tcpspy - TCP/IP Connection Monitor
tcpspy [-dp] [-e rule]... [-f rulefile]... [-F facility] [-I
interval] [-U user] [-G group]
tcpspy logs information about selected incoming and outgoing TCP/IP
connections to syslog. The following information is logged: username,
local address and port, remote address, port, and optionally the
filename of the executable. At present, only the IPv4 protocol is
Log only connections matching the specified rule. Rule syntax is
outlined below. If this option is specified more than once,
connections matching any of the specified rules are logged. You
should quote the rule, as shown above.
Read rules from rulefile. Each rule is on a new line. The ‘#’
character may be used to add comments; everything from this
character to the end of the line is ignored.
The -e and -f options may be used together.
Log to syslog facility facility instead of the compile-time
default setting. See the syslog.conf(5) manual page for a list
Update the internal state every interval milliseconds, instead
of the default of 1000 ms. Connections that last less than
interval milliseconds may be missed, so you should experiment to
find a value small enough that it catches most connections, but
not so small that it causes tcpspy to use too much CPU time.
Switch to the specified user after startup. user may be a
numeric user id or a user name from the system password file.
Switch to the specified group after startup. group may be a
numeric group id or a group name from the system group file. If
a username to switch to with the -U option is specified but -G
is omitted, tcpspy will switch to that specified user’s primary
-d Debugging mode; if this option is specified, tcpspy will not
detach from the console after initialisation, and will log
connections to standard output instead of syslog.
-p Log the filename of the executable that created/accepted the
connection. You may require superuser privileges to obtain this
information for processes you do not own (this is a kernel
This option can greatly increase the amount of CPU time required
to process each connection/disconnection.
A rule may be specified with the -e option to log information about
connections matching this rule, overriding the default of logging all
The following comparison operations are defined:
True if the local user initiating or accepting the connection
has the effective user id uid.
Same as above, but using a username instead of a user id.
True if the local end of the connection has port number port.
lport [low] - [high]
True if the local end of the connection has a port number
greater than or equal to low and less than or equal to high. If
the form low- is used, high is assumed to be 65535. If the form
-high is used, low is assumed to be 0. It is an error to omit
both low and high.
Same as above, but using a service name from /etc/services
instead of a port number.
rport Same as lport but compares the port number of the remote end of
Interpreted as a "net/mask" expression; true if "net" is equal
to the bitwise AND of the local address of the connection and
"mask". If no mask is specified, a default mask with all bits
set (255.255.255.255) is used.
raddr Same as laddr but compares the remote address.
True if the full filename (including directory) of the
executable that created/accepted the connection matches pattern,
a glob(7)-style wildcard pattern.
The pattern "" (an empty string) matches connections
created/accepted by processes whose executable filename is
If the -p option is not specified, a warning message will be
printed, and the result of this comparison will always be true.
Expressions (including the comparisons listed above) may be joined
together with the following logical operations:
expr1 or expr2
True if either of expr1 or expr2 are true (logical OR).
expr1 and expr2
True if both expr1 and expr2 are true (logical AND).
True if expr is false (logical NOT).
Rules are evaluated from left to right. Whitespace (space, tab and
newline) characters are ignored between "words". Rules consisting of
only whitespace match no connections, but do not cause an error.
Parentheses, ’(’ and ’)’ may be placed around expressions to affect the
order of evaluation.
The Examples section contains some sample rules which further
demonstrate how they are constructed.
0 The daemon was successfully started
>0 An error occurred
TERM Shut down at most interval milliseconds from now.
INT (Debugging mode only) Handled identically to TERM.
All other signals retain their default behaviour, which is documented
tcpspy -e ’user "joe" and rport "ssh"’
Log connections made by user "joe" for the service "ssh".
tcpspy -e ’not raddr 10.0.0.0/255.0.0.0 and rport 25 and (user "bob" or
Log connections made by users "bob" and "joe" to remote port 25
on machines not on a fictional "intranet".
tcpspy -e ’exe "/usr/bin/irc"’
Log connections made by /usr/bin/irc (probably ircII).
Empty rule files cause tcpspy to log no connections instead of all
Tim J. Robbins <firstname.lastname@example.org>
glob(7), proc(5), services(5), signal(7), syslog(3), syslog.conf(5)