Netstat: melihat serangan dari netstat
sumber: https://www.cyberciti.biz/tips/netstat-command-tutorial-examples.html
Fitur netstat dan fitur shell pipe bisa digunakan untuk menggali lebih banyak informasi tentang koneksi alamat IP tertentu. Anda dapat menemukan total koneksi yang sudah ada, koneksi penutupan, bit SYN dan FIN dan banyak lagi. Anda juga dapat menampilkan statistik ringkasan untuk setiap protokol menggunakan netstat.
Ini berguna untuk mengetahui apakah server anda diserang atau tidak. Anda juga bisa mencantumkan alamat IP penyerang dengan menggunakan metode ini.
netstat -nat | awk '{print $6}' | sort | uniq -c | sort -n
Output:
1 CLOSE_WAIT
1 established)
1 Foreign
3 FIN_WAIT1
3 LAST_ACK
13 ESTABLISHED
17 LISTEN
154 FIN_WAIT2
327 TIME_WAIT
Menggali informasi lebih lanjut tentang alamat ip tertentu
netstat -nat |grep {IP-address} | awk '{print $6}' | sort | uniq -c | sort -n
2 LAST_ACK
2 LISTEN
4 FIN_WAIT1
14 ESTABLISHED
91 TIME_WAIT
130 FIN_WAIT2
Server yang sibuk dapat memberikan lebih banyak informasi
netstat -nat |grep 202.54.1.10 | awk '{print $6}' | sort | uniq -c | sort -n
Output:
15 CLOSE_WAIT 37 LAST_ACK 64 FIN_WAIT_1 65 FIN_WAIT_2 1251 TIME_WAIT 3597 SYN_SENT 5124 ESTABLISHED
Dapatkan Daftar Semua Alamat IP Unik
Untuk mencetak daftar semua alamat IP yang unik yang terhubung ke server, masukkan:
netstat -nat | awk '{ print $5}' | cut -d: -f1 | sed -e '/^$/d' | uniq
Untuk mencetak total semua alamat IP yang unik, masukkan:
netstat -nat | awk '{ print $5}' | cut -d: -f1 | sed -e '/^$/d' | uniq | wc -l
Contoh Output:
449
Cari tahu jika server kita dalam serangan DoS atau tidak
Jika Anda menganggap kotak Linux Anda diserang, cetaklah daftar koneksi terbuka di server anda dan urutkan menurut alamat IP, masukkan:
netstat -atun | awk '{print $5}' | cut -d: -f1 | sed -e '/^$/d' |sort | uniq -c | sort -n
Output:
1 10.0.77.52
2 10.1.11.3
4 12.109.42.21
6 12.191.136.3
...
...
...
13 202.155.209.202
18 208.67.222.222
28 0.0.0.0
233 127.0.0.1
Anda bisa memblokir semua IP penyerang menggunakan iptables atau hanya membatalkan rute mereka.
Get Live View of TCP Connections
Anda dapat menggunakan perintah tcptrack untuk menampilkan status koneksi TCP yang dilihatnya pada antarmuka jaringan tertentu. Tcptrack memonitor keadaan mereka dan menampilkan informasi seperti alamat negara, sumber / tujuan dan penggunaan bandwidth dalam daftar yang diurutkan dan diperbarui sangat mirip dengan perintah teratas.
Statistik Ringkasan Tampilan untuk Setiap Protokol
Cukup menggunakan netstat -s:
netstat -s | less netstat -t -s | less netstat -u -s | less netstat -w -s | less netstat -s
Output:
Ip:
88354557 total packets received
0 forwarded
0 incoming packets discarded
88104061 incoming packets delivered
96037391 requests sent out
13 outgoing packets dropped
66 fragments dropped after timeout
295 reassemblies required
106 packets reassembled ok
66 packet reassembles failed
34 fragments failed
Icmp:
18108 ICMP messages received
58 input ICMP message failed.
ICMP input histogram:
destination unreachable: 7173
timeout in transit: 472
redirects: 353
echo requests: 10096
28977 ICMP messages sent
0 ICMP messages failed
ICMP output histogram:
destination unreachable: 18881
echo replies: 10096
Tcp:
1202226 active connections openings
2706802 passive connection openings
7394 failed connection attempts
47018 connection resets received
23 connections established
87975383 segments received
95235730 segments send out
681174 segments retransmited
2044 bad segments received.
80805 resets sent
Udp:
92689 packets received
14611 packets to unknown port received.
0 packet receive errors
96755 packets sent
TcpExt:
48452 invalid SYN cookies received
7357 resets received for embryonic SYN_RECV sockets
43 ICMP packets dropped because they were out-of-window
5 ICMP packets dropped because socket was locked
2672073 TCP sockets finished time wait in fast timer
441 time wait sockets recycled by time stamp
368562 delayed acks sent
430 delayed acks further delayed because of locked socket
Quick ack mode was activated 36127 times
32318597 packets directly queued to recvmsg prequeue.
741479256 packets directly received from backlog
1502338990 packets directly received from prequeue
18343750 packets header predicted
10220683 packets header predicted and directly queued to user
17516622 acknowledgments not containing data received
36549771 predicted acknowledgments
102672 times recovered from packet loss due to fast retransmit
Detected reordering 1596 times using reno fast retransmit
Detected reordering 1 times using time stamp
8 congestion windows fully recovered
32 congestion windows partially recovered using Hoe heuristic
19 congestion windows recovered after partial ack
0 TCP data loss events
39951 timeouts after reno fast retransmit
29653 timeouts in loss state
197005 fast retransmits
186937 retransmits in slow start
131433 other TCP timeouts
TCPRenoRecoveryFail: 20217
147 times receiver scheduled too late for direct processing
29010 connections reset due to unexpected data
365 connections reset due to early user close
6979 connections aborted due to timeout
Display Interface Table
You can easily display dropped and total transmitted packets with netstat for eth0:
netstat --interfaces eth0
Output:
Kernel Interface table Iface MTU Met RX-OK RX-ERR RX-DRP RX-OVR TX-OK TX-ERR TX-DRP TX-OVR Flg eth0 1500 0 2040929 0 0 0 3850539 0 0 0 BMRU
Other netstat related articles / tips:
Get Information about All Running Services Remotely Linux / UNIX Find Out What Program / Service is Listening on a Specific TCP Port
Read following man pages for the details:
man netstat man cut man awk man sed man grep
Updated for accuracy.