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echoscu(1) OFFIS DCMTK echoscu(1)


echoscu - DICOM verification (C-ECHO) SCU


echoscu [options] peer port


The echoscu application implements a Service Class User (SCU) for the Verification SOP Class. It sends a DICOM C-ECHO message to a Service Class Provider (SCP) and waits for a response. The application can be used to verify basic DICOM connectivity.


peer  hostname of DICOM peer
port  tcp/ip port number of peer


general options

-h --help
print this help text and exit
print version information and exit
print expanded command line arguments
-q --quiet
quiet mode, print no warnings and errors
-v --verbose
verbose mode, print processing details
-d --debug
debug mode, print debug information
-ll --log-level [l]evel: string constant
(fatal, error, warn, info, debug, trace)
use level l for the logger
-lc --log-config [f]ilename: string
use config file f for the logger

network options

application entity titles:

-aet --aetitle [a]etitle: string
set my calling AE title (default: ECHOSCU)
-aec --call [a]etitle: string
set called AE title of peer (default: ANY-SCP) association negotiation debugging:
-pts --propose-ts [n]umber: integer (1..38)
propose n transfer syntaxes
-ppc --propose-pc [n]umber: integer (1..128)
propose n presentation contexts other network options:
-to --timeout [s]econds: integer (default: unlimited)
timeout for connection requests
-ts --socket-timeout [s]econds: integer (default: 60)
timeout for network socket (0 for none)
-ta --acse-timeout [s]econds: integer (default: 30)
timeout for ACSE messages
-td --dimse-timeout [s]econds: integer (default: unlimited)
timeout for DIMSE messages
-pdu --max-pdu [n]umber of bytes: integer (4096..131072)
set max receive pdu to n bytes (default: 16384)
--repeat [n]umber: integer
repeat n times
abort association instead of releasing it

transport layer security (TLS) options

transport protocol stack:

-tls --disable-tls
use normal TCP/IP connection (default)
+tls --enable-tls [p]rivate key file, [c]ertificate file: string
use authenticated secure TLS connection
+tla --anonymous-tls
use secure TLS connection without certificate private key password (only with --enable-tls):
+ps --std-passwd
prompt user to type password on stdin (default)
+pw --use-passwd [p]assword: string
use specified password
-pw --null-passwd
use empty string as password key and certificate file format:
-pem --pem-keys
read keys and certificates as PEM file (default)
-der --der-keys
read keys and certificates as DER file certification authority:
+cf --add-cert-file [f]ilename: string
add certificate file to list of certificates
+cd --add-cert-dir [d]irectory: string
add certificates in d to list of certificates
+crl --add-crl-file [f]ilename: string
add certificate revocation list file
(implies --enable-crl-vfy)
+crv --enable-crl-vfy
enable leaf CRL verification
+cra --enable-crl-all
enable full chain CRL verification security profile:
+py --profile-bcp195-nd
Non-downgrading BCP 195 TLS Profile (default)
+px --profile-bcp195
BCP 195 TLS Profile
+pz --profile-bcp195-ex
Extended BCP 195 TLS Profile
+pb --profile-basic
Basic TLS Secure Transport Connection Profile (retired)
+pa --profile-aes
AES TLS Secure Transport Connection Profile (retired)
+pn --profile-null
Authenticated unencrypted communication
(retired, was used in IHE ATNA) ciphersuite:
+cc --list-ciphers
show list of supported TLS ciphersuites and exit
+cs --cipher [c]iphersuite name: string
add ciphersuite to list of negotiated suites pseudo random generator:
+rs --seed [f]ilename: string
seed random generator with contents of f
+ws --write-seed
write back modified seed (only with --seed)
+wf --write-seed-file [f]ilename: string (only with --seed)
write modified seed to file f peer authentication:
-rc --require-peer-cert
verify peer certificate, fail if absent (default)
-ic --ignore-peer-cert
don't verify peer certificate offline certificate verification:
+vc --verify-cert [f]ilename: string
verify certificate against CA settings
# Load a client certificate and check whether it would be accepted
# when received during a TLS handshake. Print result and exit.
+rc --is-root-cert [f]ilename: string
check if certificate is self-signed root CA
# Load a client certificate and check whether it is a valid,
# self-signed root CA certificate. Print result and exit.


DICOM Conformance

The echoscu application supports the following SOP Classes as an SCU:

VerificationSOPClass                1.2.840.10008.1.1

Unless the --propose-ts option is used, the echoscu application will only propose the transfer syntax

LittleEndianImplicitTransferSyntax  1.2.840.10008.1.2


The level of logging output of the various command line tools and underlying libraries can be specified by the user. By default, only errors and warnings are written to the standard error stream. Using option --verbose also informational messages like processing details are reported. Option --debug can be used to get more details on the internal activity, e.g. for debugging purposes. Other logging levels can be selected using option --log-level. In --quiet mode only fatal errors are reported. In such very severe error events, the application will usually terminate. For more details on the different logging levels, see documentation of module 'oflog'.

In case the logging output should be written to file (optionally with logfile rotation), to syslog (Unix) or the event log (Windows) option --log-config can be used. This configuration file also allows for directing only certain messages to a particular output stream and for filtering certain messages based on the module or application where they are generated. An example configuration file is provided in <etcdir>/logger.cfg.


All command line tools use the following notation for parameters: square brackets enclose optional values (0-1), three trailing dots indicate that multiple values are allowed (1-n), a combination of both means 0 to n values.

Command line options are distinguished from parameters by a leading '+' or '-' sign, respectively. Usually, order and position of command line options are arbitrary (i.e. they can appear anywhere). However, if options are mutually exclusive the rightmost appearance is used. This behavior conforms to the standard evaluation rules of common Unix shells.

In addition, one or more command files can be specified using an '@' sign as a prefix to the filename (e.g. @command.txt). Such a command argument is replaced by the content of the corresponding text file (multiple whitespaces are treated as a single separator unless they appear between two quotation marks) prior to any further evaluation. Please note that a command file cannot contain another command file. This simple but effective approach allows one to summarize common combinations of options/parameters and avoids longish and confusing command lines (an example is provided in file <datadir>/dumppat.txt).


The echoscu utility uses the following exit codes when terminating. This enables the user to check for the reason why the application terminated.


EXITCODE_NO_ERROR                         0

input file errors


output file errors


network errors


(*) Actually, these codes are currently not used by echoscu but serve as a placeholder for the corresponding group of exit codes.


The echoscu utility will attempt to load DICOM data dictionaries specified in the DCMDICTPATH environment variable. By default, i.e. if the DCMDICTPATH environment variable is not set, the file <datadir>/dicom.dic will be loaded unless the dictionary is built into the application (default for Windows).

The default behavior should be preferred and the DCMDICTPATH environment variable only used when alternative data dictionaries are required. The DCMDICTPATH environment variable has the same format as the Unix shell PATH variable in that a colon (':') separates entries. On Windows systems, a semicolon (';') is used as a separator. The data dictionary code will attempt to load each file specified in the DCMDICTPATH environment variable. It is an error if no data dictionary can be loaded.


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Fri Apr 22 2022 Version 3.6.7