rpcapd(8) System Manager's Manual rpcapd(8)
NAME
rpcapd - capture daemon to be controlled by a remote libpcap application
SYNOPSIS
rpcapd [ -b address ] [ -p port ] [ -4 ] [ -l host_list ]
[ -a host,port ] [ -n ] [ -v ] [ -d ] [ -i ]
[ -D ] [ -s config_file ] [ -f config_file ] [ -S ]
[ -K ssl_keyfile ] [ -X ssl_certfile ] [ -C ]
DESCRIPTION
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.
The client then sends the appropriate commands to rpcapd 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.
Configuration file
The user can create a configuration file in the same directory as the
executable, and put the configuration commands in there. In order for
rpcapd to execute the commands, it needs to be restarted on Win32, i.e.
the configuration file is parsed only at the beginning. The UNIX version
of rpcapd will reread the configuration file upon receiving a HUP signal.
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 desired flags plus -s filename. Rpcapd
will parse all the parameters and save them into the specified
configuration file.
Installing rpcapd on Win32
The remote daemon is installed automatically when installing WinPcap.
The installation process places the rpcapd executable 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.
Starting rpcapd on Win32
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.
Installing rpcapd on Unix-like systems
TBD
Starting rpcapd on Unix-like systems
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.
If your system supports systemd(1) and the corresponding rpcapd.socket
and rpcapd@.service service files have been installed, the rpcapd service
can be enabled by enabling the rpcapd.socket unit.
If your system supports launchd(8) and the org.tcpdump.rpcapd.plist file
has been installed, the rpcapd service can be enabled by loading the
org.tcpdump.rpcapd service.
If your system supports inetd(8) and the rpcapd.inetd.conf entry has been
added to inetd.conf(5), the rpcapd service can be enabled by telling
inetd to reread its configuration file.
If your system supports xinetd(8) and the rpcapd.xinetd.conf entry has
been added to xinetd.conf(5), the rpcapd service can be enabled by
telling xinetd to reread its configuration file.
OPTIONS
-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 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 flag is specified 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) and ignore all flags specified on
the command line.
-h Print this help screen.
If rpcapd was compiled with SSL support, the following options are also
available:
-S Require that SSL be used on connections.
-C With SSL enabled, XXX - I'm not sure how *fetching* the list of
compression mechanisms does anything to compression.
-S ssl_keyfile With SSL enabled, use ssl_keyfile as the SSL key file.
-X ssl_certfile With SSL enabled, use ssl_certfile as the SSL
certificate file.
SEE ALSO
pcap(3), rpcapd-config(5)
20 January 2023 rpcapd(8)
libpcap 1.10.4 - Generated Sat Apr 8 06:00:58 CDT 2023