The SSL certificate for https://midas.triumf.ca has been resigned with SHA256 to fix the complaint from google-chrome about SHA1-signed certificate - 
SHA1 signatures are now considered to be insufficiently secure, have to be replaced by SHA256.

The fingerprints for the new certificate are:
SHA256: 44:03:EA:FB:C5:83:24:01:23:7F:B6:4A:B3:87:A1:0C:98:6F:9F:1D:20:F4:3C:38:45:38:09:A4:6C:30:B9:4B
SHA1: 34:FB:6A:42:0D:92:D7:69:48:75:AD:FE:C8:1C:F7:B6:0B:07:1E:2F
MD5: C1 3D 99 50 13 81 19 FA 7E 65 60 4F F0 FC 99 EA

K.O.

> Is there currently an easy way to check from javascript if a midas client is running? I mean an equivalent 
to cm_exist.

Yes, I can add an ajax method for cm_exist. While at it, maybe ajax methods for starting and stopping 
clients - to permit fully ajaxed implementation of the "programs" page?

K.O.

(But only under the condition that you post elog messages in "plain" format - fancy formatted messages 
with highlighted word "very" show up as complete dog breakfast in my text based email. If you want to 
highlight something, just say "***!!!***very***!!!***", add more bangs to taste).

I am adding LZ4 and LZO compression the mlogger and as part of this work, I would like to add 
computation of checksums for the midas files.

On one side, such checksums help me confirm that uncompressed data contents is the same as original 
data (compression/decompression is okey).

On the other side, such checksums can confirm to the end user that today's contents of the midas file is 
the same as originally written by mlogger (maybe years ago) - there was no bit rot, no file corruption, no 
accidental or intentional modification of contents.

There are several choices of checksums available:
crc32 - as implemented by zlib (already written inside mid.gz files)
crc32c - improved and hardware accelerated version of CRC32 (http://tools.ietf.org/html/rfc3309)
md5 - cryptographically strong checksum, but obsolete
sha1 - same, also obsolete
sha256 - currently considered to be cryptographically strong

Of these checksums, only sha256 (sha512, etc) are presently considered to be cryptographically strong,
meaning that they can detect intentional file modifications. As opposed to (for example) crc32 where
it is easy to construct 2 files with different contents but the same checksum. Both md5 and sha1 are 
presently considered to be similarly cryptographically broken. But all of them are still usable
as checksums - as they will detect non-intentional data modifications (bit rot, etc) with
very high probability.

(Of course the strongest checksum is also the most expensive to compute).

I will probably implement crc32 (already in zlib), crc32c (easy to find hardware-accelerated
implementations) and sha256 (cryptographically strong).

I can write the computed checksums into midas.log, or into runNNN.crc32, runNNN.sha256, etc files. (or 
both).

Any thoughts on this?

K.O.

> > Any thoughts on this?
> 
> We use binary midas files now for ~20 years and never felt the necessity to put any checksums or even encryption on these files ...
>

"I have never seen a corrupted file, therefore nobody should ever need checksums". Well,

1) actually if you write mid.gz files, you get gzip checksums "for free" (but the checksums are not recorded anywhere, so 5 years later you cannot confirm that the file did not change).
2) I had a defective computer once where reading the same file several times yielded different data. (the defect was on the motherboard, not in the disks)
3) I am presently testing the btrfs filesystem which (like ZFS) keeps checksums for all data. For these tests I am using 3rd quality disks and I see btrfs regularly detect (and correct) "data corruption" events - where data on disk has changed.
4) there was a report from CERN(?) where they checked the checksums on a large number of data files and found a good number of corrupted files.

So bit rot does exist.

In more practical terms:

a) CRC32C is "free" to compute (hardware accelerated on latest CPUs), but does not detect malicious file modifications
b) SHA256 does detect that (but for how long?), but probably too expensive to compute (speed measurement TBD).
c) gzip compressed files have internal whole-file CRC32
d) bzip2 compressed files have internal per-block CRC32
e) lz4 compressed files have internal per-block xxhash checksums

Personally, when dealing with compressed files, I prefer to have a checksum recoded somewhere that I can check against after I decompress the file.

