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• Ip address to country with database

  - by newbie

  I have downloaded ip-to-country.csv that has ip ranges that are mapped to countries. How should I store this data to database and how can I query in what range Ip address is to know where Ip address is coming from?

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• Allocation of IP Address in Ad hoc systems

  - by Kasturi

  Me and my friends play Age of Empires every weekend and create an Ad-hoc network each time before playing. But each time we all get the SAME IP Address even if a new ad-hoc network is created. Is this something to do with the Game's algorithm or does the laptop remember our previous IP Address. EDIT: What is the algorithm that is used to distribute the IP Addresses? If the algorithm uses random function how come same IP addresses are being allocated.

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• need an ip location lookup

  - by Tuffy G

  anyone know of a decent site where i can lookup where an ip address is? e.g. if i have ip address x.x.x.x.x and i want to know if that ip is in london or scotland. i've been going around google and what the sites i have found are saying is that ip x is located in location london when it shud be roughly 250 miles away from there. thanks p.s. must be free

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• iptables -P FORWARD DROP makes port forwarding slow

  - by Isaac

  I have three computers, linked like this: box1 (ubuntu) box2 router & gateway (debian) box3 (opensuse) [10.0.1.1] ---- [10.0.1.18,10.0.2.18,10.0.3.18] ---- [10.0.3.15] | box4, www [10.0.2.1] Among other things I want box2 to do nat and port forwarding, so that I can do ssh -p 2223 box2 to reach box3. For this I have the following iptables script: #!/bin/bash # flush iptables -F INPUT iptables -F FORWARD iptables -F OUTPUT iptables -t nat -F PREROUTING iptables -t nat -F POSTROUTING iptables -t nat -F OUTPUT # default default_action=DROP for chain in INPUT OUTPUT;do iptables -P $chain $default_action done iptables -P FORWARD DROP # allow ssh to local computer allowed_ssh_clients="10.0.1.1 10.0.3.15" for ip in $allowed_ssh_clients;do iptables -A OUTPUT -p tcp --sport 22 -d $ip -j ACCEPT iptables -A INPUT -p tcp --dport 22 -s $ip -j ACCEPT done # allow DNS iptables -A OUTPUT -p udp --dport 53 -m state \ --state NEW,ESTABLISHED,RELATED -j ACCEPT iptables -A INPUT -p udp --sport 53 -m state \ --state ESTABLISHED,RELATED -j ACCEPT # allow HTTP & HTTPS iptables -A OUTPUT -p tcp -m multiport --dports 80,443 -j ACCEPT iptables -A INPUT -p tcp -m multiport --sports 80,443 -j ACCEPT # # ROUTING # # allow routing echo 1 >/proc/sys/net/ipv4/ip_forward # nat iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE # http iptables -A FORWARD -p tcp --dport 80 -j ACCEPT iptables -A FORWARD -p tcp --sport 80 -j ACCEPT # ssh redirect iptables -t nat -A PREROUTING -p tcp -i eth1 --dport 2223 -j DNAT \ --to-destination 10.0.3.15:22 iptables -A FORWARD -p tcp --sport 22 -j ACCEPT iptables -A FORWARD -p tcp --dport 22 -j ACCEPT iptables -A FORWARD -p tcp --sport 1024:65535 -j ACCEPT iptables -A FORWARD -p tcp --dport 1024:65535 -j ACCEPT iptables -I FORWARD -j LOG --log-prefix "iptables denied: " While this works, it takes about 10 seconds to get a password promt from my ssh command. Afterwards, the connection is as responsive as could be. If I change the default policy for my FORWARD chain to "ACCEPT", then the password promt is there imediatly. I have tried analysing the logs, but I can not spot a difference in the logs for ACCEPT/DROP in my FORWARD chain. Also I have tried allowing all the unprivileged ports, as box1 uses thoses for doing ssh to box2. Any hints? (If the whole setup seems strange to you - the point of the exercise is to understand iptables ;))

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• Users not getting ip when connected through wifi,but wired connection getting ip in ddwrt router

  - by Kevin Parker

  I am having DD-WRT v24-sp2(05/08/11) running on Asus RT n 13 u B1 router,with dhcp on. But users not able to connect through wifi...its showing obtaining ip address and disconnects there after. Wired Devices are getting ip address and able to access internet.Wifi was working till yesterday,but all of a sudden it stopped working. on the ddwrt controlpanelsystem information under Wireless Clients mac address of clients that are trying to connect are appearing but soon it disappears. but no such issue with wired clients. Can any one please help me in fixing this..

