Setting up Hercules networking with zOS under Linux (HowTo)

[ag5at]

This is the details of how I got Hercules and zOS TCPIP working on
Centos 5.2 Linux 64 bit.

I used the tap interface instead of tun because it SIMPLIFIES the
routing side of things.  This was particularly useful at work in my
Lab where I did not want to have to ask the network folks to propagate
another route.

All I needed was just an IP address on the subnet that the machine was
attached to.

From reading here and there I decided that we weren't going to be
using a CTC.  That would require all the routing and a small subnet
that I wanted to avoid.

So I created a new IODF with 2 3172 addresses at 0D20.  You can pick
any address you would like.  I will leave the details of that to the
reader.

Changes to the Hercules configuration file:

#       LCS

0D20.2 LCS 192.168.2.109


The following was the setup for my TCPIP.PARMLIB member
These are just lines out of it from the appropriate places, not the
whole member.  The '..' indicate missing lines

DEVICE  LCS1  LCS  D20  NONETMAN AUTORESTART
LINK    ETH1  ETHERNET  0  LCS1
..
..
HOME
  192.168.2.109    ETH1
..
BEGINRoutes
..
ROUTE 192.168.2.0/24            =            ETH1      MTU 1500
..
ROUTE DEFAULT                    192.168.2.1   ETH1     MTU DEFAULTSIZE
..
ENDRoutes
..
..
START LCS1

To make this easier, I got the hostcmd program from the files section
and assembled it and linked into a link list library (it needs to be
APF authorized, so you can stick it wherever you have an APF
authorized  library)  I chose to put it in the link list.  Remember
the SETCODE AC(1) in the lked step.

Next I created HERC1C member in SYS1.PROCLIB

//IEFPROC EXEC PGM=HOSTCMD,PARM='sh sudo ./echos.sh'

Ok, now we have gotten over all the Hercules/zOS stuff (That's the
easy part, if you are an MVS dude).

Now as you see we are going to be some 'sudoing' in linux, so add the
following to /etc/sudoers:

urid         ALL=(ALL)       NOPASSWD: ALL

Where "urid" is the UNIX id you are running hercules under.

In the directory where you start hercules from create the following:

echos.sh

#!/bin/bash
echo "1" >/proc/sys/net/ipv4/ip_forward
echo "1" >/proc/sys/net/ipv4/conf/eth0/proxy_arp
echo "1" >/proc/sys/net/ipv4/conf/tap0/proxy_arp

Now
chmod +x echos.sh

In the script you start hercules, add a line:

sudo chmod 666 /dev/net/tun

So my runz18 looks like:

#!/bin/bash
sudo chmod 666 /dev/net/tun
hercules -f conf/zos18.conf

Now more changes to your hercules conf file

#SHCMDOPT  NODIAG8
DIAG8CMD  ENABLE

I.E.  Make sure SHCMDOPT is the default and DIAG8 is turned on.

Now to attack hercules:

chmod chmod 6755 /usr/local/bin/hercifc

This allows hercifc to run as root so it can manipulate the TAP device

Now you can start hercules

./runz18

If you get the following message in your log, you have pretty much
everything on the UNIX side setup:

HHCLC073I 0D20: TAP device tap0 opened

Anything else, and there are permission issues somewhere

The devlist should look like

devlist 0d20

0:0D20 3088 LCS Port 00 IP (tap0) open

devlist 0d21
0:0D21 3088 LCS Port 00 IP (tap0) open

If you see something like
0:0D20 3088 LCS Port 00 IP ()

then all is not well permission wise and things WILL NOT work.


Ok,  IPL, etc.

Start net.
Start TCPIP
Once it comes up,

S HERC1C     or whatever you called it.

This will put cause hercules to execute the echos.sh script which will
set up all the goodies.  The reason that you have to do this after you
have started TCPIP is that the tap0/proxy_arp thingie doesn't exist
until all is opened up.

