Ubuntu Networking :: Nmap Ping A Pc With Icmp Disabled?

Nov 13, 2010

I tried to ping some of the pcs on the local network but for those with icmp disabled it doesn't work. I've used

nmap -sP

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Ubuntu Networking :: Ping ICMP Warning - Duplicates Packets

Sep 28, 2010

When I ping our Microsoft Windows terminal server "cluster" farm, I get ICMP warnings that there are duplicate packets. I am able to rdesktop to the cluster with no problems. We are trying to setup nagios to run on this Ubuntu configuration and nagios is reporting the following error:
"PING WARNING - DUPLICATES! Packet Loss=0%, RTA=.98ms.
FPing reports duplicates as well. Is there a setting in the Arp table that needs to be set differently because the "Cluster" MAC address isn't an actual hardware MAC but a virtual MAC address?

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CentOS 5 Networking :: ICMP Ping Latency Grows Over Time

Apr 20, 2011

I have a dedicated host on my lan to monitor other hosts/services using Nagios. I'm in the process of migrating to Zabbix on that host to perform the same purpose. Both Nagios and Zabbix monitor icmp ping latency (Nagios uses ping, Zabbix uses fping) and over time the latency to other hosts grows until threshold alarms are triggered. In one week, the average latency grows from sub-millisecond to over 100 milliseconds, and continues to grow until the Nagios host is rebooted. I have verified the latency numbers using ping/fping from the command line on the Nagios host.

The problem is that pings from the monitored hosts to the Nagios host show normal latency at the time the Nagios host is showing high latency from itself to the monitored hosts. The Nagios host and monitored hosts are all connected to the same Dell 24 port gigabit switch. I already posted this question on the Zabbix forums with a graph of the latency but there were no answers. [URL] why the icmp ping latency is growing over time and how I can fix it short of rebooting the host on a schedule.


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Networking :: How To Disabled Ping In Network

Aug 27, 2010

Is there a way to disable ping in the network instead ping of IP addresses must be hostname or a name.

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Security :: How To Enable ICMP Ping For One Host Only

Dec 9, 2010

I need to allow ICMP ping for one host only. I found out how to enable it to all hosts (ICMP Filtering, check ping) but I would like to reduce the scope to one host. I know I can add rules in the user_post script but I can't find the correct iptables command ...

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SUSE / Novell :: Write IPTABLES Script To Block The ICMP Ping?

Mar 13, 2010

I was trying to write IPTABLES script to block the ICMP ping using the below mentioned command in OpenSUSE 11.2 Doing this in VMware.....

iptables -A OUTPUT -o eth0 -p icmp -j DROP

& then I tried to ping the different computer & it didnt allow me to ping.
Then I deleted using the command -

iptables -D OUTPUT -o eth0 -p icmp -j DROP

then I couldnt ping also. Another thing I found is my firefox is not connecting to the internet as well, but before writing the script, I can connect to internet.

I did a "dhclient" & iptables -F....

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Networking :: Cannot Ping With Command - Ping IP - Address But Can Ping With - Ping IP -I Eth0

Jul 15, 2011

I am using an virtual machine. where I need to ping from one machine to another. earlier I was able to ping. But after going to google.com once, I cannot ping back to this machine.

But if I gave ping -I eth1 <IP> then I can ping.

I cannot install any package, so tell me solution which includes not installing any package.

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Ubuntu Security :: UFW Block ICMP When Add Non ICMP Related Rule

May 21, 2011

I am setting up a virtual server. Ubuntu 11.04, "minimal provider image".UFW was disabled by default. I set it to default deny. Allowed HTTP, SSH and other standard stuff, and enabled it. All seems to be OK. Adding one rule to block some annoying security scanners causes ping not to work. I'm not an Iptables expert, but it looks OK to me. I got it from some website, rather than invented it myself, but modified to to fit the ufw config file syntax. What in that rule prevents pings?!? It seems completely unrelated.

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Server :: Error: No Route To Host" Both Systems Ping Each Other And Firewall Is Also Disabled

Feb 2, 2010

using redhat on server machine and open suse on client machine.i have installed nfs server and and it is running properly but when i want to mount shares from my client machine it gives the following.

error. "mount.nfs: mount to NFS server '' failed: System Error: No route to host" both systems ping each other and firewall is also disabled. another problem is when i remotely access from my server machine to client machine it gives the following error ssh:connect to host port 22:connection refused what can be the problem?

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Ubuntu Networking :: Unable To Ping Over Wireless But Can Ping Over Wired?

Jul 24, 2010

I have two machines on this network, one running Ubuntu and the other running Fedora.

When I'm using the Wireless network on the Ubuntu machine, I cannot ping the Fedora machine. Everything else works. I can browse the net fine.

If I switch over to the Wired Network then I can ping the other machine.

I don't understand why ping doesn't work only over the Wireless. I can ping the router so I'm guessing it's getting blocked by the router but I didn't block ICMP traffic.

