Provided by: libcoap3-bin_4.3.4-1.1build4_amd64 
NAME
coap-client, coap-client-gnutls, coap-client-mbedtls, coap-client-openssl, coap-client-notls - CoAP
Client based on libcoap
SYNOPSIS
coap-client [-a addr] [-b [num,]size] [-e text] [-f file] [-l loss] [-m method] [-o file] [-p port] [-r]
[-s duration] [-t type] [-v num] [-w] [-A type] [-B seconds] [-E oscore_conf_file[,seq_file]] [-G count]
[-H hoplimit] [-K interval] [-L value] [-N] [-O num,text] [-P scheme://addr[:port]] [-T token] [-U] [-V
num] [-X size] [[-h match_hint_file] [-k key] [-u user]] [[-c certfile] [-j keyfile] [-n] [-C cafile] [-J
pkcs11_pin] [-M rpk_file] [-R trust_casfile]] URI
For coap-client versions that use libcoap compiled for different (D)TLS libraries, coap-client-notls,
coap-client-gnutls, coap-client-openssl, coap-client-mbedtls or coap-client-tinydtls may be available.
Otherwise, coap-client uses the default libcoap (D)TLS support.
DESCRIPTION
coap-client is a CoAP client to communicate with 6LoWPAN devices via the protocol CoAP (RFC 7252) using
the URI given as argument on the command line. The URI must have the scheme coap, coap+tcp, coaps or
coaps+tcp.
coaps and coaps+tcp are only supported when coap-client is built with support for secure (D)TLS
communication.
If coaps or coaps+tcp is being used, provided the CoAP server supports PKI and is configured with a
certificate and private key, the coap-client does not need to have a Pre-Shared Key (-k) or certificate
(-c) configured.
The URI’s host part may be a DNS name, a literal IP address or a Unix domain name. For Unix domain names,
%2F is used as the / separator to differentiate between the host and patch definitions. For IPv6 address
references, angle brackets are required (c.f. EXAMPLES) to delimit the host portion of the URI.
OPTIONS - GENERAL
-a addr
The local address of the interface that has to be used.
Note: Do not use this option if the interface is likely to be transient - i.e. it is a tunnel
interface that may come and go, as this is likely to cause "No such device" errors on transmission.
-b [num,]size
The block size to be used in GET/PUT/POST requests (value must be a multiple of 16 not larger than
1024 as libcoap uses a fixed maximum PDU size of 1400 bytes). If num is present, the request chain
will start at block num. When the server includes a Block2 option in its response to a GET request,
coap-client will automatically retrieve the subsequent block from the server until there are no more
outstanding blocks for the requested content.
-e text
Include text as payload (use percent-encoding for non-ASCII characters).
-f file
File to send with PUT/POST (use - for STDIN).
-l list
Fail to send some datagrams specified by a comma separated list of numbers or number ranges
(debugging only).
-l loss%
Randomly failed to send datagrams with the specified probability - 100% all datagrams, 0% no
datagrams (debugging only).
-m method
The request method for action (get|put|post|delete), default is get. (Note that the string passed to
-m is compared case-insensitive.)
-o file
A filename to store data retrieved with GET.
-p port
The port to send from.
-r
Use reliable protocol (TCP or TLS).
-s duration
Subscribe to / observe the resource specified by URI for the given duration in seconds.
-t type
Content format for given resource for PUT/POST. type must be either a numeric value reflecting a
valid CoAP content format or a string describing a registered format. The following registered
content format descriptors are supported, with alternative shortcuts given in parentheses:
text/plain (plain)
application/link-format (link, link-format)
application/xml (xml)
application/octet-stream (binary, octet-stream)
application/exi (exi)
application/json (json)
application/cbor (cbor)
-v num
The verbosity level to use (default 4, maximum is 8) for general CoAP logging.
-w
Append a newline to received data.
-A type
Accepted media type. type must be either a numeric value reflecting a valid CoAP content format or a
string that specifies a registered format as described for option -t.
-B seconds
Break operation after waiting given seconds (default is 90).
-E oscore_conf_file[,seq_file]
oscore_conf_file contains OSCORE configuration. See coap-oscore-conf(5) for definitions. Optional
seq_file (which is created if needed) is used to save the current transmit sequence number, so on
client restart sequence numbers continue to increase and are not reset to prevent anti-replay
mechanisms being triggered.
-G count
Repeat the Request count times with a second delay between each one. Must have a value between 1 and
255 inclusive. Default is 1.
-H hoplimit
Set the Hop Limit count to hoplimit for proxies. Must have a value between 1 and 255 inclusive.
Default is 16.
-K interval
Send a ping after interval seconds of inactivity. If not specified (or 0), keep-alive is disabled
(default).
-L value
Sum of one or more COAP_BLOCK_* flag values for different block handling methods. Default is 1
(COAP_BLOCK_USE_LIBCOAP).
COAP_BLOCK_USE_LIBCOAP 1
COAP_BLOCK_SINGLE_BODY 2
COAP_BLOCK_TRY_Q_BLOCK 4
COAP_BLOCK_USE_M_Q_BLOCK 8
COAP_BLOCK_NO_PREEMPTIVE_RTAG 16
-N
Send NON-confirmable message. If option -N is not specified, a confirmable message will be sent.