Good Luck

[Robin Atwood]

On Sunday 16 Nov 2008, August Treubig wrote:
> BEGINRoutes
> ..
> ROUTE 192.168.2.0/24            =            ETH1      MTU 1500
> ..
> ROUTE DEFAULT                    192.168.2.1   ETH1     MTU DEFAULTSIZE
> ..
> ENDRoutes

Thanks for the pointers, this was the part I had wrong, I should have used a
netmask.

> To make this easier, I got the hostcmd program from the files section
> and assembled it and linked into a link list library (it needs to be
> APF authorized, so you can stick it wherever you have an APF
> authorized  library)  

Using HOSTCMD is using a sledge-hammer to crack a nut! Simply add

net.ipv4.ip_forward = 1
net.ipv4.conf.eth0.proxy_arp = 1
to /etc/sysctl.conf on the host and

sh echo "1" >/proc/sys/net/ipv4/conf/tap0/proxy_arp
to your hercules.rc file.

HTH
--
------------------------------------------------------
Robin Atwood

[ag5at]

Robin,
Thanks for the ideas on the first two.  I am a Solaris guy and some
of the Linux things aren't the same.  

But having that said.  As I said in the original post, the
tap0/proxy_arp file does not appear until after TCPIP actually
opens the device.  

Your solution gets the following:

sh ./dofix.sh
HHCAO001I Hercules Automatic Operator thread started;
          tid=4221E940, pri=0, pid=30307
./dofix.sh: line 2: /proc/sys/net/ipv4/conf/tap0/proxy_arp: No such
file or directory
HHCPN013I EOF reached on SCRIPT file. Processing complete.

Even though the devlist shows:

devlist 0d20
0:0D20 3088 LCS Port 00 IP (tap0) open


August


--- In hercules-390@..., Robin Atwood <robin.atwood@...>
wrote:
>
> On Sunday 16 Nov 2008, August Treubig wrote:
> > BEGINRoutes
> > ..
> > ROUTE 192.168.2.0/24            =            ETH1      MTU 1500
> > ..
> > ROUTE DEFAULT                    192.168.2.1   ETH1     MTU
DEFAULTSIZE
> > ..
> > ENDRoutes
>
> Thanks for the pointers, this was the part I had wrong, I should
have used a

> netmask.
>
> > To make this easier, I got the hostcmd program from the files section
> > and assembled it and linked into a link list library (it needs to be
> > APF authorized, so you can stick it wherever you have an APF
> > authorized  library)  
>
> Using HOSTCMD is using a sledge-hammer to crack a nut! Simply add
>
> net.ipv4.ip_forward = 1
> net.ipv4.conf.eth0.proxy_arp = 1
> to /etc/sysctl.conf on the host and
>
> sh echo "1" >/proc/sys/net/ipv4/conf/tap0/proxy_arp
> to your hercules.rc file.
>
> HTH
> --
> ------------------------------------------------------
> Robin Atwood
>

[Robin Atwood]

On Thursday 20 Nov 2008, August Treubig wrote:

> But having that said.  As I said in the original post, the
> tap0/proxy_arp file does not appear until after TCPIP actually
> opens the device.
>
> Your solution gets the following:
>
> sh ./dofix.sh
> HHCAO001I Hercules Automatic Operator thread started;
>           tid=4221E940, pri=0, pid=30307
> ./dofix.sh: line 2: /proc/sys/net/ipv4/conf/tap0/proxy_arp: No such
> file or directory
> HHCPN013I EOF reached on SCRIPT file. Processing complete.
>
> Even though the devlist shows:
>
> devlist 0d20
> 0:0D20 3088 LCS Port 00 IP (tap0) open

Oh. that is not the case on my Linux system, you can write the file before
issuing the IPL command. I am using a .oat file but I doubt that makes a
difference. What level of kernel do you have on your host system?
--
------------------------------------------------------
Robin Atwood

