ssh tunneling question

  • Thread starter Thread starter G.T.
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G

G.T.

Ok, we're heavily proxied here so no direct access to NNTP servers but we do
have a telnet proxy. So, using putty.exe I forward local port 4019 through
my home OpenBSD server to news.dslextreme.com:119 :

OE -> 127.0.0.1:4019 -> 52.98.124.2 -> news.dslextreme.com:119

Everything works fine except that our telnet proxy is unreliable so putty
will eventually lose connection to my OpenBSD box. For the first 4 or 5
disconnects I can simply start up putty and connect home again, and OE is
fine. However, on the 5th or 6th time OE just won't connect to the tunnel.

Checking netstat I see:

TCP butvthomasgnbc:4019 butvthomasgnbc.nbc.com:1304 CLOSE_WAIT
TCP butvthomasgnbc:4019 butvthomasgnbc.nbc.com:1313 CLOSE_WAIT
TCP butvthomasgnbc:4019 butvthomasgnbc.nbc.com:1317 CLOSE_WAIT
TCP butvthomasgnbc:4019 butvthomasgnbc.nbc.com:1318 CLOSE_WAIT
TCP butvthomasgnbc:4019 butvthomasgnbc.nbc.com:1344 CLOSE_WAIT

Those are the only ports for 4019 that I see in the netstat output. I'm not
up on TCP so I don't yet know what CLOSE_WAIT means. I realize that the
constant disconnects are leaving ports open because putty isn't gracefully
shutting them (I would guess). The only thing that works is rebooting or
forwarding a different port and reconfiguring OE. After changing the local
port to 5019 and updating OE I see this:

TCP butvthomasgnbc:4019 butvthomasgnbc.nbc.com:1304 CLOSE_WAIT
TCP butvthomasgnbc:4019 butvthomasgnbc.nbc.com:1313 CLOSE_WAIT
TCP butvthomasgnbc:4019 butvthomasgnbc.nbc.com:1317 CLOSE_WAIT
TCP butvthomasgnbc:4019 butvthomasgnbc.nbc.com:1318 CLOSE_WAIT
TCP butvthomasgnbc:4019 butvthomasgnbc.nbc.com:1344 CLOSE_WAIT
TCP butvthomasgnbc:5019 butvthomasgnbc.nbc.com:1549 ESTABLISHED

Is there a timeout for those CLOSE_WAITs? They've only been there since
yesterday afternoon after my last reboot (I've got a Dell GX270 with a
capacitor problem, just got a replacement mobo but haven't switched it out
yet).

Is this a red herring? Is there a max of 5 CLOSE_WAITS on a port?

Thanks,
Greg
 
Mark R. Blain said:
I can't help with your problem, but I can at least tell you that much.

From RFC793 (TCP):

CLOSE-WAIT - represents waiting for a connection termination request
from the local user.
Click to expand...

Thanks, I should have looked this up by now.

So, usually after hitting 5 of these I can no longer connect. Does anyone
know if this is a configurable setting on W2K?

If it's not configurable, is there anyway to close these? Since the
connection has already been lost to that local port # I can't give it the
termination request. I haven't found anything showing that these
CLOSE-WAITs will timout.

Greg
 
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