Tagarchief: socat

Playing with the sockets: socat and netcat

Connect two netcats to each other

mkfifo backpipe
nc localhost 55545 0backpipe

Telnet with readline and a history:

socat -d -d READLINE,history=$HOME/.http_history \
TCP4:www.domain.org:www,crnl

Talk to your modem in raw mode:

socat - /dev/ttyS0,raw,echo=0,crnl

Simulate tail -f:

socat -u /var/log/messages,seek-end=0,ignoreeof -

Give a random interactive program, such as nslookup, a history:

socat readline,history=.nslookup_hist exec:"nslookup",pty,ctty,setsid,echo=0

Use your modem with a non-persistent history:

socat readline /dev/ttyS0,raw,echo=0,crlf,nonblock

Use your modem with a persistent history:

socat READLINE,history:/tmp/serial.cmds \
  OPEN:/dev/ttyS0,ispeed=9600,ospeed=9600,crnl,raw,sane,echo=false

To dos (as in tofrodos):

socat -u - -,crlf

From dos (as in tofrodos):

socat -u -,cr -

Run sendmail daemon with your favorite network options

Warning: using this wrong may result in becoming an open relay!

socat TCP-LISTEN:25,fork,ip-ttl=4,ip-tos=7,tcp-maxseg=576 EXEC:"/usr/sbin/sendmail -bs",nofork

Send a mail using chat (from ppp package):

socat -d -d system:'/usr/sbin/chat "220 " "HELO loopback" "250 " "MAIL FROM: <root@localhost>" "250 " "RCPT TO: root" "250 " "DATA" "354 " "test'$(echo -e "\r.")'" "250 " "QUIT"',pty,echo=0,cr tcp:localhost:25,crlf,nodelay

Connect remote X :1 to local X :0

socat exec:'ssh root@troas socat unix-l\:/tmp/.X11-unix/X1 -' unix:/tmp/.X11-unix/X0

Note the escaping of the colon in the remote command.

Sending a file - Server sending the file

server$ socat -u FILE:test.dat TCP-LISTEN:9876,reuseaddr
client$ socat -u TCP:127.0.0.1:9876 OPEN:out.dat,creat

Sending a file - Server receiving the file

server$ socat -u TCP-LISTEN:9876,reuseaddr OPEN:out.txt,creat
client$ socat -u FILE:test.txt TCP:127.0.0.1:9876

Be a syslog server:

socat -u UDP4-LISTEN:5140,reuseaddr,fork OPEN:/tmp/syslog.msg,creat,append

I can't figure out how to put a newline after each message...

Send syslog messages to screen:

socat -t0 -T0 -u UDP4-LISTEN:514,reuseaddr,fork -

To get time from time server:

socat TCP:time.nist.gov:13 -

Really sick - use socat as a VPN solution:

socat -d -d  \
    TUN:192.168.99.2/24,up \
    SYSTEM:"ssh root@remote-server socat -d -d  - 'TUN:192.168.99.1/24,up'"

This must be run as a user that can modify tap/tun devices on both sides of the tunnel.

Use a remote modem

On the side with the modem

socat /dev/ttyS0,raw,echo=0 tcp4-listen:3334

On the side where you want the modem transferred

socat PTY,link=$HOME/vmodem0,raw,echo=0 TCP:servername:3334

You can now access remote /dev/ttyS0 through local $HOME/vmodem0

Use a remote modem over SSH

socat PTY,link=$HOME/vmodem0,waitslave \
 EXEC:"ssh root@remote-server socat - /dev/ttyS0"

You can now access remote /dev/ttyS0 through local $HOME/vmodem0. Remove waitslave to keep alive after local client disconnect.

Using OpenSSL over UDP

This uses a chaining method I believe to be only available in socat2.
On the listening side:

socat2 - "OPENSSL-SERVER,cert=client.pem,cafile=server.crt|UDP4-LISTEN:4430,fork"

On the connecting side:

socat2 exec:ls "OPENSSL-CLIENT,cert=server.pem,cafile=client.crt|UDP4:localhost:4430"

OpenSSL Tunnel

First, generate certificates and distribute them to either side:

FILENAME=server
openssl genrsa -out $FILENAME.key 1024 
openssl req -new -key $FILENAME.key -x509 -days 3653 -out $FILENAME.crt 
cat $FILENAME.key $FILENAME.crt >$FILENAME.pem 
chmod 600 $FILENAME.key $FILENAME.pem 
 
FILENAME=client
openssl genrsa -out $FILENAME.key 1024 
openssl req -new -key $FILENAME.key -x509 -days 3653 -out $FILENAME.crt 
cat $FILENAME.key $FILENAME.crt >$FILENAME.pem 
chmod 600 $FILENAME.key $FILENAME.pem

On the listening side:

socat openssl-listen:4433,reuseaddr,cert=server.pem,cafile=client.crt tcp-connect:localhost

On the connecting side:

socat - openssl-connect:server.domain.org:4433,cert=client.pem,cafile=server.crt

More information:
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© GeekLabInfo Playing with the sockets: socat and netcat is a post from GeekLab.info. You are free to copy materials from GeekLab.info, but you are required to link back to http://www.geeklab.info
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Change VMWare Data Recovery 2.0 report mail

As I may have mentioned before VMWare Data Recovery is not my favorite backup solution. I'm pleased to report that VDR2.0 is a LOT better than 1.x ever was. Since upgrading, my backups haven't failed once. And it even has a built-in email reporting system.

Unfortunately, this mail system isn't too customizable. Since I'd like my subjects to be clear they need extra attention, I made a little fix. This script is started by socat.

Install socat

Socat handles incoming connections on port 25 for me.
rpm -i http://download.fedora.redhat.com/pub/epel/5/x86_64/socat-1.7.1.3-1.el5.x86_64.rpm

Get my script

cd /usr/local/bin ; wget https://www.geeklab.info/wp-content/uploads/2011/12/smtp-filter.sh
You should put your own mailserver in the script on line 7.

Start it automatically

echo "socat TCP4-LISTEN:25,fork EXEC:/usr/local/bin/smtp-filter.sh &" >> /etc/rc.d/rc.local

Now change your settings

Change the outgoing mailserver to localhost and test it. If everything's ok, you'll get a mail with 1 warning and 2 error-message, as the test-mail doesn't contain the fields that indicate no backups failed.

Security

The iptables firewall does not allow incoming connections to port 25, so you will not become an open relay using this script.

© GeekLabInfo Change VMWare Data Recovery 2.0 report mail is a post from GeekLab.info. You are free to copy materials from GeekLab.info, but you are required to link back to http://www.geeklab.info
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