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.
I'm facing a strange problem. I have a Debian squeeze machine connected to Internet through a 3G USB modem. The machine connects as expected, and I can resolve domain names and establish HTTP and SSH connections.The problem is when I try to communicate to that machine from another PC connected to Internet. The machine doesn't respond to PING and I can't connect to the SSHD installed in it. If I connect the machine to the local network, it works right.
route:
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
default * 0.0.0.0 U 0 0 0 ppp0[code]...........
I created a new account on laposte.net.
This account can receive messages but cannot send any from Thunderbird.
[url]
How can I disable ICMP messages through the configuration file of /proc/sys/net/ipv4/ICMP_echo_ignore_all Also how the above file can be edited?
View 1 Replies View RelatedI have a small LAN. I am in the process of installing a Debian Lenny/Squeeze system into the LAN. I want to send and receive system messages using rwalld and wall.I can send a system message from my Debian system to another box using rwall. I can send a local message within the Debian box using wall in a console.I cannot send a local message using wall Konsole in KDE 3.5.x. The KDE Write daemon fails to provide any pop-up window./usr/bin/wall is installed from the bsdutils package and is set to -rwxr-sr-x.
The ktalkd package is installed. The KDE control center shows a configuration option in Internet & Network settings called Local Network Chat.When not in X, mesg is set to y at the console. After starting KDE and I open Konsole, mesg is always set to n. I don't know how this setting toggles. Further, setting mesg to y in Konsole has no effect on getting wall to work.mesg is set to y when I run xterm in KDE. Then wall works within that terminal window. However, the KDE Write daemon does not see the message in xterm.When I send a message from another system to the Debian system using rwall, xterm receives the message but not Konsole or the KDE Write daemon.
When I send a wall message from Konsole, xterm receives the message but not Konsole or the KDE Write daemon.I changed TTYPERM in login.defs to 0620 to no avail.I do not have this problem on the non-Debian systems.
I have a small LAN. I am in the process of installing a Debian Lenny/Squeeze system into the LAN. I want to send and receive system messages using rwalld and wall.I can send a system message from my Debian system to another box using rwall. I can send a local message within the Debian box using wall in a console.I cannot send a local message using wall Konsole in KDE 3.5.x. The KDE Write daemon fails to provide any pop-up window./usr/bin/wall is installed from the bsdutils package and is set to -rwxr-sr-x.
The ktalkd package is installed. The KDE control center shows a configuration option in Internet & Network settings called Local Network Chat.When not in X, mesg is set to y at the console. After starting KDE and I open Konsole, mesg is always set to n. I don't know how this setting toggles. Further, setting mesg to y in Konsole has no effect on getting wall to work.mesg is set to y when I run xterm in KDE. Then wall works within that terminal window. However, the KDE Write daemon does not see the message in xterm.When I send a message from another system to the Debian system using rwall, xterm receives the message but not Konsole or the KDE Write daemon.
Just another newbie question here, I've recently changed my main OS to ubuntu 9.10 and everything is going swimmingly.Except a small problem with empathy IM. I have seen posts where people complain about it not being able to set its status to hidden for MSN, this is not what my problem is.My problem is as follows: when friends of mine who's status is set to hidden on MSN (them using windows and default MSN app) message me, I receive no such messages. They have to set the status to visable to be able to message me at all.
On XP I used Digsby, it could recieve such messages normally. So I am not sure if it is due to empathy being a 3rd party app.
I have USB modem huawei1550 and it work nice but I have one problem that I cant send or Receive messages because my pc dont recognize my usb as usb modem.
View 2 Replies View RelatedI'm trying implement a small server for a university work, my server is creating, binding and listening but it don't accept any connection, these are the files I'm using in server:
Code:
// Definition of the Socket class
#ifndef SOCKET_H
#define SOCKET_H
#include <sys/types.h>
code....
I've made a client just for test it, but no ones run well, the server is always returning -1 when accept is called!!
What should I do to send and receive messages in this server??
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.
View 1 Replies View Relatedhow 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
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?
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?
View 2 Replies View RelatedI have One Server which is having IP 10.176.0.155. I want that client 10.176.0.135 is not able to ping this server only & cane it is possible to block through hosts.
View 1 Replies View RelatedWhy 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 *.*.*
View 8 Replies View Relatedicmp 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
x.1|RTR1|-y.1---------y.2-|RTR2|-z.2------z.3-|LNX|-x.3
RTR - Router
x.1 -> 192.168.x.1
LNX - Linux machine
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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.
What's the total no. that the OS can create? Does this differ from 32-bit?
View 1 Replies View RelatedFrom 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?
View 6 Replies View RelatedI tried to ping some of the pcs on the local network but for those with icmp disabled it doesn't work. I've used
Code:
nmap -sP 192.168.2.0/24
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 192.168.1.10x boxes on the local network
View 1 Replies View RelatedWhy firewalls does not allow ICMP echo request packets. Why are pings not allowed to certain systems?
View 1 Replies View RelatedCan 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.
View 3 Replies View RelatedOn my system, I have built my own tunneling protocol, where I relay packets over a non-standardized but verified medium. What I do is capture the packets using iptables and NFQUEUE, relay them over my medium, and at the other end I reinject them using raw sockets. The packet going into the tunnel is exactly the same as the one coming out, verified. The problem is that this doesn't work for ICMP Ping (Echo Request) if the destination of the ping is the same as the tunnel endpoint. If the destination is not the same as the tunnel endpoint, the ping packet is rerouted and arrives as it should at the receiver, and the ping reply comes back to the sender. Does anyone know whats going on? Isn't it possible to send raw icmp to yourself? If not, anyone have an idea what I should do instead?
View 1 Replies View RelatedI 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?
View 4 Replies View RelatedWhen 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?
Struggling to get my Linux server accept ICMP redirects not originating from default gateway. No problem to get it working if the redirects is originating from def gw.I know it's not a good solution security wise, but my network is so cluttered I'm forced to do so.
View 1 Replies View RelatedI 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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Hi ,
I created a socket.port no 21 meaning ftp client.
I am sending some stings and receviing some data from server.Fine.
But I want to send a file some x.c to host using socket.
Please can someone help me whether we can do it or not.
If we can how can we send a file.I was only able to send buffer and data but not a file.Please if possible can you help me with example.
Regards,
shaiva
The problem started when I noticed I couldn't upload to people using a torrent downloading program, the program listened on port X and when I sniffed on the same port I saw that syn's are forwarded correctly from my nat to that port but the program doesn't relate to those packets. Then I listened with NC, and even on another port nothing is being answered to those syns packets.
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