Ping is a mechanism to see if a remote host is reachable via an IP network
93
votes
14answers
159k views
Ping a Specific Port
Just a quick sanity check here.
Can you ping a specific port of a machine, and if so, can you provide an example?
I'm looking for something like ping ip address portNum.
63
votes
12answers
7k views
Is Ping a reliable way to check if a server is available?
In my application I am pinging a server and waiting for a response. I am using this to determine whether the server is available and responsive or not.
Is this a reliable way of determining ...
24
votes
7answers
170k views
What does “TTL expired in transit” mean on a ping attempt?
We get the message “TTL expired in transit” when we try to ping to a server in a different network segment. When we run tracert, 4 ip addresses repeat themselves indefinitely:
14 60 ms 59 ms ...
22
votes
5answers
42k views
Why do we ping the IP 4.2.2.2 to test connectivity?
For as long as I can remember, I've always used the IP 4.2.2.2 when testing network connectivity using ping. What is significant about this IP, and when did this practice start?
13
votes
6answers
17k views
Enable Ping in Windows Server Firewall?
I've just installed Windows Server 2008 on a server and I'm able to connect through Remote Desktop but can't ping. Do I need to open an special port on the firewall to be able to ping a server?
12
votes
2answers
3k views
Strange: why does linux respond to ping with ARP request after last ping reply?
I (and a colleague) have just noticed, and tested, that when a Linux machine is pinged, after the last ping it initiates a unicast ARP request to the machine that initiated the ICMP ping. When pinging ...
9
votes
11answers
10k views
Will a higher bandwidth Internet connection lower ping response time?
It sounds obvious that a faster connection lowers latency... But I wonder: I am working remotely on a host the other side of the world - light can only travel so fast (1 foot in a nano second) and we ...
9
votes
8answers
35k views
Is there any way to ARP ping on Windows?
On Linux and other systems, there is an utility called arping which can be used to send ARP requests ("pings") and show the answers, much like the "ping" utility but using ARP instead of ICMP.
Is ...
9
votes
3answers
8k views
Why can't I ssh into (or even ping) my Ubuntu VM from the Mac OS X host?
I'm running Ubuntu 8.04 as a virtual machine using VMware Fusion 3.0 on Mac OS X 10.5.8. I want to be able to ssh into my VM from the Mac OS X host (so I can use MacFUSE and SSHFS to mount the VM's ...
8
votes
6answers
3k views
Network latency: 100Mbit vs. 1Gbit
I have a webserver with a current connection of 100Mbit and my provider offers an upgrade to 1Gbit. I understand that this refers to throughput but the larger the packets, the faster they can be ...
7
votes
9answers
3k views
How To Disable Responses To PING
I feel like this should be a really simple thing to do, but googling and checking SF I didn't see anything. I'm trying to make my Fedora server not respond to ping, how do I do that?
7
votes
3answers
757 views
Ping replacement that shows real time
Is there a ping replacement that will display the system's date/time in addition to the round trip time and sequence number? I would prefer a tool that runs on Linux, but if there is a cli tool I can ...
7
votes
2answers
1k views
Public hosts for ping
For my firewall scripts to determine whether my ISP is up I need a few reliable, geographically distributed addresses to ping.
I could just use some major sites like Google, Akamai, etc. But that ...
6
votes
6answers
11k views
How to ping in linux until host is known?
How can I ping a certain address and when found, stop pinging.
I want to use it in a bash script, so when the host is starting up, the script keeps on pinging and from the moment the host is ...
6
votes
1answer
275 views
ping with line numbers
Simple question: how to make ping on Linux to show line numbers in output?
I mean:
1 64 bytes from www.site.com (2.7.1.1): icmp_req=1 ttl=247 time=17.9 ms
2 64 bytes from www.site.com (2.7.1.1): ...
6
votes
8answers
9k views
OS X: Can't Resolve Windows Machine Names
I'm running a mixed environment at home and at work. My server machines are Win Vista, and I have a Unibody Macbook Pro running 10.5.7
On my mac, I can ping some home windows by name (If I use the ...
6
votes
2answers
2k views
DNS can't resolve hostname; nslookup can
I have a user on Windows 7 that is trying to access a local server with a DNS name of windows.cs. We have two internal DNS servers. The DHCP server assigns users the two internal DNS servers as ...
