Ping

ping (packed internet grouper) ist ein Programm / Befehl zum Prüfen der Erreichbarkeit von anderen Rechnern oder Geräten über ein (beliebiges) Netzwerk.

Installation

Die Programme ping und ping6 sind in jeder Installation bereits enthalten und im Paket iputils-ping integriert.

Syntax

Der Befehl hat die folgende, allgemeine Syntax:

$ ping OPTIONEN IP-ADRESSE

Anstelle der IP-Adresse kann auch ein Host-Name angegeben werden. Es wird dann versucht, diesen in eine DNS-Adresse aufzulösen.

$ ping OPTIONEN 10.10.0.1

Man muss ping entweder händisch stoppen (mit Strg + C ) oder mit der entsprechenden Option die Anzahl der gesendeten Pakete begrenzen.

Es gibt zwei Varianten des ping-Befehl

• ping - für IPv4-Adressen
• ping6 - für IPv6-Adressen

$ ping www.google.com       >>  zeigt uns ip von google    
64 bytes from ams15s33-in-f4.1e100.net (172.217.20.68): icmp_seq=1 ttl=119 time=15.8 m

Optionen

-4 Use IPv4 only.

-6 Use IPv6 only.

-a Audible ping.

-A Adaptive ping. Interpacket interval adapts to round-trip time, so that effectively not more than one (or more, if preload is set) unanswered probe is present in the network. Minimal interval is 200msec unless super-user. On networks with low RTT this mode is essentially equivalent to flood mode.

-b Allow pinging a broadcast address.

-B Do not allow ping to change source address of probes. The address is bound to one selected when ping starts.

-c count Stop after sending count ECHO_REQUEST packets. With deadline option, ping waits for count ECHO_REPLY packets, until the timeout expires.

-d Set the SO_DEBUG option on the socket being used. Essentially, this socket option is not used by Linux kernel.

-D Print timestamp (unix time + microseconds as in gettimeofday) before each line.

-f Flood ping. For every ECHO_REQUEST sent a period “.” is printed, while for every ECHO_REPLY received a backspace is printed. This provides a rapid display of how many packets are being dropped. If interval is not given, it sets interval to zero and outputs packets as fast as they come back or one hundred times per second, whichever is more. Only the super-user may use this option with zero interval.

-F flow label IPv6 only. Allocate and set 20 bit flow label (in hex) on echo request packets. If value is zero, kernel allocates random flow label.

-h Show help.

-i interval Wait interval seconds between sending each packet. Real number allowed with dot as a decimal separator (regardless locale setup). The default is to wait for one second between each packet normally, or not to wait in flood mode. Only super-user may set interval to values less than 0.2 seconds.

-I interface interface is either an address, an interface name or a VRF name. If interface is an address, it sets source address to specified interface address. If interface is an interface name, it sets source interface to specified interface. If interface is a VRF name, each packet is routed using the corresponding routing table; in this case, the -I option can be repeated to specify a source address. NOTE: For IPv6, when doing ping to a link-local scope address, link specification (by the '%'-notation in destination, or by this option) can be used but it is no longer required.

-l preload If preload is specified, ping sends that many packets not waiting for reply. Only the super-user may select preload more than 3.

-L Suppress loopback of multicast packets. This flag only applies if the ping destination is a multicast address.

-m mark use mark to tag the packets going out. This is useful for variety of reasons within the kernel such as using policy routing to select specific outbound processing.

-M pmtudisc_opt Select Path MTU Discovery strategy. pmtudisc_option may be either do (prohibit fragmentation, even local one), want (do PMTU discovery, fragment locally when packet size is large), or dont (do not set DF flag).

-N nodeinfo_option IPv6 only. Send ICMPv6 Node Information Queries (RFC4620), instead of Echo Request. CAP_NET_RAW capability is required.

Anwendungen

Option	Beispiele
-c ANZAHL	$ ping -c 10 itw-berlin.net
-w ENDE	$ ping -w 15 itw-berlin.net
-W AUSZEIT	$ ping -W 015 itw-berlin.net
-i INTERVALL	$ ping -i 15 itw-berlin.net
-I SCHNITTSTELLE	$ ping -I enp2s0 ($ ip a)itw-berlin.net

Ping und MTU

• Die im Befehl ping angegebene Größe entspricht der Anzahl der zu sendenden Datenbytes.
• Diese muss also 28 Byte kleiner sein als die tatsächliche Paketgröße, um die Größe des Paket-Headers zu berücksichtigen.
• Dieser lässt sich recht einfach über Bordmittel des Betriebssystems bestimmen.

Beispiel

$ ping -s 1500 -c 10 -M do <Hostname>

Links

Weblinks

• https://wiki.ubuntuusers.de/ping/
• https://www.tecchannel.de/a/tcp-ip-tuning-fuer-linux,429773,2

Testfragen

Testfrage 1

Antwort1

Testfrage 2

Antwort2

Testfrage 3

Antwort3

Testfrage 4

Antwort4

Testfrage 5

Antwort5