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• Search network device from LAN through my C++ application and change the IP address

  - by Arun Kumar K S

  I am developing an application in C++ to communicate with my network device. I used UDP classes to search the device from the network. I done the code in such a way that from my application a broadcast message will send to the local network. The device will respond to the broadcast message and the application will get the IP address from that response. After establishing a network communication send a message to the device for changing the IP address. That worked fine if my devices IP address is correct. But when I set a wrong IP address and subnet to the device. My application will never get any messages from the device. So I can't able communicate to the device and not able get the device and unable to change the IP address etc. Say example IP address of the device 20.1.1.1 Subnet Mask 255.0.0.0 And in my system that runs the application IP address 192.168.1.23 Subnet Mask 255.255.255.0 I tried the Lantronix device installation software with their Lantronix device in network. It listed the device from the network and I am able to change the IP address from their software. Any one know how this is done in this type of software? How I can search in network to find the device and change the IP address when its IP address is not in range? Which protocol they used to find the device?

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• Windows Firewall allows connection from any IP regardless of rule that only allow a specific IP

  - by Pierre-Alain Vigeant

  I have configured the Windows Firewall to Block (default) incoming connection on the public profile. I have created a rule for a port (in this case, this is Sql Server) that explicitly states that only my office static IP is allowed. If I test from my office, I am able to connect to the port. I was expecting that anybody outside the office would not be able to connect, but this is not the case. I asked a friend to telnet the port to see if it would reply and it does even if he's not on my network. I am a bit confuse here. Shouldn't it block everybody but the given IP? Is my server completely unsecured?

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• parsing ip address in php

  - by Ryan

  Hi all, I am trying to create a page that shows the user their zip code when they are on my page. (if any of you are familiar with GeoIP data, thats what I am using. ) I have a conversion that converts the users IP address into an IP number, that conversion is: ipnum = 16777216*w + 65536*x + 256*y + z where w.x.y.z are the ip sections (000.000.000.000) My question is, using $_SERVER['REMOTE_ADDR']; is there a way for me to section the users ip address and assign the section of the ip address to variables? for example: usersip = 192.168.123.5 w = 192; x = 168; y = 123; z = 5; Thanks!

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• Cannot redirect ip traffic with iptables to new ip on linux centOS

  - by Kiwi

  today I able to migrate some of the game servers to another server and needed some help to redirect the traffic from old ip to the new one. SERVER1 1.1.1.1 ----- (internet ) ----- SERVER 2.2.2.2 I asume to use iptables to perform this, for that used this rule on my centOS box in the server1. /etc/sysctl.conf: net.ipv4.ip_forward = 1 iptables -t nat -A PREROUTING -p udp --dest 1.1.1.1 --dport 27015 -j DNAT --to-destination 2.2.2.2:27015 iptables -t nat -A POSTROUTING -j MASQUERADE iptables -t nat -A POSTROUTING -d 2.2.2.2 -p udp --dport 27015 -j SNAT --to 1.1.1.1 But the client cannot connect to the server from the old ip, the redirection don't started.

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• How do you make sure your pakcet is delivered to right client using public ip address

  - by TemporaryNickName

  So private IP addresses are 192.168.00 ~ 192.168.255.255 or 10.0.0.0 or 172.16.0.0 ~ 172.31.255.255 If I accepted a client to my serversocket, I can get the client's remoteIp address by using socket.getremotesocketaddress(); But I suspect the IP address that I'm getting from this method is only the public IP address and it must have more than one client using same public IP as this one (one like you see when you go on to the website www.whatismyip.com). So if I want to make sure that my packet is delivered to the right person using some IP address or otherthing that uniquely identifies a person, what should I have to do?