I think there is no need to add checksums to the MIDAS data files format itself (see c,d,e above).

K.O.

I updated the mhttpd HTTPS/SSL server (mongoose) and https://www.ssllabs.com/ssltest/index.html is 
now more or less happy with it. google chrome connects using "modern cryptography".

The HTTPS/SSL server is activated using "mhttpd --mg" (instead of -p) and it listens on port 8443.

The example SSL certificate provided in midas git is self-signed, for instructions on generating your own 
signed certificate, remove it and run "mhttpd --mg" - it will print the correct instructions.

List of corrected problems:
a) SSL certificate was generated with key length 1024 and SHA1 signature - should be 2048 and SHA256.
b) SSLv2, SSLv3 were not disabled per latest recommendations
c) RC4 and other weak ciphers were not disabled per latest recommendations
d) "modern cryptography" and "forward secrecy" were not available because they require special fondling of 
openssl.
e) on MacOS 10.9 *again* a whole bunch of openssl functions are listed as deprecated with no suggested 
replacement, there is a mismatch between system openssl and macports openssl and "modern 
cryptography" ECDH ciphers are not available.

Also to remember, mhttpd uses the latest release of mongoose 4.2 which is no longer supported by 
author. Latest version of mongoose is 5.x which has a severely improved API, but removed automatic 
multithreading.

I recommend that you use "mhttpd --mg" as the alternative for running "mhttpd -p" behind an apache 
proxy. Using "mhttpd -p" (no HTTPS/SSL) on an internet-connected machine is insecure and should not be 
done. (private network such as 192.168.x.y addresses is okey for now, I guess).

https://bitbucket.org/tmidas/midas/commits/d85ba733573f1fca9946804eeb71d6fdc23bea22

K.O.

> mhttpd uses the latest release of mongoose 4.2 which is no longer supported by 
> author. Latest version of mongoose is 5.x which has a severely improved API, but removed automatic 
> multithreading.

The exact version of mongoose 4.2 included with MIDAS is git revision 607651a3ffce43ef424530b22c7b1d22381de02d from 11 
November 2013.

https://github.com/cesanta/mongoose/commit/607651a3ffce43ef424530b22c7b1d22381de02d.

Documentation for this version of mongoose is committed to midas git repository .../midas/doc/mongoose.

K.O.

A set of improvements to mlogger is in:

a) event buffer (SYSTEM) size up to 2GB
b) test version of LZ4 high speed compression, support for bzip2 and pbzip2

Details:

a) previously contents of shared memory buffers (SYSTEM, SYSMSG, etc) were periodically saved to disk 
files SYSTEM.SHM, SYSMSG.SHM, etc. This was not workable for large event buffers - reading/writing 2GB 
of data takes quite some time. We have decided that saving buffer contents to disk is no longer necessary 
and ss_shm_close() no longer writes SYSTEM.SHM, SYSMSG.SHM, etc. From now on you will still see these 
files created, but size will be 0. The file ODB.SHM is not affected by this - ODB contents is saved to 
ODB.SHM via ss_shm_flush().

b) as a rework of mlogger file output drivers (using chainable c++ classes), test versions of new 
compression algorithms have been added. In the present test version, they are controlled by the value of 
"compression".

The plan is to ultimately have following outputs from the mlogger:

- ROOT output - save as before, but you have to use rmlogger executable
- FTP output - for high speed write over the network
- .mid output for uncompressed data
- .mid.gz - gzip1 compressed data - best compromise between compression ratio and speed - will be the 
new default
- .mid.bz2 via pbzip2 (parallel bzip2) - maximum compression ratio
- .mid.lz4 - lz4 compression for high speed data taking - maximum compression speed

The current test version implements the following selections of "compression":

80 - ROOT output through the new driver (use rmlogger executable)
98 - null output (no file written)
99 - uncompressed disk output
100 - lz4 comression
200 - piped bzip2 compression
201 - piped pbzip2 compression
300 - gzip compression
301 - gzip1 compression
309 - gzip9 compression

in addition the old selections are still available:
0 - uncompressed output
1 - gzip1 compression
9 - gzip9 compression

The final implementation will include a better way to configure the mlogger output channels.

K.O.

