Problem: We use Zabbix as monitoring system. In addition to using its built in items, we also use something called external scripts feature (this), where custom scripts can be written and called via Zabbix. The problem facing here is its getting timed out. Script is simple expect file which goes inside a device and pulls some data. This works when called via root. But when called via Zabbix user, its complaining
/usr/bin/expect: /usr/bin/expect: cannot execute binary file
Script looks like this,
#!/usr/bin/expect
set host "IP_ADDRESS"
set uname "username"
set pwd "password"
set prompt "#|>|:|\\\$";
set val ""
set domain [lindex $argv 0]
log_user 0
set timeout -1
spawn /usr/bin/ssh "$uname@$host"
expect "$uname@$host's password:"
send "$pwd\n"
sleep 1
#expect -re "$prompt"
expect ">"
sleep 1
send "show wireless rf-domain statistics detail on $domain | grep Signals\r"
sleep 1
expect ">"
set val $expect_out(buffer)
send "exit\n"
puts $val
This is named as rf_signal.exp. Its called via a wrapper shell script named rf_signal.
#!/bin/bash
val=$(/usr/bin/expect '/usr/local/etc/scripts/rf_signal.exp' $1 | grep 'RF Signals' | cut -d':' -f2 | cut -d',' -f1 | cut -d' ' -f3 | sed -e 's/\s//g')
echo "$val"
And if called as root, this works fine for example
[root@zbx-proxy2 externalscripts]# pwd
/usr/local/share/zabbix/externalscripts
[root@zbx-proxy2 externalscripts]# whoami
root
[root@zbx-proxy2 externalscripts]# /usr/local/share/zabbix/externalscripts/rf_signal DOMAIN_NAME
241
[root@zbx-proxy2 externalscripts]#
Where as if I call as zabbix user I am getting, cannot execute binary file error. With expect as a path
[root@zbx-proxy2 externalscripts]# runuser -l zabbix /usr/bin/expect /usr/local/share/zabbix/externalscripts/rf_signal
/usr/bin/expect: /usr/bin/expect: cannot execute binary file
[root@zbx-proxy2 externalscripts]#
Without expect as a path, it waits -
[root@zbx-proxy2 externalscripts]# runuser -l zabbix /usr/local/share/zabbix/externalscripts/rf_signal
PSTree command output shows it calls expect and contents inside the file
[root@zbx-proxy2 ~]# pstree -p 26295
runuser(26295)---bash(26296)---bash(26309)-+-cut(26312)
|-cut(26313)
|-cut(26314)
|-expect(26310)---ssh(26316)
|-grep(26311)
`-sed(26315)
PS details.
[root@zbx-proxy2 ~]# ps aux | grep zabbix | grep -v "proxy\|agent\|fping"
root 26295 0.0 0.0 130700 1388 pts/3 S+ 15:46 0:00 runuser -l zabbix /usr/local/share/zabbix/externalscripts/rf_signal
zabbix 26296 0.0 0.0 108184 1628 pts/3 S+ 15:46 0:00 -bash /usr/local/share/zabbix/externalscripts/rf_signal
zabbix 26309 0.0 0.0 108184 576 pts/3 S+ 15:46 0:00 -bash /usr/local/share/zabbix/externalscripts/rf_signal
zabbix 26310 0.0 0.0 115336 2260 pts/3 S+ 15:46 0:00 /usr/bin/expect /usr/local/etc/scripts/rf_signal.exp
zabbix 26311 0.0 0.0 103260 868 pts/3 S+ 15:46 0:00 grep RF Signals
zabbix 26312 0.0 0.0 100972 676 pts/3 S+ 15:46 0:00 cut -d: -f2
zabbix 26313 0.0 0.0 100972 672 pts/3 S+ 15:46 0:00 cut -d, -f1
zabbix 26314 0.0 0.0 100972 676 pts/3 S+ 15:46 0:00 cut -d -f3
zabbix 26315 0.0 0.0 105268 872 pts/3 S+ 15:46 0:00 sed -e s/\s//g
zabbix 26316 0.0 0.0 59856 3220 pts/14 Ss+ 15:46 0:00 /usr/bin/ssh username@IP_ADDRESS
root 26688 0.0 0.0 105324 912 pts/7 S+ 15:47 0:00 grep zabbix
[root@zbx-proxy2 ~]#
All the scripts have read and execute permissions to all the users. And expect/grep/cut - whatever used inside the scripts are having read/execute permissions. What could be the issue?