-O num,text
Add option num with contents of text to the request. If the text begins with 0x, then the hex text
(two [0-9a-f] per byte) is converted to binary data.
-P scheme://addr[:port]
Scheme, address and optional port to define how to connect to a CoAP proxy (automatically adds
Proxy-Uri option to request) to forward the request to. Scheme is one of coap, coaps, coap+tcp and
coaps+tcp.
-T token
Define the initial starting token for the request (up to 24 characters).
-U
Never include Uri-Host or Uri-Port options.
-V num
The verbosity level to use (default 3, maximum is 7) for (D)TLS library logging.
-X size
Maximum message size to use for TCP based connections (default is 8388864). Maximum value of 2^32 -1.
OPTIONS - PSK
(If supported by underlying (D)TLS library)
-h match_hint_file
This is a file that contains one or more lines of received Identity Hints to match to use different
user identity and associated pre-shared key (PSK) (comma separated) instead of the -k key and -u user
options. E.g., per line
hint_to_match,use_user,with_key
A line that starts with # is treated as a comment.
Note: -k key and -u user still need to be defined for the default case in case there is no match.
-k key
Pre-shared key for the specified user identity (-u option also required).
-u user
User identity to send for pre-shared key mode (-k option also required).
OPTIONS - PKI
(If supported by underlying (D)TLS library)
Note: If any one of certfile, keyfile or cafile is in PKCS11 URI naming format (pkcs11: prefix), then any
remaining non PKCS11 URI file definitions have to be in DER, not PEM, format. Otherwise all of certfile,
keyfile or cafile are in PEM format.
-c certfile
PEM file or PKCS11 URI for the certificate. The private key can also be in the PEM file, or has the
same PKCS11 URI. If not, the private key is defined by -j keyfile.
-j keyfile
PEM file or PKCS11 URI for the private key for the certificate in -c certfile if the parameter is
different from certfile in -c certfile.
-n
Disable remote peer certificate checking.
-C cafile
PEM file or PKCS11 URI for the CA certificate that was used to sign the server certfile. Ideally the
client certificate should be signed by the same CA so that mutual authentication can take place. The
contents of cafile are added to the trusted store of root CAs. Using the -C or -R options will
trigger the validation of the server certificate unless overridden by the -n option.
-J pkcs11_pin
The user pin to unlock access to the PKCS11 token.
-M rpk_file
Raw Public Key (RPK) PEM file or PKCS11 URI that contains both PUBLIC KEY and PRIVATE KEY or just EC
PRIVATE KEY. (GnuTLS and TinyDTLS(PEM) support only). -C cafile or -R trust_casfile are not
required.
-R trust_casfile
PEM file containing the set of trusted root CAs that are to be used to validate the server
certificate. Alternatively, this can point to a directory containing a set of CA PEM files. The -C
cafile CA does not have to be in this list and is trusted for the validation. Using -R trust_casfile
disables common CA mutual authentication which can only be done by using -C cafile. Using the -C or
-R options will will trigger the validation of the server certificate unless overridden by the -n
option.
EXAMPLES
• Example
coap-client coap://libcoap.net
Query the resource / from server libcoap.net (using the GET method).
• Example
coap-client -m get coap://[::1]/
Query the resource / on localhost using the GET method to get back the summary information.
• Example
coap-client -m get coap://%2Fsome%2Funix%2Fdomain%2Fpath/time
Query the resource /time on server listening on datagram Unix domain /some/unix/domain/path using the GET
method to get back the current time. The %2F is the hex encoding for / and indicates which is the host
definition separator and the simple / is for the path definition separator.
• Example
coap-client -m get coap://[::1]/.well-known/core
Query on the resource .well-known/core on localhost to get back a list of the known resources along with
their attribute definitions.
• Example
echo -n "mode=on" | coap-client -m put \
coap://[2001:db8:c001:f00d:221:2eff:ff00:2704]:5683/actuators/leds?color=r -f-
Send text mode=on to resource actuators/leds?color=r on the endpoint with address
2001:db8:c001:f00d:221:2eff:ff00:2704 and port 5683. Note that the port 5683 is the default port and
isn’t actually required in this instance.
• Example
coap-client -m put coap://[fec0::3]/ck -T 3a -t binary -f to_upload
Put the contents of file to_upload with content type binary (i.e. application/octet-stream) into resource
ck on fec0::3 using a token of 3a via the PUT method.
FILES
There are no configuration files.
EXIT STATUS
0
Success
1
Failure (syntax or usage error; configuration error; document processing failure; unexpected error)
SEE ALSO
coap-server(5) and coap-oscore-conf(5)
BUGS
Please report bugs on the mailing list for libcoap: libcoap-developers@lists.sourceforge.net or raise an
issue on GitHub at https://github.com/obgm/libcoap/issues
AUTHORS
The libcoap project <libcoap-developers@lists.sourceforge.net>
coap-client 4.3.4 04/15/2024 COAP-CLIENT(5)