script detecting ssh password request

jp9999 · 05-02-2006, 03:25 PM

hi,

i've been thinking about this for a few days now, and cant find the way to do this.

We're using an api to copy files to the target servers.

We have public key is on the servers, but sometimes (due to overload, unstable ssh version, or whatever) we get "connection refused". If we keep trying, it will eventually work. Also, for the users that don't have the key, i would like to display some error message. So basically, we have a web page to do some stuff, but if in the backgroup we get "connection refused" or the "password" question, i would like to be able to detect that.

I don't want to install expect. Is there a simple way to catch that filehandler (fh 4)?

The only way i've thought of so far is to spawn in the background another process that ssh to the servers, wait a second or so, and look if that process is still there. If it is, it means it was asked for a password. Thats not very elegant tho.

sorry for my poor english/communication.

jp

acid_kewpie · 05-02-2006, 03:46 PM

I'm afraid i have to take you to task on saying that you don't want to install expect. expect it *THE* absolutely obviously and perfect solution to do what you want to do, why won't you use it??

that said... google truns up someones attempt to implement expect purely in bash: http://66.249.93.104/search?q=cache:...implementation

i you can see that or not... timed out many times for me. if not his code looks like this:

Code:

#!/bin/bash

timeout=600

expect() {
local expect="`echo -en $1`" send="$2"
local delim="${expect:(-1):1}"
local buffer="" block=""
while read -u3 -r -t$timeout -d "$delim" block; do
buffer="$buffer$block$delim"
if [ "${buffer:(-${#expect}):${#expect}}" = "$expect" ]; then
echo -en "$send" 1>&3
return 0;
fi
done
}

exec 3<>/dev/tcp/localhost/9999
expect "\377" "guest\n"
expect "Enter name:" "testing\n"
expect "Enter blurb:" "testing2\n"

if you can get that working... also perl has it's own implementation of expect so you could use that maybe.

why apologise for your english? it's better than most americans ;-)