Networking :: Socket Programming - Connect To Port Y On IP X With Telnet
Sep 16, 2010
I have a customer who is complaining that they can connect to prt y on IP x with telnet. They are seeing the following:
telnet x.x.x.x y
Trying x.x.x.x...
Connected to x.x.x.x.
Escape character is '^]'.
after some time the connection of course times out. Connection closed by foreign host. There is no telnet service running on this port so they cannot do anything, but they are complaining tht the fact that telnet "connects" is a security risk. I am having difficulty explaining why they are able to connect with telnet. I know it has to do with the socket layer API in Linux but I am having difficulty explaining this sufficiently. I also can't just say "this is the way linux works" to them. I am looking through "UNIX Network Programming" by W.
I have an x application I am trying to run under gnome. It assumes a fixed ip address and exclusive use of the eth0. I have run it under gnome on RHEL 5.3. I set the ip address and ifconfig confirms the correct address. When I run it I get "SocketConnect() error:
Resource temporarily unavailabele, port 8005. (on the terminal that I started it)
This is indicative that it has failed to make a connection to the outside world. One difference I notice between the non-working and the working is that, the error message seems to stop coming out on the fedora gnome, almost immediately, whereas on the other installations it will come out indefinitely until it connects. is virb0 interferring. What is different in the networking on fedora 11 then RHEL?
I make an application on GNU/Linux which listening on a MULTICAST stream, so I open my unconnected socket, bind it on a MULTICAST address and a port, join the multicast group with the "setsockopt (IP_ADD_MEMBERSHIP)", then I receive datagram on my socket.
Now I've two different instances of the same application that run with their own MULTICAST address and port. And what I found strange is that, after a misconfiguration, I switch the ports, for example:
Emitting on 225.0.0.1/23451 and 225.0.0.2/23452 Receiving on 225.0.0.1/23452 and 225.0.0.2/23451
And my receiving part doesn't care about the MULTICAST address, it looks like the socket is listening on the port number only! I mean that the receiver [225.0.0.1/23452] take its datagrams from emitter [225.0.0.2/23452] and vice-versa!
Is it possible to swap a client ip and port ? This is what I am trying to do. Let say you have Comp1 and Comp2 And you have Server between them. My goal is to get Comp1 and Comp2 know each others IP So Comp1 connects to server And server stores comp1's IP In a text file or other place And Comp2 connect to server And server also stores his info And then both comp1 and comp2 dowload the tex file And use the info on it.
Elementary... Here's the tricky part: next i have to handle user level ack the server is sending to "client"... To do that i have to open server socket on the same port number the system assigned to my client socket before. How can i get it ( in user level code)?
I'm using a single raw socket to read UDP packets from local test network with 1024 ports. Each UDP src and dest port is unique and I need access to IP and UDP header fields. I can stream and process data (in and out) at 100 mbps in linux-rt kernel with very low jitter < 250 usec, 10 usec nominal.
I'd like to prevent kernel from issuing ICMP port unreachable errors back to the sending host, however, I don't want to create 1024 vanilla UDP sockets and bind to each one because of resource constraints. Currently, I'm using iptables to drop the outbound port unreachable messages. Does anyone know of a way (programmatic using C code) to prevent the ICMP unreachable traffic? Perhaps an IOCTL or socket option? I also tried changing /proc/sys/net/ipv4/icmp_ratelimit but that seemed to have no effect. By default the ratemask is set for dest unreachables and a variety of ratelimit values did not change any behavior that I could see.
I am trying to create a socket to listen for a bootp response so I am using a PF_PACKET socket so that I get the response based on my mac. My problem is that I don't want to hear all traffic (as I do now) so would like to use a specific port number and bind to it.
I am learning network prgramming in linux in c,and try to build a server and in this server I want to bind the listening socket to a paricular Ip address and port.Bind function is showing error,I did not want to use wild card. Here is the code.
If I open a raw SCTP socket, am I able to bind to a specific port? (I only want to see SCTP packets from a particular IP address AND port.) Or, any raw SCTP socket, regardless of port binding , will get all SCTP packets received by the OS from that IP address? The port doesn't matter and is ignored.
I want to create script wherein it will check the application if its running. The command that I'll be using to check the application is telnet (if you can recommend others, that's ok). I've an application and it is listening to port 1808. If I do telnet localhost 1808, the response is :
What I want to happen is if the response is like to code above, it will execute a commands. Obviously, above code knows that the application is not working so I need to execute a commands. I created a script before using expect but I don't think it will work because I haven't establish a shell yet unlike successful telnet I could spawn expect.
I am looking to be able to connect to an IRC server in a C program. I have followed some instructions from an old book I have however it doesn't seem to be working. I've tried connecting to localhost on my ssh port and it still doesn't want to work. This is what I have so far as a piece of skeleton test code:
Trying 192.168.100.9... telnet: Unable to connect to remote host: Connection refused
[Code].....
