Tunnelling UDP Traffic Through An SSH Connection: Difference between revisions

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== Overview ==
== Overview ==
This section describes how to use '''NST''' to tunnel a '''UDP''' network traffic conversation through a '''SSH''' connection. For our example we will tunnel '''[http://ipmitool.sourceforge.net/ IPMItool]''' traffic ('''UDP''' Port: "'''623'''") through  an '''SSH''' connection to a '''Sun Fire X4200''' server's '''Integrated Lights Out Manager''' ('''ILOM''') service processor network interface. Three systems are involved, 2 '''NST''' probes and the '''X4200''' server. Reference information was taken from: "'''[http://zarb.org/~gc/html/udp-in-ssh-tunneling.html Performing UDP tunneling through an SSH connection]'''".
This section describes how to use '''NST''' to tunnel a '''UDP''' network traffic conversation through an '''SSH''' connection. To demonstrate the effective use of UDP tunnelling, we will show how to remotely interrogate a '''Sun Fire X4200''' server's  '''Integrated Lights Out Manager''' ('''ILOM''') service processor. The command line utility: "'''[http://ipmitool.sourceforge.net/ IPMItool]'''" generates ('''UDP''' Port: "'''623'''") ('''IPMI''' - '''I'''ntelligent '''P'''latform '''M'''anagement '''I'''nterface) traffic which will travel through  the '''SSH''' connection to the remote '''Sun Fire X4200''' server's '''ILOM''' service processor network interface.


== Step By Step Instructions: ==
'''IPMI''' over '''LAN''' (i.e. a '''TCP/IP''' network) uses the '''Remote Management Control Protocol''' ('''RMCP''') to support pre-OS and OS-absent management. '''RMCP''' is a ''request-response'' protocol using '''UDP''' datagrams on port: "'''623'''".
 
The network topology below depicts the three systems that are involved, 2 '''NST''' probes and one '''Sun Fire X4200''' server. Reference information was taken from: "'''[http://zarb.org/~gc/html/udp-in-ssh-tunneling.html Performing UDP tunneling through an SSH connection]'''".
 
== Network Topology ==
 
Use this network topology as a reference for tunnelling '''UDP''' traffic through an '''SSH''' connection.
 
[[Image:Nst udp ssh.png|center|Network Topology]]
 
== Step-By-Step Instructions: ==


== Tunnel A TCP Forward Port Through SSH ==
== Tunnel A TCP Forward Port Through SSH ==
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In this example '''SSH''' traffic is being '''NATed''' through a firewall. The '''SSH''' filtered port at the ''dirty'' side of the firewall is: "'''31222'''". We have chosen to use '''TCP''' port forwarding for the "'''''non-used'''''" '''TCP''' port: "'''9999'''". The remote '''NST''' probe's '''IP Address''' is: "'''55.44.22.178'''". On the ''local'' '''NST''' probe, '''TCP''' port: "'''9999'''" is bound to the '''localhost''' ('''IP Address''': "'''127.0.0.1'''").
In this example '''SSH''' traffic is being '''NATed''' through a firewall. The '''SSH''' filtered port at the ''dirty'' side of the firewall is: "'''31222'''". We have chosen to use '''TCP''' port forwarding for the "'''''non-used'''''" '''TCP''' port: "'''9999'''". The remote '''NST''' probe's '''IP Address''' is: "'''55.44.22.178'''". On the ''local'' '''NST''' probe, '''TCP''' port: "'''9999'''" is bound to the '''localhost''' ('''IP Address''': "'''127.0.0.1'''").


== Use: "'''nc'''" To Translate TCP To UDP On The SSH Server Side ==
== Use: "'''nc'''" To Translate TCP To UDP On The Remote SSH Server Side ==


On the remote '''NST''' probe ('''SSH''' server side), we need to open a port listener for '''TCP''' port: "'''9999'''" and translate all network traffic to '''UDP''' port: "'''623'''" for the '''IP Address''' assigned to the '''X4200''' server's '''ILOM''' network interface.
On the remote '''NST''' probe ('''SSH''' server side), we need to open a port listener for '''TCP''' port: "'''9999'''" and translate all network traffic to '''UDP''' port: "'''623'''" for the '''IP Address''' assigned to the '''X4200''' server's '''ILOM''' network interface.


