rpcapd - capture daemon to be controlled by a remote libpcap application
rpcapd [ -b address ] [ -p port ] [ -4 ] [
-l host_list ]
[ -a host,port ] [ -n ] [ -v ] [ -d ]
[ -i ]
[ -D ] [ -s config_file ] [ -f config_file ]
Rpcapd is a daemon (Unix) or service (Win32) that allows the capture and
filter part of libpcap to be run on a remote system.
Rpcapd can run in two modes: passive mode (default) and active
mode.
In passive mode, the client (e.g., a network sniffer) connects to
rpcapd. It then sends hem the appropriate commands to start the
capture.
In active mode, rpcapd tries to establish a connection
toward the client (e.g., a network sniffer). The client then sends the
appropriate commands to rpcapd to start the capture.
Active mode is useful in case rpcapd is run behind a
firewall and cannot receive connections from the external world. In this
case, rpcapd can be configured to establish the connection to a given
host, which has to be configured in order to wait for that connection. After
establishing the connection, the protocol continues its job in almost the
same way in both active and passive mode.
The user can create a configuration file in the same folder of the executable,
and put the configuration commands in there. In order for rpcapd to execute
the commands, you have to restart it on Win32, i.e. the initialization file is
parsed only at the beginning). The UNIX version of rpcapd will reread the
configuration file when receiving a HUP signel. In that case, all the existing
connections remain in place, while the new connections will be created
according to the new parameters.
In case a user does not want to create the configuration file
manually, they can launch rpcapd with the requested parameters plus "-s
filename". Rpcapd will parse all the parameters and save them into the
specified configuration file.
The remote daemon is installed automatically when installing WinPcap. The
installation process places the rpcapd file into the WinPcap folder. This file
can be executed either from the command line, or as a service. For instance,
the installation process updates the list of available services list and it
creates a new item (Remote Packet Capture Protocol v.0 (experimental) ). To
avoid security problems, the service is inactive and it has to be started
manually (control panel - administrative tools - services - start).
The service has a set of "standard" parameters, i.e. it
is launched with the -d flag (in order to make it run as a service)
and the -f rpcapd.ini flag.
The rpcapd executable can be launched directly, i.e. it can run in the
foreground as well (not as a daemon/service). The procedure is quite simple:
you have to invoke the executable from the command line with all the requested
parameters except for the -d flag. The capture server will start in the
foreground.
rpcapd needs sufficient privileges to perform packet capture, e.g. run as
root or be owned by root and have suid set. Most operating systems provide
more elegant solutions when run as user than the above solutions, all of them
different.
- -b address
- Bind to the IP address specified by address (either numeric or
literal). By default, rpcapd binds to all local IPv4 and IPv6
addresses.
- -p port
- Bind to the port specified by port. By default, rpcapd binds
to port 2002.
- -4
- Listen only on IPv4 addresses. By default, rpcapd listens on both
IPv4 and IPv6 addresses.
- -l host_list
- Only allow hosts specified in the host_list argument to connect to
this server. host_list is a list of host names or IP addresses,
separated by commas. We suggest that you use use host names rather than
literal IP addresses in order to avoid problems with different address
families.
- -n
- Permit NULL authentication (usually used with -l).
- -a host,port
- Run in active mode, connecting to host host on port port. In
case port is omitted, the default port (2003) is used.
- -v
- Run in active mode only; by default, if -a is specified,
rpcapd it accepts passive connections as well.
- -d
- Run in daemon mode (UNIX only) or as a service (Win32 only) Warning
(Win32): this switch is provided automatically when the service is started
from the control panel.
- -i
- Run in inetd mode (UNIX only).
- -D
- Log debugging messages.
- -s config_file
- Save the current configuration to config_file in the format
specified by rpcapd-config(5).
- -f config_file
- Load the current configuration from config_file in the format
specified by rpcapd-config(5); all switches specified from the
command line are ignored.
- -h
- Print this help screen.
pcap(3), rpcapd-config(5)