6
votes
4answers
2k views
Linux router: ping doesn't route back
I have a Debian box which I'm trying to set up as a router and an Ubuntu box which I'm using as a client.
My problem is that when the Ubuntu client tries to ping a server on the Internet, all the ...
5
votes
3answers
4k views
What means the mdev column in ping(8)?
What means mdev in the ping output (last row below)?
me@callisto ~ % ping -c 1 example.org
PING example.org (192.0.43.10) 56(84) bytes of data.
64 bytes from 43-10.any.icann.org (192.0.43.10): ...
5
votes
3answers
684 views
Why is ping to Google servers and Google DNS so low?
I noticed that ping to Google DNS and to google.com from Serbia is about 15ms, but google servers are located in California! http://www.geoiptool.com/en/?IP=173.194.39.110 My dedicated server is ...
5
votes
6answers
7k views
How does ping know that my packets are filtered?
I'm customer of an Irish ISP, eircom, which has started censoring the pirate bay.
When I try to ping 194.71.107.15 which is the IP address of thepiratebay.com, I get this output:
PING 194.71.107.15 ...
5
votes
14answers
4k views
How can I determine if a machine is online without using ping?
I used to use an application that could ping or maybe run a port scan on a machine even if the machine was configured to not allow it.
I am currently trying to ping a remote machine on our WAN, but I ...
5
votes
2answers
374 views
Why do I get search.com instead of “host not found”?
On my VPSs with LeaseWeb, whenever I reach an non-existent host, I get search.com domain name, and if I ping a non-existent domain from SSH, I don't get "host not found" but replies from IPs like ...
5
votes
6answers
2k views
Why does traceroute take much longer than ping?
How to explain this?
C:\Documents and Settings\Administrator>tracert google.com
Tracing route to google.com [64.233.189.104]
over a maximum of 30 hops:
1 <1 ms <1 ms <1 ms ...
5
votes
6answers
17k views
Ping “replies” from same computer with 'Destination host unreachable' (no route to other computer)
I've got two computers in a LAN behind a wireless router.
One has XP with ip 192.168.1.2
This one has W7 with ip 192.168.1.7
If I try to ping the other one from this computer, I get this:
...
5
votes
1answer
4k views
IPv6: Can't ping anything - “Operation not permitted”
I've been working on getting IPv6 support into my network, and had everything working properly for a short while. The server is running Ubuntu Server 8.10.
Now however whenever I attempt to do ...
5
votes
2answers
303 views
Why would ping give me fast rtt values, but take a long time for each response to come back?
I've got a bit of a basic networking question here regarding ping.
When pinging a particular host on a completely different subnet, I get a response like this:
PING myhost.example.com (1.2.3.4) ...
5
votes
4answers
4k views
How does TCP Ping or Traceroute Work?
How does the tcp ping or traceroute work? Does it take in account just the time it takes to establis the TCP handshake?
Also in ICMP ping you can specify the packet size, can this be achieved in TCP ...
4
votes
2answers
2k views
Unable to ping, although can download packages
I've installed Debian Squeeze on a Dell PowerEdge server. However, I'm facing some problem with configuring the network. Although I can ping machines inside my network, I'm unable to d0 so outside the ...
4
votes
1answer
530 views
What do the RTT numbers mean in a TraceRoute result?
I have this traceroute result, and I am wondering what EXACTLY do the 3 numbers mean at the end of each line? I assume they are ping times, but what exactly is the difference between each number?
1 ...
4
votes
2answers
1k views
How can I know when my computer is pinged?
I am trying to find a problem on a local network. I want to be able to know when a specific computer (Windows XP) is pinged.
Thanks!
4
votes
1answer
276 views
How can I use ping with a large packet size to troubleshoot network issues?
What types of network problems can be identified with ping of a large packet size?
4
votes
2answers
2k views
Nagios bizare ping behaviour
I have nagios setup as I want it, but last night it started alerting me of a problem pinging the internet. (I have a check that pings www.google.com to test that the internet is still working)
Now ...
4
votes
3answers
2k views
Ping from specific network adapter on Windows
Hey, I've been troubleshooting network issues on servers with 2 NICs and laptops with wired and wireless cards.
How can I force the PING and TELNET to be sent from a specific adapter? I know it's a ...