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• [php + mysql] Save IP in database

  - by Knarf

  When a user logs inn I want to save their IP in the database. How would I do that? What type is best to use for the MySQL field? How would the PHP code to get IP look like? I'm thinking of using it as an extra security feature for the login/session stuff. I'm thinking of checking the IP the user logged in with from the DB with the IP the user have now as addition to checking the session. So that it first check the session, and then check if you have a valid IP. Is that an allright extra feature? And what other things can I do to make it more secure?

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• Trying to reconcile global ip address and Vhosts

  - by puk

  I have been using my local machine as a web server for a while, and I have several websites set up locally on my machine, all with similar Vhost files like the one seen here /etc/apache2/sites-available/john.smith.com: <VirtualHost *:80> RewriteEngine on RewriteOptions Inherit ServerAdmin [email protected] ServerName john.smith.com ServerAlias www.john.smith.com DocumentRoot /home/john/smith # Possible values include: debug, info, notice, warn, error, crit, # alert, emerg. LogLevel warn LogFormat "%v %l %u %t \"%r\" %>s %b" comonvhost CustomLog /var/log/apache2/access.log comonvhost </VirtualHost> then I set up the /etc/hosts file like so for every Vhost: 192.168.1.100 www.john.smith.com john.smith.com 192.168.1.100 www.jane.smith.com jane.smith.com 192.168.1.100 www.joe.smith.com joe.smith.com 192.168.1.100 www.jimbob.smith.com jimbob.smith.com Now I am hosting my friend's website until he gets a permanent domain. I have port forwarding set up to redirect port 80 to my machine, but I don't understand how the global ip fits into all of this. Do I for example use the following web site addresses (assume global ip is 12.34.56.789): 12.34.56.789.john.smith 12.34.56.789.jane.smith 12.34.56.789.joe.smith 12.34.56.789.jimbob.smith

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• VPS with Plesk, one ip, and godaddy (definely need help)

  - by Francesco

  Hi there, here's my situation : i've Plesk 8.3.0 with one IP and i've registered my domains at godaddy.com My problem : i cannot figure out how to configure plesk and godaddy to have my domains (6) properly working into the VPS. i've only one IP, so i can't have my personal NS and need to use godaddy ns. But.. how do i set all the stuff ? I've made a try but it's not working. Please take a look : This is an example of how the domain i'm actually working on is configured On Plesk : Host Record type Value 1.2.3.4 / 24 PTR mydomain.com. ftp.mydomain.com. CNAME mydomain.com. mail.mydomain.com. A 1.2.3.4 ns.mydomain.com. A 1.2.3.4 mydomain.com. NS ns.mydomain.com. mydomain.com. A 1.2.3.4 mydomain.com. MX (10) mail.mydomain.com. webmail.mydomain.com. A 1.2.3.4 www.mydomain.com. CNAME mydomain.com. On godaddy,(Total DNS Control) for the same domain i have this setup : A (Host) Host Points To TTL Actions * 1.2.3.4 1 Hour CNAMES (Aliases) Host Points To TTL Actions e email.secureserver.net 1 Hour email email.secureserver.net 1 Hour ftp @ 1 Hour imap imap.secureserver.net 1 Hour mail pop.secureserver.net 1 Hour mobilemail mobilemail-v01.prod.mesa1.secureserver.net 1 Hour pda mobilemail-v01.prod.mesa1.secureserver.net 1 Hour pop pop.secureserver.net 1 Hour smtp smtp.secureserver.net 1 Hour webmail webmail.secureserver.net 1 Hour www @ 1 Hour MX (Mail Exchange) Priority Host Goes To TTL Actions 10 @ mailstore1.secureserver.net 1 Hour 0 @ smtp.secureserver.net Host Points To TTL Actions @ ns53.domaincontrol.com @ ns54.domaincontrol.com What should i correct ? Thanks for helping me Francesco

