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List:       loadbalancing-l
Subject:    Re: [load balancing] healthcheck script hints for Alteon
From:       Jay Kline <list () slushpupie ! com>
Date:       2003-05-21 14:12:27
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Using telnet is not a great idea- the telnet protocol defines all sorts of 
control characters and doing a simple TCP connection will yeild less than 
desirable results.  A better idea would be to connect to the service itself 
to see if it works.  Some of the basic protocols are already set up, but if 
you have a different protocol, it would be worth learning how it works to be 
able to check the service itself.  For example, we have a custom DNS resolver 
that runs on TCP port 8007:

open 8007
send "somedomain.com\n"
expect "OK"

Jay


On Wednesday 21 May 2003 03:12 am, julian.herzel@accenture.com wrote:
> Hi,
>
> We have an Alteon 184 and I'm trying to configure a healthcheck for a UDP
> service running on our real servers. The standard ICMP healthcheck provided
> by the Web OS picks up the service as being "up" even when it's not running
> on the port, so I'm trying a custom script to tell the Alteon the status of
> this service.
>
> The simplest way I can think of is via a controlled telnet to the host
> (Solaris) which upon successful login automatically executes something as
> simple as a
>
> ps- ef | grep "service"
>
> which returns the result and then promptly logs the user off.
>
> I have the following script:
>
> open 23
> expect "login: "
> send "login_ID\r"
> expect "Password: "
> send "login_passwd\r"
> expect "service"
>
> This script is currently failing.
>
> When executed as a normal telnet from a command prompt it gives following
> output (for send of the login_passwd).
>
>       Last login: [date/time] from host
>             [user]     [process_ID]    1  0   [date]    service
>
>       Connection to host lost
>
> Is it failing because the host is forcing the connection closure rather
> than the Alteon?
> Any other ideas on best practice for this type of healthcheck?
>
> Thanks in advance,
>
> Julian
>
>
>
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-- 
Jay Kline
http://www.slushpupie.com

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