We will first need to create a "'''[http://en.wikipedia.org/wiki/FIFO fifo]'''". The "'''[http://en.wikipedia.org/wiki/FIFO fifo]'''" will be necessary to maintain a two-way communication channel between the '''TCP''' port listener and the '''ILOM UDP''' port. A simple shell pipe would '''NOT''' work. It would only communicate left process' standard output to right process' standard input. We will use the '''Linux''' command: "'''[http://en.wikipedia.org/wiki/List_of_Unix_programs mkfifo]'''" to establish the "'''[http://en.wikipedia.org/wiki/FIFO fifo]'''".
We will first need to create a "'''[http://en.wikipedia.org/wiki/FIFO fifo]'''". The "'''[http://en.wikipedia.org/wiki/FIFO fifo]'''" will be necessary to maintain a two-way communication channel between the '''TCP''' port listener and the '''IPMI UDP''' port. A simple shell pipe would '''NOT''' work. It would only communicate left process' standard output to right process' standard input. We will use the '''Linux''' command: "'''[http://en.wikipedia.org/wiki/List_of_Unix_programs mkfifo]'''" to establish the "'''[http://en.wikipedia.org/wiki/FIFO fifo]'''".


<div class="screen">
<div class="screen">
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This command sequence will allow all '''TCP''' traffic on the remote '''NST''' probe for port: "'''9999'''" to be forwarded using the '''UDP''' network protocol to the '''X4200''' server's '''ILOM''' network interface: '''172.19.1.28''', '''UDP''' port: "'''623'''" and receive network traffic responses back.
This command sequence will allow all '''TCP''' traffic on the remote '''NST''' probe for port: "'''9999'''" to be forwarded using the '''UDP''' network protocol to the '''X4200''' server's '''ILOM''' network interface: '''172.19.1.28''', '''UDP''' port: "'''623'''" and receive network traffic responses back.
The diagram below is used to graphically demonstrate the two-way conversational flow at the remote '''NST''' probe using the "'''[http://en.wikipedia.org/wiki/FIFO fifo]'''" and '''TCP'''/'''UDP''' conversion using: "'''[http://en.wikipedia.org/wiki/Netcat nc]'''".
[[Image:Namedpipe.png|center|Named Pipe Diagram]]


== Use: "'''nc'''" To Translate UDP To TCP On The Local Side ==
== Use: "'''nc'''" To Translate UDP To TCP On The Local Side ==
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</div>
</div>


This command sequence will allow all '''UDP''' traffic on the local '''NST''' probe for port: "'''623'''" (the default '''ILOM UDP''' port value) to be forwarded using the '''TCP''' network protocol to the '''localhost''' ('''IP Address''': "'''127.0.0.1'''") listening '''TCP''' port: "'''9999'''" and receive network traffic responses back. The listening '''TCP IP:Port''': "'''127.0.0.1:9999'''" was established during the '''SSH''' setup above.
This command sequence will allow all '''UDP''' traffic on the local '''NST''' probe for port: "'''623'''" (the default '''IPMI UDP''' port value) to be forwarded using the '''TCP''' network protocol to the '''localhost''' ('''IP Address''': "'''127.0.0.1'''") listening '''TCP''' port: "'''9999'''" and receive network traffic responses back. The listening '''TCP IP:Port''': "'''127.0.0.1:9999'''" was established during the '''SSH''' setup above.


== Using the UDP Tunnel With "IPMItool" ==
== Using the UDP Tunnel With "IPMItool" ==


At this point the '''UDP''' tunnel is established through the '''SSH''' envelope to the remote '''ILOM''' on the '''X4200''' server. We will now demonstrate the use of the "'''[http://ipmitool.sourceforge.net/ IPMItool]'''" by issuing a "'''Fan Status'''" command through the '''UDP''' tunnel.
At this point the '''UDP''' tunnel is established through the '''SSH''' envelope to the remote '''ILOM''' on the '''X4200''' server. We will now demonstrate the use of the "'''[http://ipmitool.sourceforge.net/ IPMItool]'''" by issuing a '''IPMI''' "'''Fan Status'''" request command through the '''UDP''' tunnel on the local '''NST''' probe.


<div class="screen">
<div class="screen">
   <div class="screenTitle">FIFO Creation - Remote Side</div>
   <div class="screenTitle">IPMItool: "Sun Fire X4200 Fan Status"</div>
   <div class="userInput"><span class="prompt">[root@probe-biostar ~]# </span>/usr/bin/mkfifo "/tmp/fifo";</div>
   <div class="userInput"><span class="prompt">[root@probe tmp]# </span>/usr/local/bin/ipmitool -I lan -H 127.0.0.1 -p 623 -U root -P ********** sdr type 'Fan';</div>