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• Running two different websites domains one one IP address

  - by Akshar Prabhu Desai

  Here is my apache configuration file. I have two domain names running on same ip but i want them to point to different webapps. But in this case both point to the one intended for e-yantra.org. If I copy paste akshar.co.in part before E-yantra.org both start pointing to akshar.co.in I have two A DNS entries (one per domain name) pointing to the same IP. NameVirtualHost *:80 <VirtualHost *:80> ServerName www.e-yantra.org ServerAdmin [email protected] DocumentRoot /var/www <Directory /> Options FollowSymLinks AllowOverride All </Directory> <Directory /var/www/> Options Indexes FollowSymLinks MultiViews AllowOverride All Order allow,deny allow from all </Directory> <Directory /var/www/ci/> Options Indexes FollowSymLinks MultiViews AllowOverride All Order allow,deny allow from all </Directory> <Directory /var/www/db2/> Options Indexes FollowSymLinks MultiViews AllowOverride All Order allow,deny allow from all </Directory> ScriptAlias /cgi-bin/ /usr/lib/cgi-bin/ <Directory "/usr/lib/cgi-bin"> AllowOverride None Options +ExecCGI -MultiViews +SymLinksIfOwnerMatch Order allow,deny Allow from all </Directory> ErrorLog /var/log/apache2/error.log # Possible values include: debug, info, notice, warn, error, crit, # alert, emerg. LogLevel warn CustomLog /var/log/apache2/access.log combined Alias /doc/ "/usr/share/doc/" <Directory "/usr/share/doc/"> Options Indexes MultiViews FollowSymLinks AllowOverride None Order deny,allow Deny from all Allow from 127.0.0.0/255.0.0.0 ::1/128 </Directory> </VirtualHost> <VirtualHost *:80> ServerName www.akshar.co.in ServerAdmin [email protected] DocumentRoot /var/akshar.co.in <Directory /var/akshar.co.in/> Options Indexes FollowSymLinks MultiViews AllowOverride All Order allow,deny allow from all </Directory> </VirtualHost>

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• Varnish configuration, NamevirtualHosts, and IP Forwarding

  - by Brent

  I currently have a bunch of NameVirtualHost based websites, load balanced between 3 apache2 servers using ldirectord. I would like to insert varnish as a reverse-web-proxy between ldirectord and apache in the following way: a request comes in to ldirectord it is then load balanced between the 3 apache2 servers and varnish, with a weight of 1 for the webservers, and 99 for varnish (so if varnish is rebooted, the webservers will take over seamlessly) varnish will then load balance its requests between my apache2 servers. However, the varnish part is not working. I wonder whether this has to do with the fact that my apache servers use x.x.x.x:80 for their NameVirtualHosts, instead of *:80? (they have to do this, since each server hosts multiple IP addresses) Or perhaps it has to do with the need for IP Forwarding to be set up on the varnish server? (I did echo 1 /proc/sys/net/ipv4/ip_forward on this server, is that sufficient?) How can I debug this problem? ldirectord doesn't produce logs of what it does with each request (and if it did, I would be overwhelmed with information since I'm serving hundreds of requests per second) varnish log shows the ldirectord server connecting to it every 5 seconds, but nothing else. I have set up a test site using this configuration, but it fails - no apache access logs, no applicable varnish logs.

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• Force local IP traffic to an external interface

  - by calandoa

  I have a machine with several interfaces that I can configure as I want, for instance: eth1: 192.168.1.1 eth2: 192.168.2.2 I would like to forward all the traffic sent to one of these local addresses through the other interface. For instance, all requests to an iperf, ftp, http server at 192.168.1.1 should be not just routed internally, but forwarded through eth2 (and the external network will take care of re-routing the packet to eth1). I tried and looked at several commands, like iptables, ip route, etc... but nothing worked. The closest behavior I could get was done with: ip route change to 192.168.1.1/24 dev eth2 which send all 192.168.1.x on eth2, except for 192.168.1.1 which is still routed internally. May be I could then do NAT forwarding of all traffic directed to fake 192.168.1.2 on eth1, rerouted to 192.168.1.1 internally? I am actually struggling with iptables, but it is too tough for me. The goal of this setup is to do interface driver testing without using two PCs. I am using Linux, but if you know how to do that with Windows, I'll buy it!