I tried asking on IRC and they ran out of ideas too to find out where the problem is.

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Networking :: Using NMAP On A Range Of IP Addresses

Dec 21, 2010

Hopefully Ody has found a result in the 5 years since he posted this question, for anyone else looking for an answer
NMAP scan for a range of individual IP's can be done using the '-' for example:
(this is accurate as of 2010, actual results have been altered to match OP's address range)

$nmap -sP

Starting Nmap 5.00 ( http://nmap.org ) at 2010-12-22 09:55
Interesting ports on
Not shown: 999 closed ports
80/tcp open http

Interesting ports on
Not shown: 999 closed ports
80/tcp open http

Interesting ports on
Not shown: 999 closed ports
80/tcp open http

Nmap done: 14 IP addresses (3 hosts up) scanned in 8.08 seconds

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Networking :: Debian 5 - After SysCp Installation And Configure Ping Valure - Ping - Unknown Host

Jul 9, 2010

Ive got a problem on my server ....installed Debian 5 , Webmin and than syscp settung up syscp ready ....

I try to ping "localhost" ansver ping: unknown host
I try to ping "localhost." there is a host with IP

I need it to change it in "localhost"

Is that the bind9 maybe?

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Networking :: Can Nmap Detect Port-sharing

Sep 28, 2010

Since I no longer have access to a spare machine to actually test this out on, I was hoping some kind soul might know the answer, or be willing to try it out for me. I'm trying to find out if the port scanner nmap can detect two different services which are sharing a single port. For instance, if I'd managed to set up, I dunno, a web server and an ftp server to both run over the same port, would nmap with version detection be able to detect both of them, or just one?

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Networking :: Nmap Showing Wrong Information?

Oct 16, 2010

I'm not too sure if this is the right topic to post in but if it isn't please move it to the correct topic. I recently opened some ports for my Playstation 3 and the connection test on the PS3 tells me that the ports are open . But when I execute this command

nmap -p 0-60000 I get this


Starting Nmap 5.21 ( http://nmap.org ) at 2010-10-16 20:54 AUS Eastern Daylight
Time Nmap scan report for PS3 (
Host is up (0.00063s latency).
All 60001 scanned ports on PS3 ( are closed
MAC Address: **:**:**:**:**:** (Sony Computer Entertainment)

Nmap done: 1 IP address (1 host up) scanned in 4.12 seconds

I could be executing the wrong command or something but I have read through the manual and couldn't find anything that helped. I have tried this command on other machines that I have opened ports for and get similar results except for a few Ephemeral ports (80,443 etc.) which also makes me wonder why these aren't listed as open on the PS3?

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Networking :: BIND9 SLOW Ping When Ping By Hostname

Feb 1, 2011

I just installed my first EVER bind DNS server. I am running bind9 on Ubuntu 10.04. Everything seems to be working great except one thing: If I ping a host that I have set up in bind by its HOSTNAME the pings take 5-6 seconds to reply/print to the screen between each echo response. If I ping by the host's IP address, they echo back very quickly.

I have read that IPv6 can cause this, but I have disabled it in /etc/sysctl.conf and the problem still exists.

I know everyone says this can't be a DNS issue, but this never was an issue with dnsmasq (which i was using prior), and it doesn't make sense that the ping are ONLY slow when pinging by hostname and not IP.

Configs below:

Ping by hostname - there is a 5-6 second delay between each one of the responses:


Ping by IP - the responses come VERY quickly one after the other:







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Networking :: Can't Ping Past Gateway / Can Ping Server From Outside

Apr 29, 2010

So, I have an Virtual Machine running CentOS 5.4. It sits behind a hardware firewall which also does NAT'ing. I've set up plenty of these, so I know for sure the firewall and NAT rules are set up correctly. From the host, I can ping anything in my subnet and the gateway. But I can't ping anything else beyond the gateway. I can perform DNS queries and when I try to ping, it finds the appropriate IP address.But from the outside, I can ping the PUBLIC address (It's a 1 public to 1 private address NAT, not 1 public to multiple private). I've tried it with IPTABLES on and off, with no change.

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Networking :: Ping Connection To Router OK But No Ping Between Boxes In LAN

May 26, 2010

I have Mandriva One 2009.0 ( on one box and Mandriva Free 2010.0 ( on the other. I can ping router ( from both of these boxes but I can't ping one box to the other and the other way around. What's going on?.

Do I have to change some settings in router?. Or is it firewall issue on those two machines?. Both of these boxes are connected by cable. Symbol of the router: TL-WR340G.

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Ubuntu Networking :: Server Block ICMP By Default?

Jan 8, 2011

Installed Ubuntu Server 10.10, included Apache, PHP, and OpenSSH. Apache is up and serving pages, I can connect using PuTTY no problem. Server responds to a pingHowever, attempting to use ping or traceroute from the server results in a Destination Unreachable. Happens even for other boxes on the local network

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Networking :: Identify The Icmp Packet?

