i see... 32 bit is for ip , and 16 bit is for port. one quicky question: ip address consists of 2 parts, one is network address, the other is host address. since unix.com is at 81.17.242.186, what is its network as well as its host address ?
How do you or what is the setup to keep the (server) up from shutting down? It is not server yet but it might very likely become to serve few clients. But, once I get in in the morning its off. It's Sparc, Solaris 8 and I would like to keep it running over night but once it is not attended it... (2 Replies)
I'm using AF_INET in sockets for inter process communication on the same machine. Is AF_UNIX better for IPC on the same machine than AF_INET in terms of performance? If so, how much better? I would like to know if there is sample code available to test this. I'm running the program on Solaris.
... (0 Replies)
Hi all,
I am working on following script which is already working and i am trying to understand but could not can any body help me in follwoing script.
I understand that it deletes record from tables. using DB2 import from /dev/null. I dont know where in second portion it loads the data in to... (0 Replies)
I have a HP-UX11i machine on the network and that works fine.
But, now i want to start this machine without network connection?
How must i do this?
Because, if i pull out the network cable it will not boot. (5 Replies)
Greetings!
I am attempting to write a *basic* network client in C. I have manage to create a socket but I have doubts as far as using AF_INET vs AF_UNIX.
At the present time, my client runs with AF_INET. Is AF_UNIX faster across hosts using the same OS flavor (Red Hat)? What is the difference... (1 Reply)
Hi all,
During reading the code, i met such expressment in a KSH script. I can not figure out what does this mean and don't know how to search it in the web. Could you please check below snippet and let me know what does this mean in a shell script:
VARIABLE=1
if ; then
.... (3 Replies)
**this was posted in another forum I suspect wrong one moved here **:confused:
Hello all. Let me qualify my question by saying that I am struggling with how to ask the question I am semi green but have no issue reading up if pointed in the right direction. Please be gentle!
A RHEL server 6.2.... (4 Replies)
Discussion started by: rsheikh01
4 Replies
LEARN ABOUT DEBIAN
dhcping
dhcping(8) General Commands Manual dhcping(8)NAME
dhcping - send a DHCP request to DHCP server to see if it's up and running
SYNOPSIS
dhcping [-v] [-q] [-i] [-r] -t maxwait -c client-IP-address -s server-IP-address -h client-hardware-address [-g gateway-IP-address]
DESCRIPTION
This command allows the system administrator to check if a remote DHCP server is still functioning.
Options are:
-v Verbose, print some information.
-V Very verbose, print a lot of information.
-i Use DHCPINFORM packets.
-r Use DHCPREQUEST packets (default behaviour).
-q Quiet, print nothing on the screen.
-t maxwait
Maximum time to wait for an answer from the server in seconds. Default is 3 seconds.
-c client-IP-address
Request this IP address. Note that this is also the IP address the answer will be sent to.
-s server-IP-address
Send the DHCP packet to this IP address.
-h client-hardware-address
Use this hardware-address in the DHCP request. It can be up to sixteen octets separated by colons (i.e. 01:02:03:04)
-g gateway-IP-address
Use this IP address for the gateway IP address in the DHCP packet. This option is currently broken.
RETURN VALUES
If everything goes okay, it returns 0. If there went something wrong, it returns 1.
SETUP
This program should be installed setuid root or ran by root only. See SECURITY for more information.
On your DHCP server, add these lines to the dhcpd.conf:
host <your monitoring host FQDN> {
hardware ethernet <your monitor host mac address>;
fixed-address <your monitoring host IP address>;
}
Then try it:
$ dhcping -c your monitoring host IP address
-s your DHCP server IP address
-h your monitor host mac address
It will either respond with "no answer" or "Got answer from: your DHCP server IP address"
The DHCP server logfile will give:
DHCPREQUEST for 192.168.1.1 from 00:20:18:56:29:8f via ed0
DHCPACK on 192.168.1.1 to 00:20:18:56:29:8f via ed0
DHCPRELEASE of 192.168.1.1 from 00:20:18:56:29:8f via ed0 (found)
Running in DHCPINFORM mode with -i:
If you see "DHCPINFORM from 192.168.1.1 via xl0: not authoritative for subnet 192.168.1.0", you should add the authoritative statement to
the subnet, See dhcpd.conf(5) for details.
When running in very verbose mode, dhcping tries to dump all data of the send and received DHCP packets. It will first dump the packet in
hex-format, then decodes the header and finally the options.
HOW IT WORKS
The client either sends a DHCPREQUEST or DHCPINFORM packet to the server and waits for an answer. Then, if a DHCPREQUEST was send, it will
send a DHCPRELEASE back to the server.
SECURITY
This program is installed setuid root as it requires the privileges to bind itself to port 68 (bootpc). Root privileges are dropped as soon
as the program has bound itself to that port.
BUGS
Currently (this may, or may not, change in the future) the ISC DHCP daemon does not write leases with a fixed IP address in the
dhcpd.leases file.
DHCPINFORM packets can only be used on subnets the server is authoritative for. If the monitoring script runs on a subnet the server isn't
authoritative for, it should use the DHCPREQUEST packets. I also experienced some problems with ISC DHCPD v2 servers, but that is also in
the README of it.
The -V option is still working, but shouldn't be used for debugging of the packets. Better use dhcpdump(8) for that, which is available on
my website. I wanted to remove it, but decided only to do it from the documentation, not from the code. Maybe I'll need it one day for
debugging.
AUTHOR
Edwin Groothuis, edwin@mavetju.org (http://www.mavetju.org)
SEE ALSO dhcpd(8), dhclient(8), dhcpd.conf(5), dhcpdump(8)3rd Berkeley Distribution January 27, 2002 dhcping(8)