> > mhttpd uses the latest release of mongoose 4.2

mhttpd is now explicitly linked with OpenSSL to provide secure https connections via the mongoose web server.

a) google chrome reports "Your connection to ... is encrypted with modern cryptography." via TLS 1.2 and ECDHE ciphers
b) we believe there are no Linux systems that require running mhttpd and lack OpenSSL, but building mhttpd without OpenSSL is supported, see the cross 
compilation section in the Makefile.
c) MacOS comes with a very old version of OpenSSL. mhttpd will build, https will work, but with a complaint about "obsolete cryptography". Please install an up-to-
date OpenSSL package via macports.
d) security of OpenSSL itself is quite problematic, please keep an eye open on OpenSSL security advisories, update OpenSSL and restart/rebuild mhttpd promptly. I 
expect the mongoose project to eventually switch from OpenSSL to one of the new-generation TLS libraries, such as PolarSSL (embed_tls) and we will follow their 
lead.

K.O.

ROOT support in MIDAS is being reworked:

a) ROOT support moved from midas.h to rmidas.h
b) default mlogger is built without ROOT support, use rmlogger if you need ROOT output
c) Makefile inconsistency between use of ROOTSYS and use of root-config has been identified, but not yet 
fixed. the plan is to use root-config to detect and use the ROOT package.
d) cross compilation will not support ROOT (same as now. "make linux32", "make linux64", "make 
linuxarm" disable most optional packages. To build full featured midas with ROOT & etc please compile 
natively on the ARM machine).
e) histogram servers in MIDAS and ROOTANA will be switched to use the new ROOT Web server classes 
(based on "civet", a fork of the mongoose web server).

K.O.

Latest C/C++ compilers (MacOS 10.10, GCC on RHEL7 and Ubuntu) generate a large number of new 
warnings about unused variables, unused functions, dead code, failure to check return values of system 
calls, etc.

Some of these warnings catch real bugs so we do not want to turn them off.

Most of these warnings have been cleaned out in the latest MIDAS code. On MacOS and RHEL6 Linux MIDA 
S compiles without any warnings. On RHEL7 and Ubuntu Linux there are some warnings from a few 
problematic files, history.c being the worst (it will be eventually cleaned out).

K.O.

> ROOT support in MIDAS is being reworked:
>
> c) Makefile inconsistency between use of ROOTSYS and use of root-config has been identified,

MIDAS Makefile was corrected to use root-config exclusively to find and use ROOT. This makes us more consistent
with the ROOT-recommended use of the thisroot.{sh,csh} scripts.

In other words, if root-config is in the PATH, ROOT support will be enabled, rmlogger and rmana.o will be built.

To explicitly disable ROOT, say "make NO_ROOT=1"

K.O.

> > ROOT support in MIDAS is being reworked:
> >
> > c) Makefile inconsistency between use of ROOTSYS and use of root-config has been identified,
> 
> MIDAS Makefile was corrected to use root-config exclusively to find and use ROOT. This makes us more consistent
> with the ROOT-recommended use of the thisroot.{sh,csh} scripts.
> 

The updated ROOT instructions on DAQwiki
https://www.triumf.info/wiki/DAQwiki/index.php/ROOT
now explain how to use "thisroot" to select the right version of the package.

The preliminary version of the .bashrc blurb looks like this
(a couple of flaws:
1) identification of CentOS7 is incomplete - please send me a patch
2) there should be a check for root-config already in the PATH, as on Ubuntu, the ROOT package may be installed in /usr and root-
config may be already in the path - please send me patch).

if [ `uname -i` == "i386" ]; then 
    . /daq/daqshare/olchansk/root/root_v5.34.01_SL62_32/bin/thisroot.sh 
    true 
elif [ `lsb_release -r -s` == "7.1.1503" ]; then 
    #. /daq/daqshare/olchansk/root/root_v5.34.32_SL66_64/bin/thisroot.sh 
    true 
else 
     . /daq/daqshare/olchansk/root/root_v5.34.32_SL66_64/bin/thisroot.sh 
     true 
fi 

K.O.

> A set of improvements to mlogger is in:
> b) test version of LZ4 high speed compression, support for bzip2 and pbzip2

rootana TMidasFile now supports reading .mid.lz4 compressed files via pipe through the "lz4" utility ("yum install lz4", "apt-get install liblz4-tool").

