Ubuntu/Scripts

Revision as of 00:17, 26 September 2015

Email current IP address

Variables needing to be defined:

• sender domain (@sender domain.com)
• recipient (recipient address)
• recipient mail exchanger (recipient mail exchanger) ---FIXED, no longer needed

Variables automatically defined

• HOSTNAME - defined by using the hostname command
• DATE - defined by using the date command
• IP - queries checkip.dyndns.org and then parses the return to exclude everything except the IP address
• UPTIME - defined by using the uptime command
• USERS - defined by using the users command
• RECIP_DOMAIN - defined by parsing the domain from the recipients' address
• RECIP_MX - defined by querying the recipient's MX and picking the record with the highest priority
• MESSAGEID - automatically created using random numbers and the sender's domain

Code

#!/bin/bash -x

#static variables
from="$HOSTNAME"'@sender domain.com'
to='recipient address'

#dynamic variables
HOSTNAME=$(hostname)
#recipient_mx='recipient mail exchanger'   ---obsolete
DATE=$(date -R)
sender_domain=$(printf "$from" | sed 's/^.*@//')
messageidrandom=$(od -vAn -N4 -tu4 < /dev/urandom)
messageidrandom=$(printf "$messageidrandom" | sed 's/ //')
messageid="$messageidrandom"'@'"$sender_domain"
IP=$(curl checkip.dyndns.org|awk '/Address:/ {print$6}'|sed 's/<.*/ /')
UPTIME=$(uptime)
USERS=$(users)
recip_domain=$(printf "$to" | sed 's/^.*@//')
recip_mx=$(dig +short $recip_domain mx | sort -n | nawk '{print $2;exit}' | sed 's/\(.*\)./\1/')

#function containing mail commands.  Contains enough RFC required fields to satisfy gmail's requirements to allow the message, though it may be detected as spam if you do not have a SPF record.
 function mail_input {
         sleep 1
         printf 'ehlo test.com\n'
         sleep 0.5
         printf 'mail from:<'"$from"'>\n'
         sleep 1
         printf 'rcpt to:<'"$to"'>\n'
         sleep 1
         printf 'data\n'
         sleep 0.5
         printf 'Return-Path: <'"$from"'>\n'
         printf 'Date: '"$DATE"'\n'
         printf 'Message-ID: <'"$messageid"'>\n'
         printf 'Subject: '"$HOSTNAME"' ip address= '"$IP"'\n'
         printf 'From: <'"$from"'>\n'
         printf 'To: <'"$to"'>\n'
         printf '\n'
         printf '\n'
         printf 'hostname='"$HOSTNAME"'\n'
         printf 'ip address= '"$IP"'\n'
         printf 'uptime= '"$UPTIME"'\n'
         printf 'users logged in= '"$USERS"'\n'
         printf '.\n'
         sleep 3
         printf 'quit'
         kill $$
 }

#sending mail with mail_input function
#plain text
mail_input | telnet $recip_mx 25
#TLS encrypted
#mail_input | openssl s_client -crlf -starttls smtp -quiet -connect $recip_mx:25

Learned

• you cannot define a variable as the same exact spelling of the command.

WRONG: hostname ≠ `hostname`
RIGHT: HOSTNAME = `hostname`

• you can call a standard command and define its output as a variable, so long as you use " ` " around the command (old school) or "$( )" around it

WRONG: HOSTNAME ≠ 'hostname'
RIGHT: HOSTNAME = `hostname`
RIGHT: HOSTNAME = $(hostname)

• when using printf you should be careful which type of quote to use. a single quote should be used for plain text, such as a static heading to an output. a double quote should be used for defining variables.

WRONG: printf "Address: " '$IP' "\n"
RIGHT: printf 'Address: ' "$IP" '\n'

adding -x to your #!/bin/bash statement will cause everything to be printed, useful in troubleshooting

#!/bin/bash -x

• a wise man told me that i'm supposed to separate the headers from the body of the message with (2) linefeeds. Added to the script.