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Internet Tool Practice

Internet Tool Practice. 한두균 ( dkhan@mmlab.snu.ac.kr ) 송정환 ( jhsong @mmlab.snu.ac.kr ) 2012. 4. 30. Outline. Internet Tools ping traceroute nslookup ifconfig arp netstat synack nmap Iperf crontab Homeworks. ping (1/3). Send an ICMP ECHO_REQUEST message to a host

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Internet Tool Practice

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  1. Internet Tool Practice 한두균 (dkhan@mmlab.snu.ac.kr) 송정환 (jhsong@mmlab.snu.ac.kr) 2012. 4. 30

  2. Outline • Internet Tools • ping • traceroute • nslookup • ifconfig • arp • netstat • synack • nmap • Iperf • crontab • Homeworks

  3. ping (1/3) • Send an ICMP ECHO_REQUEST message to a host • Test whether another host is reachable • Measures the Round-Trip Time(RTT) to the host • Usage • ping [-options value ] destination • Option type : -s (size), -c (count), -i (interval ), -t (TTL) etc. • Ex) ping –c 5 mmlab.snu.ac.kr • Reference • In the UNIX-like system, man ping • Because the options of ping are different according to OS, see man-page for details • Applicable to all the commands introduced here

  4. ping (2/3) $ ping -c 3 -t 10 mmlab.snu.ac.kr PING mmlab.snu.ac.kr (147.46.114.112) 56(84) bytes of data. 64 bytes from mmlab.snu.ac.kr (147.46.114.112): icmp_seq=1 ttl=62 time=1.57 ms 64 bytes from mmlab.snu.ac.kr (147.46.114.112): icmp_seq=2 ttl=62 time=0.387 ms 64 bytes from mmlab.snu.ac.kr (147.46.114.112): icmp_seq=3 ttl=62 time=1.41 ms --- mmlab.snu.ac.kr ping statistics --- 3 packets transmitted, 3 received, 0% packet loss, time 2005ms rtt min/avg/max/mdev = 0.387/1.125/1.574/0.525 ms

  5. ping (3/3) $ ping -c 3 -i 3 mmlab.snu.ac.kr PING mmlab.snu.ac.kr (147.46.114.112) 56(84) bytes of data. 64 bytes from mmlab.snu.ac.kr (147.46.114.112): icmp_seq=1 ttl=62 time=0.411 ms 64 bytes from mmlab.snu.ac.kr (147.46.114.112): icmp_seq=2 ttl=62 time=0.550 ms 64 bytes from mmlab.snu.ac.kr (147.46.114.112): icmp_seq=3 ttl=62 time=80.0 ms --- mmlab.snu.ac.kr ping statistics --- 3 packets transmitted, 3 received, 0% packet loss, time 6005ms rtt min/avg/max/mdev = 0.411/27.002/80.045/37.507 ms

  6. traceroute (1/2) • Let us see the route that IP datagrams follow from one host to another • Although there are no guarantees that two consecutive IP datagrams from the same source to the same destination follow the same route, most of the time they do. • Usage • traceroute [-options value ] hostname • Ex) traceroute www.snu.ac.kr

  7. traceroute (2/2) $ traceroute mmlab.snu.ac.kr traceroute to mmlab.snu.ac.kr (147.46.114.112), 30 hops max, 40 byte packets 1 147.46.240.1 (147.46.240.1) 0.411 ms 0.429 ms 1.357 ms 2 147.47.20.129 (147.47.20.129) 13.857 ms 0.463 ms 1.358 ms 3 mmlab (147.46.114.112) 0.330 ms 0.546 ms 1.359 ms $ traceroute www.cs.berkeley.edu traceroute to hyperion.cs.berkeley.edu (169.229.60.105), 30 hops max, 38 byte packets 1 147.46.113.2 (147.46.113.2) 0.353 ms 0.281 ms 0.275 ms 2 147.46.200.25 (147.46.200.25) 0.264 ms 0.224 ms 0.222 ms 3 147.46.254.129 (147.46.254.129) 0.871 ms 1.017 ms 1.273 ms 4 147.46.254.26 (147.46.254.26) 1.641 ms 2.049 ms 1.854 ms 5 202.30.43.33 (202.30.43.33) 2.186 ms 1.664 ms 1.870 ms 6 seoulgsr.kreonet.net (134.75.12.6) 1.912 ms 1.925 ms 1.890 ms 7 baramgsr-seoulgsr.kreonet.net (134.75.1.1) 5.097 ms 6.110 ms 5.012 ms ……. 17 hyperion.CS.Berkeley.EDU (169.229.60.105) 217.609 ms 217.629 ms 218.099 ms