Dec 1, 2010

how to identify the icmp packets & marking. this below icmp packets marking is not working.

iptables -t mangle -A PREROUTING -p icmp -j MARK --set-mark 0x5
iptables -t mangle -A PREROUTING -p icmp -j RETURN

with the help of port no or any other how can i identify the icmp packet ?... This below two is working fine

iptables -t mangle -A PREROUTING -p tcp -j MARK --set-mark 0x2
iptables -t mangle -A PREROUTING -p tcp -j RETURN

iptables -t mangle -A PREROUTING -p udp -j MARK --set-mark 0x3
iptables -t mangle -A PREROUTING -p udp -j RETURN

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Networking :: ICMP Got Lower Priority?

Mar 16, 2010

I run a linux box as a gateway behind a satellite modem. The internet link over the satellite modem is only 1mbit so the usage often reaches 100% when someone is downloading/uploading something. I am seeing my ping return time jump from 700ms to 6000ms if someone tries to upload a file (by sending a attachment in a email etc). The satellite operator is saying this is normal, but I have my doubts.

Has ICMP got a lower priority? Should I really be seeing this behaviour? I understand that if it was a TCP packet then it would just be queued until the previous acknowledgement has been received. And if it was a UDP packet then it would have been dropped, but how does ICMP deal with these situations during heavy traffic?

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Networking :: Set ICMP TTL Exceeded Host?

Feb 20, 2011

Is there a way to set the IP that's returned in an ICMP TTL exceeded packet? Reason I ask is I have an edge router with several upstreams, and several downstream routers, and when I traceroute to it I would like only one of it's IP's to show up in the trace (Instead of each . Much like some of the larger ISP's do to mask the IP and hostname of their internal routers.. Is this possible?

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Networking :: Possible To Block ICMP To Particular Machine?

Jan 12, 2010

I have One Server which is having IP I want that client is not able to ping this server only & cane it is possible to block through hosts.

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Networking :: Why Linux Traceroute Use UDP Instead Of ICMP?

Jun 22, 2010

Why linux traceroute uses UDP protocol, we have basic ICMP protocol which is used in MS-windows tracert.Any specific use of traceroute using with UDP,TCP than ICMP?Windows is displaying all HOPs address but linux printing *.*.*

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Ubuntu Networking :: Disable ICMP Router Discovery For IPv6?

Jan 14, 2010

I set up a static IPv6 address and a gateway in /etc/network/interfaces. However, a bad router in my network environment alway send wrong ICMP router discovery messages to me. So I have got extra (wrong) IPv6 address and gateway, and the routing is confused. On Windows Servers, I can use "netsh interface ipv6 set interface "Local Area Connection" routerdiscovery=disable" to disable ICMP router discovery. But I don't know how to disable it on Ubuntu 9.10. How could I disable ICMP router discovery for IPv6?

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Networking :: How To Receive ICMP Messages In UDP Sockets

Jul 9, 2009

I have a C program which does.

1. Creates a UDP socket
2. Send the UDP Request packet to the TFTP server.
3. If the TFTP server is not listening in the 69 port, the remote machine send an ICMP ("Port Unreachable") message.

Is there a way to receive a notification from the Linux kernel on receipt of an ICMP packet to the created UDP socket.

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Networking :: ICMP Response Not Sent To A Local Network Ip?

Aug 19, 2010

icmp request from an ip that is in the same network as one of the local interfaces is not responded to, if the ping request is received via an interface in a different network. Is this some security feature?

Consider the below network

RTR - Router
x.1 -> 192.168.x.1
LNX - Linux machine


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Networking :: Get An Icmp Tunnel Setup Using Ptunnel

Jul 23, 2011

So im trying to get an icmp tunnel setup using ptunnel. When I run it under the same network and use to connect to RDP, it works fine, however when go outside my network and connect in, it does not get anywhere. I can confirm that I have forwarded ICMP packets to the server (if I ping the external ip it will show the status of the server if I unplug it) and that the server is showing signs of registering it.

On the client it just tries to resend the packet "Resending packet with seq-no 0" Over and over Firewall is off for testing so thats not the issue.

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Fedora Networking :: ICMP Redirect From Windows Gateway...

Sep 10, 2009

From what I've read, when linux sends a ping it sends without the netmask, so windows server assumes it must be a broadcast? Why doesn't linux send a netmask with a ping?

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Networking :: Why Firewalls Does Not Allow ICMP Echo Request Packets

Feb 8, 2011

Why firewalls does not allow ICMP echo request packets. Why are pings not allowed to certain systems?

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Networking :: Need ICMP / SNMP Based Monitoring Tool

Apr 21, 2010

Can any one tell me a network monitoring tool which can monitor remote connectivity and generate a comprehensive report about the link state like up/down, error timings, increase in latency and packet loss rate.

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