Red Hat ENTERPRISE LINUX 5.4 - SYSTEMTAP BEGINNERS GUIDE Informations techniques télécharger pdf (Page 97)

SystemTap—Filtering and Analyzing System Data 83

!=: Is not equal to

>=: Is greater than or equal to

<=: Is less than or equal to

5.4 Example Script

If you have installed the systemtap-docs package, you can find a number of

useful SystemTap example scripts in /usr/share/doc/packages/system

tap/examples.

This section describes a rather simple example script in more detail: /

usr/share/doc/packages/systemtap/examples/net

work/tcp_connections.stp.

Example5.5: Monitoring Incoming TCP Connections with tcp_connections.stp

#! /usr/bin/env stap

probe begin {

printf("%6s %16s %6s %6s %16s\n",

"UID", "CMD", "PID", "PORT", "IP_SOURCE")

}

probe kernel.function("tcp_accept").return?,

kernel.function("inet_csk_accept").return? {

sock = $return

if (sock != 0)

printf("%6d %16s %6d %6d %16s\n", uid(), execname(), pid(),

inet_get_local_port(sock), inet_get_ip_source(sock))

}

This SystemTap script monitors the incoming TCP connections and helps to identify

unauthorized or unwanted network access requests in real time. It shows the following

information for each new incoming TCP connection accepted by the computer:

• User ID (UID)

• Command accepting the connection (CMD)

• Process ID of the command (PID)

• Port used by the connection (PORT)

1 2 ... 92 93 94 95 96 97 98 99 100 101 102 ... 239 240

Pas de commentaire

Red Hat ENTERPRISE LINUX 5.4 - SYSTEMTAP BEGINNERS GUIDE Informations techniques Page 97