Based on the netstat output shown in item (d), what is the Layer 4 protocol, connection status, and PID of the process running on port 80?
Display the services currently running.
a. Use the ps command to display all the programs running in the background:
[analyst@secOps ~]$ sudo ps –elf
[sudo] password for analyst:
F S UID PID PPID C PRI NI ADDR SZ WCHAN STIME TTY TIME CMD
4 S root 1 0 0 80 0 - 2250 SyS_ep Feb27 ? 00:00:00 /sbin/init
1 S root 2 0 0 80 0 - 0 kthrea Feb27 ? 00:00:00 [kthreadd]
1 S root 3 2 0 80 0 - 0 smpboo Feb27 ? 00:00:00 [ksoftirqd/0]
1 S root 5 2 0 60 -20 - 0 worker Feb27 ? 00:00:00 [kworker/0:0H]
1 S root 7 2 0 80 0 - 0 rcu_gp Feb27 ? 00:00:00 [rcu_preempt]
1 S root 8 2 0 80 0 - 0 rcu_gp Feb27 ? 00:00:00 [rcu_sched]
1 S root 9 2 0 80 0 - 0 rcu_gp Feb27 ? 00:00:00 [rcu_bh]
1 S root 10 2 0 -40 - - 0 smpboo Feb27 ? 00:00:00 [migration/0]
1 S root 11 2 0 60 -20 - 0 rescue Feb27 ? 00:00:00 [lru-add-drain]
5 S root 12 2 0 -40 - - 0 smpboo Feb27 ? 00:00:00 [watchdog/0]
1 S root 13 2 0 80 0 - 0 smpboo Feb27 ? 00:00:00 [cpuhp/0]
5 S root 14 2 0 80 0 - 0 devtmp Feb27 ? 00:00:00 [kdevtmpfs]
1 S root 15 2 0 60 -20 - 0 rescue Feb27 ? 00:00:00 [netns]
1 S root 16 2 0 80 0 - 0 watchd Feb27 ? 00:00:00 [khungtaskd]
1 S root 17 2 0 80 0 - 0 oom_re Feb27 ? 00:00:00 [oom_reaper]
b. In Linux, programs can also call other programs. The ps command can also be used to display such process hierarchy. Use –ejH options to display the currently running process tree.
[analyst@secOps ~]$ sudo ps –ejH
[sudo] password for analyst:
1 1 1 ? 00:00:00 systemd
167 167 167 ? 00:00:01 systemd-journal
193 193 193 ? 00:00:00 systemd-udevd
209 209 209 ? 00:00:00 rsyslogd
210 210 210 ? 00:01:41 java
212 212 212 ? 00:00:01 ovsdb-server
213 213 213 ? 00:00:00 start_pox.sh
224 213 213 ? 00:01:18 python2.7
214 214 214 ? 00:00:00 systemd-logind
216 216 216 ? 00:00:01 dbus-daemon
221 221 221 ? 00:00:05 filebeat
239 239 239 ? 00:00:05 VBoxService
287 287 287 ? 00:00:00 ovs-vswitchd
382 382 382 ? 00:00:00 dhcpcd
387 387 387 ? 00:00:00 lightdm
410 410 410 tty7 00:00:10 Xorg
460 387 387 ? 00:00:00 lightdm
492 492 492 ? 00:00:00 sh
503 492 492 ? 00:00:00 xfce4-session
513 492 492 ? 00:00:00 xfwm4
517 492 492 ? 00:00:00 Thunar
1592 492 492 ? 00:00:00 thunar-volman
519 492 492 ? 00:00:00 xfce4-panel
554 492 492 ? 00:00:00 panel-6-systray
559 492 492 ? 00:00:00 panel-2-actions
523 492 492 ? 00:00:01 xfdesktop
530 492 492 ? 00:00:00 polkit-gnome-au
395 395 395 ? 00:00:00 nginx
396 395 395 ? 00:00:00 nginx
408 384 384 ? 00:01:58 java
414 414 414 ? 00:00:00 accounts-daemon
418 418 418 ? 00:00:00 polkitd
c. As mentioned before, servers are essentially programs, often started by the system itself at boot time. The task performed by a server is called service. In such fashion, a web server provides web services.
The netstat command is a great tool to help identify the network servers running on a computer. The power of netstat lies on its ability to display network connections.
In the terminal window, type netstat.
[analyst@secOps ~]$ netstat
Active Internet connections (w/o servers)
Proto Recv-Q Send-Q Local Address Foreign Address State
tcp 0 0 localhost.localdo:48746 localhost.local:wap-wsp ESTABLISHED
tcp 0 0 localhost.localdo:48748 localhost.local:wap-wsp ESTABLISHED
tcp6 0 0 localhost.local:wap-wsp localhost.localdo:48748 ESTABLISHED
tcp6 0 0 localhost.local:wap-wsp localhost.localdo:48746 ESTABLISHED
tcp6 0 0 localhost.local:wap-wsp localhost.localdo:48744 ESTABLISHED
tcp6 0 0 localhost.localdo:48744 localhost.local:wap-wsp ESTABLISHED
Active UNIX domain sockets (w/o servers)
Proto RefCnt Flags Type State I-Node Path
unix 3 [ ] DGRAM 8472 /run/systemd/notify
unix 2 [ ] DGRAM 8474 /run/systemd/
cgroups-agent
d. Use netstat with the –tunap options to adjust the output of netstat. Notice that netstat allows multiple options to be grouped together under the same “- ” sign.
The information for the nginx server is highlighted.
[analyst@secOps ~]$ sudo netstat -tunap
[sudo] password for analyst:
Active Internet connections (servers and established)
Proto Recv-Q Send-Q Local Address Foreign Address State
PID/Program name
tcp 0 0 0.0.0.0:80 0.0.0.0:* LISTEN
395/nginx: master p
tcp 0 0 0.0.0.0:21 0.0.0.0:* LISTEN
279/vsftpd
tcp 0 0 0.0.0.0:22 0.0.0.0:* LISTEN
277/sshd
tcp 0 0 0.0.0.0:6633 0.0.0.0:* LISTEN
257/python2.7
tcp6 0 0 :::22 :::* LISTEN
277/sshd
tcp6 0 0 :::23 :::* LISTEN
1/init
udp 0 0 192.168.1.15:68 0.0.0.0:*
237/systemd-network
Clients will connect to a port and, using the correct protocol, request information from a server. The netstat output above displays a number of services that are currently listening on specific ports. Interesting columns are:
? The first column shows the Layer 4 protocol in use (UDP or TCP, in this case).
? The third column uses the
? The fourth column uses the same socket format
? The fifth column displays the state of the connection.
? The sixth column displays the process ID (PID) of the process responsible for the connection. It also displays a short name associated to the process.
TCP, LISTEN and 395.
Computer Science & Information Technology
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