In MIDAS, the lz4 libraries are included with the MIDAS distribution, we are considering the same for ROOTANA.

(Support for reading mid.bz2 files via pipe through the bzip2 utility existed for a very long time).

https://bitbucket.org/tmidas/rootana/commits/e06bb7296a466b4178c7768bbc2470be361b2c72

K.O.

> A set of improvements to mlogger is in:
> The current test version implements the following selections of "compression":
> 
> 80 - ROOT output through the new driver (use rmlogger executable)
> ...

Additional output modes through the new output drivers:

81 - FTP output
82 - FTP output with LZ4 compression

The format of the "Channels/xxx/Settings/Filename" for FTP output is like this:
"/localhost, 5555, ftpuser, ftppwd, ., run%05dsub%05d.mid"

- the leading slash is required (for now)
- localhost is the FTP server hostname
- 5555 is the FTP server port number
- ftpuser and ftppwd are the FTP login. password is stored and transmitted in clear text for extra security
- "." is the output directory on the FTP server
- the rest is the file name in the usual format.

For testing this driver, I run the ftp server like this:

# vsftpd -olisten=YES -obackground=no -olisten_port=5555 -olisten_address=127.0.0.1 -oport_promiscuous=yes -oconnect_from_port_20=no -oftp_data_port=6666

K.O.

The define for MAX_EVENT_SIZE was removed from midas.h.

Replacing it is DEFAULT_MAX_EVENT_SIZE set to 4 MiBytes and DEFAULT_BUFFER_SIZE 
set to 32 MiBytes.

For a long time now MIDAS does not have hardcoded maximum event size and buffer size 
and this change merely renames the define to reflect it's current function.

The actual maximum event size is set by ODB /Experiment/MAX_EVENT_SIZE.

The actual event buffer sizes are set by ODB "/Experiment/Buffer sizes/SYSTEM" & co

K.O.

There is a number of problems with network security in midas. (as separate from web/http/https security).

1) too many network sockets are unnecessarily bound to the external network interface instead of localhost (UDP ports are already bound to localhost on MacOS).
2) by default the RPC ports of each midas program accept connections and RPC commands from anywhere in the world (an access control list is already implemented via /Experiment/Security/Rpc Hosts, but not active by default)
3) mserver also has an access control list but it is not integrated with the access control list for the RPC ports.
4) it is difficult to run midas in the presence of firewalls (midas programs listen on random network ports - cannot be easily added to firewall rules)

There is a new git branch "feature/rpcsecurity" where I am addressing some of these problems:

1) UDP sockets are only used for internal communications (hotlinks & etc) within one machine, so they should be bound to the localhost address and become invisible to external machines. This change breaks binary compatibility from old clients - they are have to be relinked with the new midas library or hotlinks & etc will stop working. If some clients cannot be rebuild (I have one like this), I am preserving the old way by checking for a special file in the experiment directory (same place as ODB.SHM). (done)

2) if one runs on a single machine, does not use the mserver and does not have clients running on other machines, then all the RPC ports can be bound to localhost. (this kills the MacOS popups about "odbedit wants to connect to the Internet"). (partially done)

This (2) will become the new default - out of the box, midas will not listen to any external network connections - making it very secure.

To use the mserver, one will have to change the ODB setting "/Experiment/Security/Enable external RPC connections" and restart all midas programs (I am looking for a better name for this odb setting).

3) the out-of-the-box default access control list for RPC connections will be set to "localhost", which will reject all external connections, even when they are enabled by (2). One will be required to enter the names of all machines that will run midas clients in "/Experiment/Security/Rpc hosts". (already implemented in main midas, but default access control list is empty meaning everybody is permitted)

4) the mserver will be required to attach to some experiment and will use this same access control list to restrict access to the main mserver listener port. Right now the mserver listens on this port without attaching to any experiment and accepts the access control list via command line arguments. I think after this change a single mserver will still be able to service multiple experiments (TBD).

