strange network failure

  • Thread starter Thread starter Cacadril
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Cacadril

I can reach the Internet using Firefox, but not using Google Chrome.
Google Chrome always times out. Sniffing the network using Wireshark,
there are three TCP SYN packets and no responses if I try to connect
using Google Chrome. When I installed Chrome a week ago, it did work.
I have been away the rest of the week, and now that I am back Chrome
does not work. I have tried to reinstall. Installing from IE first
popped up a dialog telling it was checking prerequisites, then a
dialog telling the installation had failed, check your network or
contact your system administrator. Installing from Firefox worked, but
the newly installed Chrome failed as before.

Stranger still: using PuTTY, the ssh client, I connect to another
computer on the local network. Using psftp, which comes in the same
bundle as putty, the network is dead. I get the error "Network Error:
Connection timed out" even as I run commands in the PuTTY window at
the same time and get responses. I run wireshark on both computers. On
the client, the SYN packets show up when I run psftp, but on the
server they do not. In the same run of wireshark and with the very
same capture filters (tcp and host x.x.x.x and host y.y.y.y), when I
start PuTTY on the client, the syn and syn-ack packets show up in both
wiresharks, and the connection is established.

Notice that psftp is a command line program that runs in a cmd window,
while PuTTY has its own window. Could that be related? Chrome is of
course not a command line program. Could this be related to user/admin
modes?

I use BitDefender, but it has stopped responding. A couple of reboots
has not helped. When I try to run the antivirus update, it downloads
about two megs of data, then hangs. In Wireshark I see that the
transfer is uneven. In the end it stops; the server keeps sending tcp
keepalive, but the updater responds with zerowindow until the server
resets.

Any ideas? Any similar experiencs?
Thanks
 
I can reach the Internet using Firefox, but not using Google Chrome.
[...]
Stranger still: using PuTTY, the ssh client, I connect to another
computer on the local network. Using psftp, which comes in the same
bundle as putty, the network is dead. I get the error "Network Error:
Connection timed out" even as I run commands in the PuTTY window at
Click to expand...

You have a firewall problem. Since it doesn't seem to be port
related (chrome and firefox are both using port 80) it's probably
an application firewall running on your windows box.

It's not impossible that you have some kind of malware infection.
They're known to cause similar problems. You can't diagnose this sniffing
from the effected host. You need to put a hub or tap in front of that host
and examine traffic as it arrives at its interface:


HUB
| \
| \
| \
host sniffer

You're getting misleading results because something's causing it
to discard packets before they get to wireshark. But a thorough software
audit would be a better place to start IMHO.

You might try putting a hair dryer on it... (ha ha)
 
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