This last one is strange as I the IP looks odd.
What I am doing wrong, and how do I fix it. After much surfing many mosts say that telnet is not used anymore but I want to use it to test my smtp server.
iam just trying to connect to server which accepts one client and server will read(blocking operation) infinitely, but After closing the client socket the server "read operation" is returning zero and "errno variable(in errno.h)" value is also zero. how can i detect whether a client socket is closed/active..?
is it possible using a perl script to test for a socket listening on a UDP port on a remote host ?I work in an environment where netcat is not allowed and from time to time I need to see if a UDP port is open on a remote host.
I'm using mysql server through tcp/ip with no problem. But I don't know since when I'm not able to connect through socket. There are lots of topics but my bad I couldn't find one works for me.
OS: Ubuntu 9.04 mysql 5.0.75-0ubuntu10.5
my.cnf
Quote:
[mysqld] user = mysql socket = /var/run/mysqld/mysqld.sock skip-name-resolve safe-show-database code....
/var/run/mysqld/mysqld.sock socket exists and has chmod 777 Error:
Code: ERROR 2002 (HY000): Can't connect to local MySQL server through socket 'localhost' (2)
I am running CentOS 5.1 on VMware on Win 7 On CentOS I added Bridged network adapter and the server is connected to internet without any problems, but when I telnet any server on port 25 I get connection timeout.
Code:
telnet f.mx.mail.yahoo.com 25 Trying 98.137.54.237... telnet: connect to address 98.137.54.237: Connection timed out telnet: Unable to connect to remote host: Connection timed out
I stopped all servers, iptables and sendmail on the linux server and the firewalls on the win 7 but still getting the same error! I added new network adapter ( host-only ) and tried to telnet the win machine from vmware Linux but I got connection refused
Code:
telnet 192.168.71.1 25 Trying 192.168.71.1... telnet: connect to address 192.168.71.1: Connection refused telnet: Unable to connect to remote host: Connection refused
the above code works fine.if we copmile and run ./a.exe 192.xx.xx.xxx 1111 and press enter it works fine..everytime it asks "Please enter the message: " and if give that will be displayed in server. but my problem is i dont want to print everytime "Please enter the message: " i just want to feed some words one by one to the socket.
im getting that error in my code for some reason. I compiled my code, and when i try to run this server it throws me an error on my call to setsocketopt(). The only way it can reach that part of my loop is if it succeeds when it calls sock() so I dont understand why the error says its an operation on a non-socket. Im just trying to set up a server to pass messages from a client to it a viceversa. Here is the code:
Code: int main() { int socket_fd, new_socket_fd, k; struct addrinfo hints, *server_info, *p; struct sockaddr_storage peer_address; code....
I am having problems accessing my work desktop through my home computer running Fedora 13. I am able to remote into work through MAC and Windows XP. I loaded vpnc and was able to connect to the concentrator. I also able to ping it too. I cannot connect to my desktop using rdesktop. I get error message �Unable to connect, socket is unavailable. I cannot ping to the desktop.
Right now I have a machine set up running Fedora. I have configured inittab to accept Console Logins, but I am having problems getting my netbook running PuTTY to connect. How would I go about finding the Host Name and Port to connect to?
I am trying to find the difference between the above two services. Both are under xinetd and can someone please explain the difference between them (is one more secure than the other one?)
I'm trying to make an SSH script for my place of employment. This script, I want to go out to the server hostnames we have specified (in another file) and change a users account password. We use Kerberized telnet, so if telnet root hostname fails, I want it to use ssh username hostname and use the old password (specified). If both fail, I want it to ask the user what the port should be and input the port in the ssh command.
But I'm having a issue having it try telnet root hostname and if it fails then, try to ssh in, I have no clue how to have it proceed. Is it an if statement? Here's the telnet failed message: telnet: Unable to connect to remote host: Connection refused
I want to configure socket timer to release socket(port) once the connection is terminated. Do we have something in Linux OS to configure this delay to release socket?.
Any command, link or man-page anything will be helpful.
Linux 2.6.27.5-117.fc10.i686.PAE #1 SMP Tue Nov 18 12:08:10 EST 2008 i686 i686 i386 GNU/Linux
I need to enable telnet service on it, then found xinetd and telnet-server not installed,
Then I had installed below First I had installed Xinetd: xinetd-2.3.14-21.fc10.i386.rpm then I had installed telnet-server: xinetd-2.3.14-21.fc10.i386.rpm
After installation I executed below commands
Service xinetd start Chkconfig xinetd on Chkconfig telnet on Service iptables stop Chkconfig iptables off Iptables �F
After I had tried telnet localhost ----IT FAILED
when I run telnet server manually by issuing the below command /usr/sbin/in.telnetd, I get below error [COLOR="Red"]/usr/sbin/in.telnetd: getpeername: Socket operation on non-socket[/COLOR]
I have other system running same OS, I had followed the same steps discussed above to enable telnet, It works fine on it.