5) I am adding an option to fix TCP port numbers for MIDAS programs via "/Experiment/Security/Rpc ports/fename = (int)5555". Once a remote frontend is bound to a fixed port, appropriate openings can be made in the firewall, etc. Default port number value will be 0 meaning "use random port", same as now.

One problem remains with initial connecting to the mserver. The client connects to the main mserver listener port (easy to firewall), but then the mserver connects back to the client - this reverse connection is difficult to firewall and this handshaking is difficult to fix in the midas sources. It will probably remain unresolved for now.

K.O.

There is a number of problems with network security in midas. (as separate from 
web/http/https security).

1) too many network sockets are unnecessarily bound to the external network interface 
instead of localhost (UDP ports are already bound to localhost on MacOS).
2) by default the RPC ports of each midas program accept connections and RPC commands 
from anywhere in the world (an access control list is already implemented via 
/Experiment/Security/Rpc Hosts, but not active by default)
3) mserver also has an access control list but it is not integrated with the access control list 
for the RPC ports.
4) it is difficult to run midas in the presence of firewalls (midas programs listen on random 
network ports - cannot be easily added to firewall rules)

There is a new git branch "feature/rpcsecurity" where I am addressing some of these 
problems:

1) UDP sockets are only used for internal communications (hotlinks & etc) within one 
machine, so they should be bound to the localhost address and become invisible to external 
machines. This change breaks binary compatibility from old clients - they are have to be 
relinked with the new midas library or hotlinks & etc will stop working. If some clients cannot 
be rebuild (I have one like this), I am preserving the old way by checking for a special file in 
the experiment directory (same place as ODB.SHM). (done)

2) if one runs on a single machine, does not use the mserver and does not have clients 
running on other machines, then all the RPC ports can be bound to localhost. (this kills the 
MacOS popups about "odbedit wants to connect to the Internet"). (partially done)

This (2) will become the new default - out of the box, midas will not listen to any external 
network connections - making it very secure.

To use the mserver, one will have to change the ODB setting "/Experiment/Security/Enable 
external RPC connections" and restart all midas programs (I am looking for a better name for 
this odb setting).

3) the out-of-the-box default access control list for RPC connections will be set to 
"localhost", which will reject all external connections, even when they are enabled by (2). One 
will be required to enter the names of all machines that will run midas clients in 
"/Experiment/Security/Rpc hosts". (already implemented in main midas, but default access 
control list is empty meaning everybody is permitted)

4) the mserver will be required to attach to some experiment and will use this same access 
control list to restrict access to the main mserver listener port. Right now the mserver listens 
on this port without attaching to any experiment and accepts the access control list via 
command line arguments. I think after this change a single mserver will still be able to service 
multiple experiments (TBD).

5) I am adding an option to fix TCP port numbers for MIDAS programs via 
"/Experiment/Security/Rpc ports/fename = (int)5555". Once a remote frontend is bound to a 
fixed port, appropriate openings can be made in the firewall, etc. Default port number value 
will be 0 meaning "use random port", same as now.

One problem remains with initial connecting to the mserver. The client connects to the main 
mserver listener port (easy to firewall), but then the mserver connects back to the client - this 
reverse connection is difficult to firewall and this handshaking is difficult to fix in the midas 
sources. It will probably remain unresolved for now.

K.O.

New git branch "feature/rpcsecurity" implements  these security features:

- all UDP ports are bound to the localhost interface - connections from outside are not possible
- by default out of the box MIDAS RPC TCP ports are bound to the localhost interface - connections from the outside are not possible.

This configuration is suitable for testing MIDAS on a laptop and for running a simple experiment where all programs run on one machine.

This configuration is secure (connections from the outside are not possible).

This configuration makes corporate security people happy - MIDAS ports do not show up on network port scans (nmap & etc). (except for the mhttpd 
web ports).

The change in binding UDP ports is incompatible with previous versions of MIDAS (except on MacOS, where UDP ports were always bound to localhost). 
All MIDAS programs should be rebuild and restarted, otherwise ODB hotlinks and some other stuff will not work. If rebuilding all MIDAS programs is 
impossible (for example I have one magic MIDAS frontend that cannot be rebuilt), one can force the old (insecure) behavior by creating a file 
.UDP_BIND_HOSTNAME in the experiment directory (next to .ODB.SHM).