4
votes
1answer
62 views
tcpdump on interface when pinging nonexistent hosts on local network
I've statically configured the IP address of an interface on a server:
ip addr add 10.40.0.6/16 broadcast 10.40.255.255 dev eth1
If I try to ping a machine on the network (e.g., 10.40.0.1), it ...
4
votes
2answers
517 views
Data obtained from ping: is it round trip or one way?
I have 2 servers, each in two separate locations.
I need to host an application on one, and the database server on the other.
From the app server, if I ping the database server, on average I get ...
4
votes
2answers
4k views
Pings from VPN network to VPN client work; pings into from VPN client to VPN network fail - why?
We are in the process of setting up an OpenVPN server for some servers running in a cloud. We are stumped with a connectivity problem whereby the hosts on the VPN server's LAN can ping te VPN client, ...
4
votes
7answers
188 views
Scan for connected, powered on computers on a network?
I want to scan for powered on computers on my LAN and gather logs about that. I tried nmap but it didn't work very well (a lot of switched on computers are not getting detected).
nmap -sP ...
4
votes
2answers
2k views
nmap does not find alive hosts with ping scan
I try to ping scan my local network using nmap, but it doesn't seem to find machines that are for sure alive. It responses to ping but on to ping scan.
Results for ping:
$ ping 192.168.0.2
PING ...
4
votes
1answer
96 views
negative time for a ping echo reply
I was happily pinging in the net when suddenly:
Pinging X with 32 bytes of data:
Reply from .235: bytes=32 time=1444ms TTL=41
Reply from .235: bytes=32 time=1767ms TTL=41
Reply from .235: bytes=32 ...
4
votes
1answer
2k views
Loop redirect when ping my gateway
I have a router with WAN and LAN setup and act as DHCP server/gateway on my local LAN. The IP address is 192.168.1.1.
Today, I was hit by an internet failure and I checked the ping and get this ...
4
votes
2answers
852 views
openvpn: connection established, can't ping server tun interface (debian server, windows & os x clients)
My goal:
I want to set up openVPN on a vServer from the company netcup, running Debian squeeze. I only want a VPN connection from client to server; clients should not be able to see each other, also ...
3
votes
9answers
3k views
Why am I Unable to ping port 443 on Ubuntu?
I have opened port 443 through iptables:
pkts bytes target prot opt in out source destination
45 2428 ACCEPT all -- lo * 0.0.0.0/0 0.0.0.0/0
6 1009 ACCEPT tcp -- * * 0.0.0.0/0 ...
3
votes
2answers
458 views
How network devices affect TTL
When I do a ping, I can see the TTL value for each packet. For every router that I insert in between my computer and the router that connects to the internet, the TTL value goes down by one. However, ...
3
votes
6answers
8k views
Does a High Variation in Ping Response Times Indicate a Potential Network Issue?
My department has recently moved offices. The previous office was fine, but in the new office, the ping times from my PC to the 2 data centres usually varies a lot, like this:
Reply from ...
3
votes
3answers
156 views
Ping hostname returns another hostname in output : what does it mean?
When I ping the server sip3.voip-centrex.net, I get this output:
PING sip3.voip-centrex.net (194.98.81.144) 56(84) bytes of data.
64 bytes from mpfrrelay.michaelpage.fr (194.98.81.144): icmp_req=1 ...
3
votes
3answers
302 views
Why is DownOrNot and JustPing reporting that my website is down?
I was pinging my site with DownOrNot and it is reporting that my website is down from ALL locations: http://www.downornot.com/qweop
Then I pinged it with JustPing and it is reporting that my website ...
3
votes
3answers
1k views
Find information for local IP address?
We have had a BT engineer visit recently, trying to solve a problem with our IP phone system.
One point they made was that we had four DHCP servers running on the network. I have disabled two of them ...
3
votes
1answer
202 views
How does the ping command differentiate between its ICMP responses and anothers?
If I have two shells open each pinging the same host, how do the two shells differentiate between the ICMP responses coming back for each shell?
3
votes
2answers
732 views
IP address used by nslookup and ping is different
I have a web server hosted in the network. It has a domain name registered. However, I also host a DNS server for the LAN. So, when someone wants to access the web server, it would check the DNS ...