  8. nslookup (1/2) • Allow anyone to directly query a name server and retrieve any of the information known to the DNS System • Usage • nslookup [ - option ] [ name | - ] [ server ] • interactive mode • non-interactive mode • Otherprograms • host google.co.kr • dig google.co.kr

  9. nslookup (2/2) $ nslookup > mmlab.snu.ac.kr Server: 147.46.80.1 Address: 147.46.80.1#53 Name: mmlab.snu.ac.kr Address: 147.46.114.112 > 147.46.114.112 Server: 147.46.80.1 Address: 147.46.80.1#53 112.114.46.147.in-addr.arpa name = mmlab.snu.ac.kr. $ nslookup cse.snu.ac.kr Server: 147.46.80.1 Address: 147.46.80.1#53 Non-authoritative answer: Name: cse.snu.ac.kr Address: 147.46.240.39

  10. ifconfig • Check the network interface configuration • Usage • ifconfig [interface] $ /sbin/ifconfig eth0 Link encap:Ethernet HWaddr 00:B0:D0:68:B1:C6 inet addr:147.46.240.47 Bcast:147.46.240.255 Mask:255.255.255.0 inet6 addr: fe80::2b0:d0ff:fe68:b1c6/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:69962395 errors:0 dropped:0 overruns:150 frame:150 TX packets:35559225 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:3286312879 (3.0 GiB) TX bytes:48791130 (46.5 MiB) ……..

  11. arp • Manipulate the system ARP cache • Usage • arp [option] hostname $ arp -a ? (147.46.114.1) at 00:00:0c:07:ac:00 on rl0 [ethernet] ? (147.46.114.2) at 00:d0:02:cb:e3:fc on rl0 [ethernet] ? (147.46.114.10) at 00:0a:5e:01:e2:ba on rl0 [ethernet] ? (147.46.114.33) at 00:e0:98:b0:fa:7d on rl0 [ethernet] ? (147.46.114.93) at 00:04:76:d0:0a:ab on rl0 [ethernet] csebrg1.snu.ac.kr (147.46.114.102) at 00:50:04:bf:c5:b9 on rl0 [ethernet] topaz.snu.ac.kr (147.46.114.113) at 00:0d:61:3b:8f:59 on rl0 [ethernet] garnet.snu.ac.kr (147.46.114.114) at 00:0e:35:0d:fe:96 on rl0 [ethernet] opal.snu.ac.kr (147.46.114.116) at 00:11:11:0f:2f:c0 on rl0 [ethernet] emerald.snu.ac.kr (147.46.114.118) at 00:4f:4e:0d:51:2d on rl0 [ethernet] smart1.snu.ac.kr (147.46.114.120) at 00:00:f0:91:0d:3a on rl0 [ethernet] ? (147.46.114.193) at 00:50:da:91:0b:0d on rl0 [ethernet] …

  12. netstat (1/2) • Show network status • Usage • netstat [option] • Options • -a : show the state of all sockets. But normally sockets used by server processes are not shown. • -i : show status and statistics for the physical interfaces • -n : show network addresses as numbers • -r : show the routing table

  13. netstat (2/2) $ netstat –r Kernel IP routing table Destination Gateway Genmask Flags MSS Window irtt Iface localnet * 255.255.255.0 U 0 0 0 eth0 default 147.46.240.1 0.0.0.0 UG 0 0 0 eth0 $ netstat –rn Kernel IP routing table Destination Gateway Genmask Flags MSS Window irtt Iface 147.46.240.0 0.0.0.0 255.255.255.0 U 0 0 0 eth0 0.0.0.0 147.46.240.1 0.0.0.0 UG 0 0 0 eth0

  14. synack (1/3) • Description • Establishes a Client-Server connection by calling connect which performs the 3-way Handshake of the TCP Protocol • Measures the time taken for the connection to be established b/w the client & server • Closes the connection once the RTT is measured by calling close which performs a 4-packet exchange • Repeats the above process at regular intervals (defined by the user) after the connection is closed • Performs statistical analysis on the RTT data obtained • Reference • http://www-iepm.slac.stanford.edu/tools/synack/

  15. synack (2/3) • Usage • synack [-options] host • Options • -p ## port number to send to (default 22) • -k ## no. of connections to be made • -i ## Time interval between connections in secs (default 1 sec) • -u ## Time interval between connections in microsecs • -z ## Percentile 1 (default 25) • -Z ## Percentile 2 (default 75) • -S ## Timout in secs (default 1 Sec) • -s ## Timeout in millisecs