The mserver will still work in this localhost-restricted configuration - one should use "odbedit -h localhost" to connect. Multiple mserver instances on 
the same machine - using different TCP ports via "-p" and ODB "/Experiment/midas server port" - are still supported.

To run MIDAS programs on remote machines, one should change the ODB setting "/Experiment/Security/Enable non-localhost RPC" to "yes" and 
add the hostnames of all remote machines that will run MIDAS programs to the MIDAS RPC access control list in ODB "/Experiment/Security/RPC hosts".

To avoid "guessing" the host names expected by MIDAS, do this: set "enable non-localhost rpc" to "yes" and restart the mserver. Then go to the remote 
machine and try to start the MIDAS program, i.e. "odbedit -h daq06". This will bomb and there will be a message in the midas log file saying - rejecting 
connection from unallowed host 'ladd21.triumf.ca'. Add this host to "/Experiment/Security/RPC hosts". After you add this hostname to "RPC hosts" and 
restart the mserver, the connection should be successful. When "RPC hosts" is fully populated, one should restart all midas programs - the access 
control list is only loaded at program startup.

If MIDAS clients have to connect from random hosts (i.e. dynamically assigned random DHCP addresses), one can disable the host name checks by 
setting ODB "/experiment/security/Disable RPC hosts check" to "yes". This configuration is insecure and should only be done on a private network 
behind a firewall.

After some more testing this branch will be merged into the main midas.

K.O.

> Hello, I am new in the forum. We are running an experiment for a week with no
> problems. Now we add a detector a we found an error. Even we come back to our
> previous configuration the error continues appearing. Please, may someone help
> us? You can find the error in the attachment. Thanks!

The error reported is SIGSEGV, which is a software fault (as opposed to a hardware fault like "printer is on fire" or "disk full").

Next step is to identify which program crashed and attach a debugger to the crashing executable or to the core dump.
You will use the debugger to generate the stack trace which will identify exactly the place where the program failed.

I recommend that one should always attach the stack trace to the problem reports on this forum. These stack traces are sometimes long and 
scary and it is a bit of an art to read them, so do not worry if you do not understand what they say.

If you use "gdb", I recommend that you post your full debugger session:

bash> gdb myprogram
gdb> run my command line arguments
*crash*
gdb> where
... stack trace
gdb> quit

(If you use threads, please generate a stack trace for each thread)

If the crash location is inside midas code, congratulations, you may have found a bug in midas.
If the crash location is in your code, you have some debugging to do.
If you do not understand what I am talking about (gdb? core dump?), please read "unix/linux software development for dummies" book first.

K.O.

> A set of improvements to mlogger is in:

Preliminary support for CRC32-zlib, CRC32C, SHA-256 and SHA-512 is in. Checksums are computed correctly, but plumbing configuration is 
preliminary. Good enough for testing and benchmarking.

To enable checksums, set channel compression:
100 - no checksum (LZ4 compression)
11100 - CRC32-zlib checksum
22100 - CRC32C
33100 - SHA-256
44100 - SHA-512
checksums for both uncompressed and compressed data will be computed and reported into midas.log.

To compare:

CRC32-zlib is for compatibility with gzip and zlib tools
CRC32C is for maximum speed
SHA-256 and SHA-512 is for maximum data security

To remember:

- CRC32-zlib is the CRC32 computation from gzip/png/zlib library. I believe the technical name of the algorithm is "adler32".
- CRC32C is the most recently improved version of CRC32 family of checksums. Implementation is from Mark Adler (same Adler as adler32) uses 
hardware acceleration on recent Intel CPUs.
- SHA-256 and SHA-512 are checksums currently accepted as cryptographically secure. One of them is supposed to be faster on 64-bit 
machines. I implement both for benchmarking.

"Cryptographically secure" means "nobody has a practical way to construct two different files with the same checksum".

In simpler words, the file contents cannot change without breaking the checksum - by software bug, by hardware fault, by benign or malicious 
intent.

The CRC family of checksum functions were never cryptographically secure.
MD5 and SHA-1 used to be secure but are no longer considered to be so. MD5 was definitely broken as different files with the same checksum 
have been discovered or constructed.

K.O.