To track down a TLS setup problem with TN3270 and AT-TLS, I had to collect a System SSL Trace. You can collect data and have it output to the joblog, or the console. This is not good practice as it can produce a lot of output, and it is hard to read the data.
This blog post follows on from Collecting a TCPIP Packet trace on z/OS.
You can use the same CTRACE writer procedure for all your CTRACE work. It is better not to have more than one trace writing to it at a time.
Erik Janssen sent me an email on how to take the CTRACE file and process it in Wireshark. I’ve put his comments at the bottom.
You need to start the GSK Server task
See SSL Server task
My GSKSRVR JCL looks like
//GSKSRVR PROC REGSIZE=256M,OUTCLASS='A'
//*--------------------------------------------------------------------
//GO EXEC PGM=GSKSRVR,REGION=®SIZE,TIME=1440,
// PARM=('ENVAR("HOME=/etc/gskssl/server"),TERM(DUMP) X
// / 1>DD:STDOUT 2>DD:STDERR')
//STDOUT DD SYSOUT=&OUTCLASS,DCB=LRECL=250,
// FREE=END,SPIN=UNALLOC
//STDERR DD SYSOUT=&OUTCLASS,DCB=LRECL=250,
// FREE=END,SPIN=UNALLOC
//SYSOUT DD SYSOUT=&OUTCLASS,
// FREE=END,SPIN=UNALLOC
//CEEDUMP DD SYSOUT=&OUTCLASS,
// FREE=END,SPIN=UNALLOC
I did not change any parameters, or defaults.
Start it
s GSKSRVR
It gives
GSK01001I System SSL version 4.4, Service level OA59115.
GSK01003I SSL server initialization complete.
Within the TELNET (TN3270) parameters I had
TelnetParms ; ATTLS defined secure port TTLSPort 2023 ; DEBUG CONN DETAIL CTRACE DEBUG CONN trace CTRACE DEBUG TRACE CTRACE ConnType Secure ; Client chooses secure or nonsecure connection. EndTelnetParms
This limits the trace to only port 2023, other ports, such as 0023 were unaffected.
I set up parmlib member for GSK trace, member CPGSKON
TRACEOPTS
WTRSTART(ctwtr)
on
jobname(TCPIP)
wtr(ctwtr)
OPTIONS('LEVEL=255')
I turned trace on using
TRACE CT,ON,COMP=GSKSRVR,PARM=CTGSKON
This gave
IEE252I MEMBER CTGSKON FOUND IN USER.Z24C.PARMLIB
GSK01040I SSL component trace started.
ITT038I ALL OF THE TRANSACTIONS REQUESTED VIA THE TRACE CT COMMAND WERE SUCCESSFULLY EXECUTED.ITT110I INITIALIZATION OF CTRACE WRITER CTWTR COMPLETE.
The CTWTR procedure was started was part of this command.
You stop the trace with
trace CT,off,COMP=GSKSRVR
Wait for the message
ITT038I ALL OF THE TRANSACTIONS REQUESTED VIA THE TRACE CT COMMAND WERE SUCCESSFULLY EXECUTED.
And stop the CTWTR writer using
TRACE CT,WTRSTOP=CTWTR
You should get messages
ITT038I ALL OF THE TRANSACTIONS REQUESTED VIA THE TRACE CT COMMAND WERE SUCCESSFULLY EXECUTED.
IEE839I ST=(ON,0001M,00005M) AS=ON BR=OFF EX=ON MO=OFF MT=(ON,064K)
IEF196I AHL904I THE FOLLOWING TRACE DATASETS CONTAIN TRACE DATA :
IEF196I IBMUSER.CTRACE1
AHL904I THE FOLLOWING TRACE DATASETS CONTAIN TRACE DATA :
IBMUSER.CTRACE1ITT111I CTRACE WRITER CTWTR TERMINATED BECAUSE OF A WTRSTOP REQUEST.
If there is data in the file, you can use IPCS to format it.
The IPCS command is
CTRACE COMP(GSKSRVR) FULL ALL
You get output like
S0W1 MESSAGE 00000008 15:19:52.221020 SSL_INFO
Job TCPIP Process 0201003E Thread 00000001 read_v3_client_hello
Received CLIENT-HELLO message
S0W1 DUMP 00000020 15:19:52.221414 SSL_ASCII_DUMP
Job TCPIP Process 0201003E Thread 00000001 read_v3_client_hello
CLIENT-HELLO message
00000000: 010001FC 03030C33 81E156C3 DF4693DD *.......3..V..F..*
00000010: 621CA636 8A75BDF0 26F3DE8F 831B78BC *b..6.u..&.....x.*
...
S0W1 MESSAGE 00000008 15:19:52.226897 SSL_INFO
Job TCPIP Process 0201003E Thread 00000001 edit_ciphers
Using server certificate 'ZZZZ'
...
S0W1 MESSAGE 00000008 15:19:52.223132 SSL_INFO
Job TCPIP Process 0201003E Thread 00000001 read_v3_extended_client_hello
Elliptical curve 0030 is being skipped as it is only supported in TLS 1.3
Getting the data into Wireshark format.
Wireshark is an excellent tool for doing network trace, and decoding the flows. You can also is it to process the CTRACE data. Thanks for Eril Janssen for the instructions below on how to get from CTRACE to Wireshark.
You need to use the CTRACE SNIFFER option. This writes to the file with DDNAME of SNIFFER
Allocate a VB 1600 LRECL dataset and allocate it to a ddname, for example SNIFFER
ALLOC DD(SNIFFER) DS(<some dsname>) SHR
From IPCS you can now:
CTRACE COMP(SYSTCPDA) GMT SHORT OPTIONS((SNIFFER(1600,TCPDUMP) NOREASSEMBLY)) DS(‘<the trace ds>’)
The formatted trace will now be in <some dsname>. Do a binary transfer to your pc and you show be able to open the trace in wireshark.
I tend to use IPCS in batch (so I do not get the lock on the trace file, (grin)).
Problems
I was using CTRACE, the IPCS, then CTRACE etc. Sometimes the CTRACE writer would not start (or stop). This can be because you are still in IPCS, and IPCS has a lock on the dataset, or you have quit from IPCS, and TSO still has a lock on the data set. I used =X to get out of the ISPF session, and this usually freed it up.
I could it was easiest to run IPCS in batch – it saved lots of typing, and starting/stopping CTRACE when I had got it wrong.
There may still be a timing window, where the trace writer would not stop. When I stopped gsksrvr, the trace writer stopped.
ColinPaice 