     <pre class="computerOutput">
     <pre class="computerOutput">
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io.f0.speed      | 26h | ok  | 15.0 | 4200 RPM
io.f0.speed      | 26h | ok  | 15.0 | 4200 RPM
io.f0.fail      | 27h | ok  | 15.0 | Predictive Failure Deasserted
io.f0.fail      | 27h | ok  | 15.0 | Predictive Failure Deasserted
</pre><div class="userInput"><span class="prompt">[root@probe ~]# </span></div>
</pre><div class="userInput"><span class="prompt">[root@probe tmp]# </span></div>
</div>
</div>
The "'''[http://ipmitool.sourceforge.net/ IPMItool]'''" could also have been run from a browser attached to the '''NST WUI''' "'''[http://ipmitool.sourceforge.net/ IPMItool]'''" management interface page on the local '''NST''' probe.
== Summary ==
The '''IPMI''' "'''Fan Status'''" request initiated at a shell prompt on a local '''NST''' probe will be sent to '''UDP''' listening port: "'''127.0.0.1:623'''"  which will then be translated to '''TCP''' and forwarded to the '''TCP''' listening port: "'''127.0.0.1:9999'''". This traffic will be ''securely'' tunneled through an '''SSH''' connection which travels through a firewall using both '''NAT''' ('''N'''etwork '''A'''dress '''T'''ranslation) and '''PAT''' ('''P'''ort '''A'''ddress '''T'''ranslation) to a remote NST probe which is also listening on '''TCP''' port: "'''127.0.0.1:9999'''". The traffic is then translated back to '''UDP''' and '''finally''' forwarded and to the destination '''ILOM''' '''UDP''' listening port: "'''172.19.1.28:623'''" on the '''Sun Fire X4200''' server. The resultant information is sent in reverse order back as a response to the '''IPMI''' "'''Fan Status'''" request.
== An Alternative Tunnel: VPN - PPP Tunneled Over SSH ==
Please see the article: "'''[http://nst.sourceforge.net/nst/docs/user/ch07.html Using VPNs With NST]'''" on how to create alternate secure tunnels using '''NST''' and SSH connections.

Latest revision as of 07:46, 2 July 2008

Overview

This section describes how to use NST to tunnel a UDP network traffic conversation through an SSH connection. To demonstrate the effective use of UDP tunnelling, we will show how to remotely interrogate a Sun Fire X4200 server's Integrated Lights Out Manager (ILOM) service processor. The command line utility: "IPMItool" generates (UDP Port: "623") (IPMI - Intelligent Platform Management Interface) traffic which will travel through the SSH connection to the remote Sun Fire X4200 server's ILOM service processor network interface.

IPMI over LAN (i.e. a TCP/IP network) uses the Remote Management Control Protocol (RMCP) to support pre-OS and OS-absent management. RMCP is a request-response protocol using UDP datagrams on port: "623".

The network topology below depicts the three systems that are involved, 2 NST probes and one Sun Fire X4200 server. Reference information was taken from: "Performing UDP tunneling through an SSH connection".

Network Topology

Use this network topology as a reference for tunnelling UDP traffic through an SSH connection.

Network Topology
Network Topology

Step-By-Step Instructions:

Tunnel A TCP Forward Port Through SSH

First we need to establish the tunnel for a "non-used" TCP port from the local NST probe to the remote NST probe SSH server which shares the same LAN as the destination X4200 server.

Establish An SSH Connection With TCP Port Forwarding
[root@probe tmp]# /usr/bin/ssh -p 31222 -L 9999:localhost:9999 root@55.44.22.178;
root@55.44.22.178's password:
Last login: Thu Mar 22 11:18:59 2007 from cpe-72-222-76-188.nycaper.res.rdr.com

===============================================
= Linux Network Security Toolkit (NST v1.5.0) =
===============================================
[root@probe-biostar ~]#

In this example SSH traffic is being NATed through a firewall. The SSH filtered port at the dirty side of the firewall is: "31222". We have chosen to use TCP port forwarding for the "non-used" TCP port: "9999". The remote NST probe's IP Address is: "55.44.22.178". On the local NST probe, TCP port: "9999" is bound to the localhost (IP Address: "127.0.0.1").

Use: "nc" To Translate TCP To UDP On The Remote SSH Server Side

On the remote NST probe (SSH server side), we need to open a port listener for TCP port: "9999" and translate all network traffic to UDP port: "623" for the IP Address assigned to the X4200 server's ILOM network interface.

We will first need to create a "fifo". The "fifo" will be necessary to maintain a two-way communication channel between the TCP port listener and the IPMI UDP port. A simple shell pipe would NOT work. It would only communicate left process' standard output to right process' standard input. We will use the Linux command: "mkfifo" to establish the "fifo".

FIFO Creation - Remote Side
[root@probe-biostar ~]# /usr/bin/mkfifo "/tmp/fifo";
[root@probe-biostar ~]# /bin/ls -al "/tmp/fifo";
prw-r--r-- 1 root root 0 Mar 22 19:37 /tmp/fifo
[root@probe-biostar ~]#


Next we will use "nc" (netcat) the "TCP/IP Swiss Army Knife" to perform the TCP/IP to UDP translation.

