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Machines can have much more complicated routing tables than this one, with lots of different "Destination-Gateway" pairs to connect to different networks. If you have the occasion to connect to an application server, for instance at work, it is most educating to check the routing information.
10.2.6. Other hosts
An impressive amount of tools is focused on network management and remote administration of Linux machines. Your local Linux software mirror will offer plenty of those. It would lead us too far to discuss them in this document, so please refer to the program-specific documentation.
We will only discuss some common UNIX/Linux text tools in this section.
10.2.6.1. The host command
To display information on hosts or domains, use the host command:
[emmy@pc10 emmy]$ host www.eunet.be
www.eunet.be. has address 193.74.208.177
[emmy@pc10 emmy]$ host -t any eunet.be
eunet.be. SOA dns.eunet.be. hostmaster.Belgium.EU.net.
2002021300 28800 7200 604800 86400
eunet.be. mail is handled by 50 pophost.eunet.be. eunet.be. name server ns.EU.net.
eunet.be. name server dns.eunet.be.
[emmy@pc10 emmy]$ host www.eunet.be
www.eunet.be. has address 193.74.208.177
[emmy@pc10 emmy]$ host -t any eunet.be
eunet.be. SOA dns.eunet.be. hostmaster.Belgium.EU.net.
2002021300 28800 7200 604800 86400
eunet.be. mail is handled by 50 pophost.eunet.be. eunet.be. name server ns.EU.net.
eunet.be. name server dns.eunet.be.
Similar information can be displayed using the dig command, which gives additional information about how records are stored in the name server.
10.2.6.2. The ping command
To check if a host is alive, use ping. If your system is configured to send more than one packet, interrupt ping
with the Ctrl+C key combination:
[emmy@pc10 emmy]$ ping a.host.be
PING a.host.be (1.2.8.3) from 80.20.84.26: 56(84) bytes of data.
64 bytes from a.host.be(1.2.8.3):icmp_seq=0 ttl=244 time=99.977msec
--- a.host.be ping statistics ---
1 packets transmitted, 1 packets received, 0% packet loss round-trip min/avg/max/mdev = 99.977/99.977/99.977/0.000 ms
[emmy@pc10 emmy]$ ping a.host.be
PING a.host.be (1.2.8.3) from 80.20.84.26: 56(84) bytes of data.
64 bytes from a.host.be(1.2.8.3):icmp_seq=0 ttl=244 time=99.977msec
--- a.host.be ping statistics ---
1 packets transmitted, 1 packets received, 0% packet loss round-trip min/avg/max/mdev = 99.977/99.977/99.977/0.000 ms
10.2.6.3. The traceroute command
To check the route that packets follow to a network host, use the traceroute command:
[emmy@pc10 emmy]$ /usr/sbin/traceroute www.eunet.be
traceroute to www.eunet.be(193.74.208.177),30 hops max,38b packets 1 blob (10.0.0.1)
0.297ms 0.257ms 0.174ms
2 adsl-65.myprovider.be (217.136.111.1) 12.120ms 13.058ms 13.009ms
3 194.78.255.177 (194.78.255.177)
13.845ms 14.308ms 12.756ms
4 gigabitethernet2-2.intl2.gam.brussels.skynet.be (195.238.2.226) 13.123ms 13.164ms 12.527ms
5 pecbru2.car.belbone.be (194.78.255.118) 16.336ms 13.889ms 13.028ms
6 ser-2-1-110-ias-be-vil-ar01.kpnbelgium.be (194.119.224.9) 14.602ms 15.546ms 15.959ms
7 unknown-195-207-939.eunet.be (195.207.93.49) 16.514ms 17.661ms 18.889ms
8 S0-1-0.Leuven.Belgium.EU.net (195.207.129.1) 22.714ms 19.193ms 18.432ms
9 dukat.Belgium.EU.net (193.74.208.178) 22.758ms * 25.263ms
[emmy@pc10 emmy]$ /usr/sbin/traceroute www.eunet.be
traceroute to www.eunet.be(193.74.208.177),30 hops max,38b packets 1 blob (10.0.0.1)
0.297ms 0.257ms 0.174ms
2 adsl-65.myprovider.be (217.136.111.1) 12.120ms 13.058ms 13.009ms
3 194.78.255.177 (194.78.255.177)
13.845ms 14.308ms 12.756ms
4 gigabitethernet2-2.intl2.gam.brussels.skynet.be (195.238.2.226) 13.123ms 13.164ms 12.527ms
5 pecbru2.car.belbone.be (194.78.255.118) 16.336ms 13.889ms 13.028ms
6 ser-2-1-110-ias-be-vil-ar01.kpnbelgium.be (194.119.224.9) 14.602ms 15.546ms 15.959ms
7 unknown-195-207-939.eunet.be (195.207.93.49) 16.514ms 17.661ms 18.889ms
8 S0-1-0.Leuven.Belgium.EU.net (195.207.129.1) 22.714ms 19.193ms 18.432ms
9 dukat.Belgium.EU.net (193.74.208.178) 22.758ms * 25.263ms
On some systems, traceroute has been renamed to tracepath.