  16. synack (3/3) $ ./synack -p 80 -k 10 www.snu.ac.kr SYN-ACK to moose.snu.ac.kr (147.46.10.48), 10 Packets connected to moose.snu.ac.kr : Seq = 0 , RTT = 0.685 ms connected to moose.snu.ac.kr : Seq = 1 , RTT = 0.612 ms connected to moose.snu.ac.kr : Seq = 2 , RTT = 1.754 ms connected to moose.snu.ac.kr : Seq = 3 , RTT = 0.718 ms connected to moose.snu.ac.kr : Seq = 4 , RTT = 0.711 ms connected to moose.snu.ac.kr : Seq = 5 , RTT = 0.667 ms connected to moose.snu.ac.kr : Seq = 6 , RTT = 1.775 ms connected to moose.snu.ac.kr : Seq = 7 , RTT = 0.673 ms connected to moose.snu.ac.kr : Seq = 8 , RTT = 1.782 ms connected to moose.snu.ac.kr : Seq = 9 , RTT = 0.638 ms Waiting for outstanding packets (if any).......... ***** Round Trip Statistics of SYN-ACK to moose.snu.ac.kr (Port = 80) ****** 10 packets transmitted, 10 packets received, 0.00 percent packet loss round-trip (ms) min/avg/max = 0.612/1.001/1.782 (std = 0.531) (median = 0.698) (interquartile range = 1.087) (25 percentile = 0.667) (75 percentile = 1.754)

  17. nmap (1/2) • Network Mapper • Network exploration tool and security scanner • Scan large networks to determine which hosts are up and what services are offering • Usage • nmap [Scan Types] [ Options] <host> • Reference • http://nmap.org • In the unix shell, man nmap

  18. nmap (2/2) $ nmap mmlab.snu.ac.kr Starting Nmap 4.11 ( http://www.insecure.org/nmap/ ) at 2008-03-18 16:39 KST Interesting ports on mmlab.snu.ac.kr (147.46.114.112): Not shown: 1504 closed ports, 170 filtered ports PORT STATE SERVICE 22/tcp open ssh 25/tcp open smtp 80/tcp open http 110/tcp open pop3 587/tcp open submission 3306/tcp open mysql Nmap finished: 1 IP address (1 host up) scanned in 9.968 seconds

  19. iperf (1/2) • A tool to measure maximum TCP bandwidth • allowing the tuning of various parameters and UDP characteristics • Reports bandwidth, delay jitter, datagram loss • for a TCP connection : throughput, bandwidth • for a UDP connection : throughput, jitter, lost/total datagram • Usage • iperf [-s|-c host] [options]

  20. iperf (2/2) $ iperf -s ------------------------------------------------------------ Server listening on TCP port 5001 TCP window size: 85.3 KByte (default) ------------------------------------------------------------ [ 4] local 147.46.240.47 port 5001 connected with 147.46.240.47 port 34169 [ 4] 0.0-10.0 sec 1.25 GBytes 1.07 Gbits/sec $ iperf –c martini.snu.ac.kr ------------------------------------------------------------ Client connecting to martini.snu.ac.kr, TCP port 5001 TCP window size: 49.4 KByte (default) ------------------------------------------------------------ [ 3] local 147.46.240.47 port 34169 connected with 147.46.240.47 port 5001 [ 3] 0.0-10.0 sec 1.25 GBytes 1.08 Gbits/sec

  21. Crontab • crontab [ -u user ] { -l | -r | -e } • -u user user 사용자에 대해서 crontab 작업을 수행한다. 생략하면 crontab 명령을 실행하는 사용자에 대해서 crtontab 작업을 수행. • -l 현재 cron table을 보여 준다. • -r 현재 cron table을 삭제한다. • -e 현재 cron table을 편집한다. • cron table의 각 필드 • minute(0~59) hour(0-23) day(1-31) month(1-12) weekday(1-7) command • 요일 필드 : 1(월), 2(화), 3(수), 4(목), 5(금), 6(토), 7(일) • '*' : everytime • '-' : 범위 지정, 예를 들어 시간 필드에 1-3이면 1시와 3시 사이 즉 1시 2시 3시 • ',' : separator, 예를 들어 시간 필드에 1,3이면 1시와 3시 • 사용 예 • 30 14 * * 1 ~/bin/log_cat • 매주 월요일 오후 2시 30분에 ~/bin/log_cat을 실행 • 30 2 1 * * ~/bin/log_report • 매월 1일 새벽 2시 30분에 ~/bin/log_report를 실행

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