TCP To UDP Network Traffic Translation Using: "nc"
[root@probe-biostar ~]# /usr/bin/nc -l 9999 < "/tmp/fifo" | /usr/bin/nc -u 172.19.1.28 623 > "/tmp/fifo";

This command sequence will allow all TCP traffic on the remote NST probe for port: "9999" to be forwarded using the UDP network protocol to the X4200 server's ILOM network interface: 172.19.1.28, UDP port: "623" and receive network traffic responses back.

The diagram below is used to graphically demonstrate the two-way conversational flow at the remote NST probe using the "fifo" and TCP/UDP conversion using: "nc".


Named Pipe Diagram
Named Pipe Diagram

Use: "nc" To Translate UDP To TCP On The Local Side

Once again we will need to create a "fifo" and use the "nc" networking utility for protocol translation. The following output shows the "fifo" creation on the local side where we will run the "IPMItool" command.

FIFO Creation - Local Side
[root@probe tmp]# /usr/bin/mkfifo "/tmp/fifo";
[root@probe tmp]# /bin/ls -al "/tmp/fifo";
prw-r--r-- 1 root root 0 Mar 22 19:37 /tmp/fifo
[root@probe tmp]#


Now perform the UDP to TCP/IP translation using: "nc".

UDP To TCP Network Traffic Translation Using: "nc"
[root@probe tmp]# /usr/bin/nc -l -u 623 < "/tmp/fifo" | /usr/bin/nc 127.0.0.1 9999 > "/tmp/fifo";

This command sequence will allow all UDP traffic on the local NST probe for port: "623" (the default IPMI UDP port value) to be forwarded using the TCP network protocol to the localhost (IP Address: "127.0.0.1") listening TCP port: "9999" and receive network traffic responses back. The listening TCP IP:Port: "127.0.0.1:9999" was established during the SSH setup above.

Using the UDP Tunnel With "IPMItool"

At this point the UDP tunnel is established through the SSH envelope to the remote ILOM on the X4200 server. We will now demonstrate the use of the "IPMItool" by issuing a IPMI "Fan Status" request command through the UDP tunnel on the local NST probe.

IPMItool: "Sun Fire X4200 Fan Status"
[root@probe tmp]# /usr/local/bin/ipmitool -I lan -H 127.0.0.1 -p 623 -U root -P ********** sdr type 'Fan';
sys.fanfail      | 04h | ok  | 23.0 | Predictive Failure Deasserted
ft0.fm0.fail     | 3Eh | ok  | 29.0 | Predictive Failure Deasserted
ft0.fm1.fail     | 3Fh | ok  | 29.1 | Predictive Failure Deasserted
ft0.fm2.fail     | 40h | ok  | 29.2 | Predictive Failure Deasserted
ft1.fm0.fail     | 41h | ok  | 29.3 | Predictive Failure Deasserted
ft1.fm1.fail     | 42h | ok  | 29.4 | Predictive Failure Deasserted
ft1.fm2.fail     | 43h | ok  | 29.5 | Predictive Failure Deasserted
ft0.fm0.f0.speed | 4Ah | ok  | 29.0 | 5400 RPM
ft0.fm2.f0.speed | 4Ch | ok  | 29.1 | 5600 RPM
ft0.fm1.f0.speed | 4Bh | ok  | 29.2 | 5400 RPM
ft1.fm0.f0.speed | 4Dh | ok  | 29.3 | 5600 RPM
ft1.fm1.f0.speed | 4Eh | ok  | 29.4 | 5600 RPM
ft1.fm2.f0.speed | 4Fh | ok  | 29.5 | 5900 RPM
io.f0.speed      | 26h | ok  | 15.0 | 4200 RPM
io.f0.fail       | 27h | ok  | 15.0 | Predictive Failure Deasserted
[root@probe tmp]#

The "IPMItool" could also have been run from a browser attached to the NST WUI "IPMItool" management interface page on the local NST probe.

Summary

The IPMI "Fan Status" request initiated at a shell prompt on a local NST probe will be sent to UDP listening port: "127.0.0.1:623" which will then be translated to TCP and forwarded to the TCP listening port: "127.0.0.1:9999". This traffic will be securely tunneled through an SSH connection which travels through a firewall using both NAT (Network Adress Translation) and PAT (Port Address Translation) to a remote NST probe which is also listening on TCP port: "127.0.0.1:9999". The traffic is then translated back to UDP and finally forwarded and to the destination ILOM UDP listening port: "172.19.1.28:623" on the Sun Fire X4200 server. The resultant information is sent in reverse order back as a response to the IPMI "Fan Status" request.


An Alternative Tunnel: VPN - PPP Tunneled Over SSH

Please see the article: "Using VPNs With NST" on how to create alternate secure tunnels using NST and SSH connections.

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