Getting TCPIP to talk to an ADCD system.

I had a new (z/OS 2.5) ADCD system, and wanted to get FTP working. Once I had unzipped the files, and started z/OS, I could not ping or connect to the z/OS via TCPIP.

When I wanted to use z/OS on a different machine I needed to configure my laptop to give the route to the machine using and Ethernet connection

sudo ip route add via 
# open a session to it
ssh -X colin@ 

Using my home wireless connection I could use instead

sudo ip route add dev wlp4s0
# open a session to it
ssh -X colin@ 

The problem

I had ZD&T running on my laptop; My definitions on Linux used an IP address of, but the the shipped ADCD system has been configured for a HOME entry of

You can either change z/OS, or you can change your Linux setup.

Changing z/OS

I wanted to get the address on my Linux to talk to z/OS, but z/OS was not configured for this address. Using the TCPIP command NETSTAT HOME showed it was configured for a .


; Destination        SubnetMask    FirstHop       LinkName    Size 
ROUTE    =            ETH1   MTU 1492 
; Destination                      First Hop      LinkName    Size 

The z/OS command D SYMBOLS gave

&DEFAULTROUTEADDR. = ""         
&DYNXCFIPADDRESS.  = ""        
&EPHEMERALPORTS.   = "10000 65534"        
&GBLRESL.          = "GBLRESOL"           
&TCPPROF.          = "PROF2"                            f

Updating the address

You have several approaches.

  • Update the system symbols and re-ipl or restart TCPIP
  • Replace the symbols with the hard coded definitions and re-ipl or restart TCPIP
  • Use system symbols and restart just the relevant bits of TCPIP
  • Update the TCPIP definitions and restart just the relevant bits of TCPIP

Update the system symbols and re-ipl

See Changing z/OS system symbols is – easy – ish.

My IEASYM definition included member IEASYMAU.

I created member USER.Z25A.PARMLIB(IEASYMAU), copied member FEU.Z25A.PARMLIB(IEASYMAU) into it, and changed the definitions.

        SYMDEF(&EPHEMERALPORTS.='10000 65534') 

I shutdown z/OS and restarted it – and then I could use PING and, once I had started FTPD, I could FTP to If you do not want to restart z/OS see below for the long story. in Changing z/OS system symbols is – easy – ish, or “Refreshing TCP/IP definitions“, below.

Update the TCPIP definitions and restart TCPIP or re-ipl

I backed up ADCD.Z25A.TCPPARMS(ZPDTDEV1), then changed ADCD.Z25A.TCPPARMS(ZPDTDEV1) to use the hardcoded address and default router address.

Restarting TCPIP or a REIPL activated these changes – but doing this is disruptive to users.

Refreshing TCP/IP definitions.

It is not easy to refresh the TCPIP definitions. See here.

Once I had made the changes, and activated the updated definitions, I could ping to z/OS and use FTPD.

Changing Linux

I changed my devmap to have

[manager] # tap0 define network adapter (OSA) for communication with Linux
name awsosa 0022 –path=A0 –pathtype=OSD –tunnel_intf=y –tunnel_ip=
device 400 osa osa –unitadd=0
device 401 osa osa –unitadd=1
device 402 osa osa –unitadd=2

The “ip route” command gave

default via dev wlp4s0 proto dhcp metric 600 dev wlp4s0 scope link metric 1000 dev tap0 proto kernel scope link src dev wlp4s0 proto kernel scope link src metric 600

The find_io command gave

         Interface         Current          MAC     IPv4       IPv6           
 Path    Name              State            Address Address    Address        
------   ----------------  ---------------- ------- -------    --------- 
  F0     enp0s31f6         UP, NOT-RUNNING  8c:...  *          *               
  F1     wlp4s0            UP, RUNNING      d4....  192....    2a00:...  
  F2     wwan0             DOWN             a2....  *          *               
  A0     tap0              UP, RUNNING      22.... fe80...
  A1     tap1              DOWN             02....  *         *               

I could ping and FTP to

4 thoughts on “Getting TCPIP to talk to an ADCD system.

  1. Hello Colin
    where do you find new (z/OS 2.5) ADCD ? I’m a mainframmer and would like to perform some test by using hercules + ADCD. However my ADCd is pretty old(zos 1.13) can not test some new features,for example zCX. If you can share the information I really appreciate it.

    Thanks and regards,



    1. Hi Michael,
      You need to purchase the zD&T/ZPDT package from IBM – for about £6000. You get the zPDT code, and the ADCD downloads. I do not think that ADCD is licensed to run on Hercules – I think OS/390 might be licensed – but I do not think z/OS is. A year or so ago someone told me z/OS does not run on Hercules ( or earlier versions of ZD&T) and program checks during IPL.


      1. Thank you for you reply Colin. That’s a really big cost for the individuals. IBM is seeking more mainframe users, however they didn’t wanna offer a reasonable price to promote ZD$T to involve rookies. What a joke. lol.

        Appreciate it!



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