[ag5at]

Centos Linux 5.2 x64 at

2.6.18-92.1.6.el5

Aug

--- In hercules-390@..., Robin Atwood <robin.atwood@...>
wrote:

>
> On Thursday 20 Nov 2008, August Treubig wrote:
> > But having that said.  As I said in the original post, the
> > tap0/proxy_arp file does not appear until after TCPIP actually
> > opens the device.
> >
> > Your solution gets the following:
> >
> > sh ./dofix.sh
> > HHCAO001I Hercules Automatic Operator thread started;
> >           tid=4221E940, pri=0, pid=30307
> > ./dofix.sh: line 2: /proc/sys/net/ipv4/conf/tap0/proxy_arp: No such
> > file or directory
> > HHCPN013I EOF reached on SCRIPT file. Processing complete.
> >
> > Even though the devlist shows:
> >
> > devlist 0d20
> > 0:0D20 3088 LCS Port 00 IP (tap0) open
>
> Oh. that is not the case on my Linux system, you can write the file

before
> issuing the IPL command. I am using a .oat file but I doubt that
makes a
> difference. What level of kernel do you have on your host system?
> --
> ------------------------------------------------------
> Robin Atwood
>

[Robin Atwood]

On Friday 21 Nov 2008, August Treubig wrote:
> Centos Linux 5.2 x64 at
>
> 2.6.18-92.1.6.el5

I am running 2.6.23 so I doubt that is the issue. I had another thought this
morning: are you pre-loading the tun module or does it load on demand?

Another tack would be to try to use the Herc auto-operator facility to issue
the echo when TCP/IP comes active.

HTH
--
------------------------------------------------------
Robin Atwood

[Roger Bowler]

--- In hercules-390@..., August Treubig wrote:
> the tap0/proxy_arp file does not appear until after TCPIP
> actually opens the device.  
> Your solution gets the following:
...
> /proc/sys/net/ipv4/conf/tap0/proxy_arp: No such file or directory

On Linux 2.4.18 it's the same. The tap0 device is not created until
the guest TCP/IP opens the adapter.

However, I found a tip in Jay Maynard's Share presentation at
http://linuxvm.org/Present/SHARE108/S2865jma.pdf :

echo "1" >/proc/sys/net/ipv4/conf/all/proxy_arp

or alternatively add this line to /etc/sysctl.conf :

net.ipv4.conf.all.proxy_arp = 1

This way you don't need to issue any extra commands after starting
Hercules.

Regards,
Roger Bowler
If it's "mainframe-like", it's not a mainframe!

[ag5at]

Roger,

Yes that does fix the problem.  So, I will rework my how to and re-put
it out.  

I also had a problem with issuing a diag 8 command when I tried to do
a "test" doing an attach of a device.  The machine took a machine
check. (That was interesting!).  But have not had any problems with
issuing the shell scripts doing the echo.



--- In hercules-390@..., "Roger Bowler" <rogerbowler@...>
wrote:

>
> --- In hercules-390@..., August Treubig wrote:
> > the tap0/proxy_arp file does not appear until after TCPIP
> > actually opens the device.  
> > Your solution gets the following:
> ...
> > /proc/sys/net/ipv4/conf/tap0/proxy_arp: No such file or directory
>
> On Linux 2.4.18 it's the same. The tap0 device is not created until
> the guest TCP/IP opens the adapter.
>
> However, I found a tip in Jay Maynard's Share presentation at
> http://linuxvm.org/Present/SHARE108/S2865jma.pdf :
>
> echo "1" >/proc/sys/net/ipv4/conf/all/proxy_arp
>
> or alternatively add this line to /etc/sysctl.conf :
>
> net.ipv4.conf.all.proxy_arp = 1
>
> This way you don't need to issue any extra commands after starting
> Hercules.
>
> Regards,
> Roger Bowler
> If it's "mainframe-like", it's not a mainframe!
>