10.2.6.4. The whois command
Specific domain name information can be queried using the whois command, as is explained by many whois
servers, like the one below:
[emmy@pc10 emmy]$ whois cnn.com
[whois.crsnic.net]
Whois Server Version 1.3
$<--snap server message--> Domain Name: CNN.COM
Registrar: NETWORK SOLUTIONS, INC.
Whois Server: whois.networksolutions.com Referral URL: http://www.networksolutions.com Name Server: TWDNS-01.NS.AOL.COM
Name Server: TWDNS-02.NS.AOL.COM Name Server: TWDNS-03.NS.AOL.COM Name Server: TWDNS-04.NS.AOL.COM
Updated Date: 12-mar-2002
>>> Last update of whois database: Fri, 5 Apr 2002 05:04:55 EST <<<
The Registry database contains ONLY .COM, .NET, .ORG, .EDU domains and Registrars.
[whois.networksolutions.com]
$<--snap server message--> Registrant:
Turner Broadcasting (CNN-DOM)
1 CNN Center Atlanta, GA 30303
Domain Name: CNN.COM Administrative Contact:
$<--snap contactinfo--> Technical Contact:
$<--snap contactinfo--> Billing Contact:
$<--snap contactinfo-->
Record last updated on 12-Mar-2002. Record expires on 23-Sep-2009.
Record created on 22-Sep-1993.
Database last updated on 4-Apr-2002 20:10:00 EST.
Domain servers in listed order:
[emmy@pc10 emmy]$ whois cnn.com
[whois.crsnic.net]
Whois Server Version 1.3
$<--snap server message--> Domain Name: CNN.COM
Registrar: NETWORK SOLUTIONS, INC.
Whois Server: whois.networksolutions.com Referral URL: http://www.networksolutions.com Name Server: TWDNS-01.NS.AOL.COM
Name Server: TWDNS-02.NS.AOL.COM Name Server: TWDNS-03.NS.AOL.COM Name Server: TWDNS-04.NS.AOL.COM
Updated Date: 12-mar-2002
>>> Last update of whois database: Fri, 5 Apr 2002 05:04:55 EST <<<
The Registry database contains ONLY .COM, .NET, .ORG, .EDU domains and Registrars.
[whois.networksolutions.com]
$<--snap server message--> Registrant:
Turner Broadcasting (CNN-DOM)
1 CNN Center Atlanta, GA 30303
Domain Name: CNN.COM Administrative Contact:
$<--snap contactinfo--> Technical Contact:
$<--snap contactinfo--> Billing Contact:
$<--snap contactinfo-->
Record last updated on 12-Mar-2002. Record expires on 23-Sep-2009.
Record created on 22-Sep-1993.
Database last updated on 4-Apr-2002 20:10:00 EST.
Domain servers in listed order:
TWDNS-01.NS.AOL.COM TWDNS-02.NS.AOL.COM TWDNS-03.NS.AOL.COM
TWDNS-04.NS.AOL.COM
149.174.213.151
152.163.239.216
205.188.146.88
64.12.147.120
TWDNS-01.NS.AOL.COM TWDNS-02.NS.AOL.COM TWDNS-03.NS.AOL.COM
TWDNS-04.NS.AOL.COM
For other domain names than .com, .net, .org and .edu, you might need to specify the whois server, such as this one for .be domains:
