strange ssh performance issues
kevin at kevinkempterllc.com
Fri Sep 28 16:52:37 UTC 2007
First let me say that (1) I have a fairly unusual (I suspect) ssh setup, and
(2) I hate the virus known as windows
Here's the deal;
The client I'm working for uses a SonicWall firewall to control access to the
data centers. Unfortunately there are issues with the Linux openVPN clients
(specifically open swan) where it connects but locks all other connections
out of the firewall. So, until we figure this out the solution is to use the
windows version of the SonicWall client. I've installed vmware and installed
a copy of VirusXP (AKA Windows XP). I installed cygwin and followed the
instructions here to install the ssh server:
( http://pigtail.net/LRP/printsrv/cygwin-sshd.html ) although I did not run
the mkpasswd and mkgroup commands, they seemed to break the install of ssh
Anyway, I also setup an ssh key so I could login to the M of VirusXP without a
Next I setup a config file in my Linux $HOME/.ssh dir with many entries like
this (one for each host in the data ceners that I need to connect to):
Hostname 10.1.x.x # data center I.P.
HostKeyAlias 10.1.x.x # data center I.P.
ProxyCommand /usr/local/bin/netcat-proxy-command 172.16.128.128 %h
The 172.16.128.128 I.P. addr is the I.P. of the VirusXP image within vmware
via nat. (I could not make the ssh connections work via bridged networking).
The /usr/local/bin/netcat-proxy-command script is a netcat (nc) script and
ssh $gateway nc -w 1 $internal 22
To use this setup I boot up VirusXP, open the SonicWall VPN client and connect
to one or more of the data centers. Then in Fedora 7 (the host OS) I open a
terminal and run this:
so, to my issue. Most of the time this setup works fairly well, in that it
does connect. It usually takes about 30 seconds for me to get a password
prompt for the target data center host. This is acceptable but I think
there's something weird going on that delay's the connection. I say this
because I can open a cygwin windowin VirusXP and do an ssh <I.P.> and I get a
password prompt immediately.
The main issue is that several times a day the connections start to take
several minutes to return the password prompt. I need to restart the cygwin
service in VirusXP, and sometimes that doesn't help so I reboot the VM
instance of VirusXP. This is quite frustrating, however I'm a DBA and have
limited networking knowledge. Does anyone have any thoughts?, suggestions?,
Thanks in advance..
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