed 38400 baud; rows 24; columns 80; line = 0;
intr = ^C; quit = ^\; erase = ^?; kill = ^U; eof = ^D; eol = M-^?; eol2 = M-^?;
start = ^Q; stop = ^S; susp = ^Z; rprnt = ^R; werase = ^W; lnext = ^V;
flush = ^O; min = 1; time = 0;
-parenb -parodd cs8 hupcl -cstopb cread -clocal -crtscts
-ignbrk brkint -ignpar -parmrk -inpck -istrip -inlcr -igncr icrnl ixon -ixoff
-iuclc ixany imaxbel
opost -olcuc -ocrnl onlcr -onocr -onlret -ofill -ofdel nl0 cr0 tab0 bs0 vt0 ff0
isig icanon iexten echo echoe echok -echonl -noflsh -xcase -tostop -echoprt
echoctl echoke

and after logging into the remote machine

speed 38400 baud; rows 24; columns 80; line = 0;
intr = ^C; quit = ^\; erase = ^?; kill = ^U; eof = ^D; eol = <undef>;
eol2 = <undef>; start = ^Q; stop = ^S; susp = ^Z; rprnt = ^R; werase = ^W;
lnext = ^V; flush = ^O; min = 1; time = 0;
-parenb -parodd cs8 -hupcl -cstopb cread -clocal -crtscts
-ignbrk -brkint -ignpar -parmrk -inpck -istrip -inlcr -igncr icrnl ixon -ixoff
-iuclc -ixany -imaxbel
opost -olcuc -ocrnl onlcr -onocr -onlret -ofill -ofdel nl0 cr0 tab0 bs0 vt0 ff0
isig icanon iexten echo echoe echok -echonl -noflsh -xcase -tostop -echoprt
echoctl echoke

[taso]

Originally posted by dannyyee
If I take down the ADSL connection and dialup using PPP on a 56k modem, everything works fine - Mozilla doesn't slow everything to a crawl, and ssh works fine (better latency too, as well as no duplication).


That's a good one. The terminal settings look Ok.

I guess the next step is to capture some of the data on the ethernet port with tcpdump and have a closer look at it with ethereal.

First, run script from the gnome terminal and check that the duplicate characters are actually in the typescript file.

[dannyyee]

Now that's weird -- nothing is appearing in the script file at all. But I keep getting messages like

: thrud:~; ls tyypeescriipt
ls: tyypeescriipt: No such file or directory

So the duplicates are definitely not just a display problem! OTOH, if I cut-and-paste into an ssh session, there's no problem... Which suggests some kind of input problem.

So I'm thinking my X server is unhappy. (And X rather than GNOME, since KDE seems to do the same thing.) What kind of network dependencies does the X server have? Is there any way ethernet traffic could upset that?

[dannyyee]

Yes, network traffic of any kind brings X to a near-standstill, with the cursor jerking around abruptly (though I can't get character duplication typing into a local terminal).

But why (how) would X care whether the network connection is ethernet/ADSL or 56k modem/ppp? My brain hurts -- I think I'll go back to reading sea slug haiku and sleep on it.

[taso]

Originally posted by dannyyee
But why (how) would X care whether the network connection is ethernet/ADSL or 56k modem/ppp? My brain hurts -- I think I'll go back to reading sea slug haiku and sleep on it.

If the computer is linked to the ADSL modem by USB then replace it with an Ethernet connection, if it's already Ethernet then put change the NIC and the fly lead. It is sounding like you have a computer hardware fault rather than a software one.

[dannyyee]

It was the evil proprietary nvidia nforce ethernet driver. I added

options nvnet optimization=1

to /etc/modules.conf and now everything works fine. Thanks for helping me track this one down.

[dannyyee]

I spoke too soon...

With options nvnet optimization=1, everything runs smoothly, but after some time (sometimes ten minutes, sometimes an hour) the entire system freezes, with maybe a few keystrokes or mouse movements getting a response minutes later before it locks up completely.

I think I'll buy a real ethernet card and avoid NVidia crap in future.

[mbottrell]

3Com or Intel..... best for Linux... work very reliably. :)

Though Tulip based cards also cut the deal as well. :)

[dannyyee]

Yep, we use 3com and tulips at work.

But I did eventually get it working.. apparently the most recent nforce driver from Nvidia is just broken, but if you take the previous one (but use the build framework from the latest driver, so it compiles on RH9 or Fedora) it actually works!

And I thought getting moving to ADSL would save me having to deal with the evil proprietary winmodem...

Now if I can only get off pair-gain myself, I'll be really happy! (I have a tulip myself :-)