Wie verwende ich ICMP, um die Erreichbarkeit einer Site zu überprüfen?

817
psaw.mora

Wenn ich sicher wissen möchte, dass eine Website wirklich von den Behörden blockiert wird oder die Website selbst vorgetäuscht hat, welche Methode kann ich verwenden? Ich meine, wenn wir traceres benutzen, benutzen Sie einfach den ICMP ... Aber ist es möglich, dass eine Website auch nach einer erfolgreichen Verfolgung blockiert wird? (wie das Blockieren von TCP-Ports)

0
Die DNS-Blockierung würde Sie lediglich daran hindern, die IP des Servers von seinem Domänennamen aufzulösen. (Update: Der Kommentar, auf den ich referenziert habe, wurde entfernt, na ja ...) Polynomial vor 12 Jahren 0

3 Antworten auf die Frage

2
Polynomial

You can't use ICMP alone to discover if a service is up. It's just another protocol that the machine happens to accept and have appropriate daemons for. A ping will show you that the machine is up and accepting ICMP ECHO requests, but it can't tell you that a service is listening on a TCP port. Since some servers don't respond to ICMP requests or have firewalls that block those requests, ICMP won't always be reliable.

In order to test if a specific service is up, just attempt a TCP connection to that service.

In order to test if your route to the host is being blocked, use a VPN and attempt to access the site from a different country. You could also use a down/up test like http://downforeveryoneorjustme.com/ to test if the HTTP daemon is up and available from somewhere else.

0
Ray

Quickest way to see if the server for the website is up is to ping the web address, if it returns an ip address, but all the echo replies time out, that is a good indication that the server is up. This trick works in all operating systems.

Example (from a Unix/Linux system):

user$:ping amazon.ca PING amazon.ca (72.21.206.110): 56 data bytes Request timeout for icmp_seq 0 Request timeout for icmp_seq 1

Another option if you run a linux system is to use a tool called zenmap, which is built off of nmap. It is a port scanner, so if it reports that port 80 is active then you know the web server is up. It is not illegal to use a port scanner, just be careful as some ISPs have in their service agreement that their customers cannot use tools like port scanners.

0
Maxim Egorushkin

You may like to use hping which determines whether a TCP service is up by sending TCP SYN request and waiting for SYN/ACK response. It works more reliably than ICMP ping because, as they said, the host may be blocking ICMP responses.

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