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• Multiple IP's using one NIC connectivity problem - Windows

  - by Vincent

  I have a frame relay network that is directly connected to a GPRS network. I also have a ADSL high speed network and recently I have been trying to achieve the following network configuration using windows 7 (Also tried XP) with no success to date. On one server I have two NIC's NIC1 I would like the following two static IP address's 10.0.1.110 and 10.0.1.200 the cisco router has a default gateway of 10.0.1.1 the ADSL is DHCP. NIC1 and the cisco router do not have access to the internet. NIC2 is setup for DHCP with a primary DNS and secondary DNS configured to enable internet connectivity. With NIC1 all incoming TCP connections are from IP address's starting with 10.192.x.x I cannot establish a TCP connection to both 10.0.1.110 and 10.0.1.200. Its either one or the other. I have a static route implemented in windows of: route -p 10.192.0.0 mask 255.255.0.0 10.0.1.1 metric 1 I have tried leaving out the gateway in the NIC1 and many other combinations with no success. Can anyone please help? What am I doing wrong?

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• Get Internal IP Address From DHCP Hostname

  - by ell

  I would like to try and get an internal ip address of one of the computers on my network. The reason for this is I have a little home server box downstairs but every time I want to SSH into it I have to open my router configuration and go on the DHCP client table and look at the IP address. For example I would like to be able to go ssh ell-sever instead of ssh 192.168.1.105 or whatever it happens to be. My network configuration is like so: Router downstairs that is connected to the Internet and is running a DHCP server My server computer (ell-server) is a headless pc connected to the router via ethernet cable. Running Ubuntu 11.04 Server Edition My laptop upstairs (ell-laptop) that is running Ubuntu 11.10 Desktop Edition connected wirelessly Other (irrelevant) computers - 2 x Windows XP, 1 x Xubuntu - all connected with cables. (It seemed to me the method of connection isn't useful information but I put it in anyway - just in case. If I have missed any information please tell me) Do I have to run a DNS server on one of my computers? If so which one? And does that mean I will have to run a DDNS client on each computer? Thanks in advance, ell.

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• Private IP getting routed over Internet

  - by WernerCD

  We are setting up an internal program, on an internal server that uses the private 172.30.x.x subnet... when we ping the address 172.30.138.2, it routes across the internet: C:\>tracert 172.30.138.2 Tracing route to 172.30.138.2 over a maximum of 30 hops 1 6 ms 1 ms 1 ms xxxx.xxxxxxxxxxxxxxx.org [192.168.28.1] 2 * * * Request timed out. 3 12 ms 13 ms 9 ms xxxxxxxxxxx.xxxxxx.xx.xxx.xxxxxxx.net [68.85.xx.xx] 4 15 ms 11 ms 55 ms te-7-3-ar01.salisbury.md.bad.comcast.net [68.87.xx.xx] 5 13 ms 14 ms 18 ms xe-11-0-3-0-ar04.capitolhghts.md.bad.comcast.net [68.85.xx.xx] 6 19 ms 18 ms 14 ms te-1-0-0-4-cr01.denver.co.ibone.comcast.net [68.86.xx.xx] 7 28 ms 30 ms 30 ms pos-4-12-0-0-cr01.atlanta.ga.ibone.comcast.net [68.86.xx.xx] 8 30 ms 43 ms 30 ms 68.86.xx.xx 9 30 ms 29 ms 31 ms 172.30.138.2 Trace complete. This has a number of us confused. If we had a VPN setup, it wouldn't show up as being routed across the internet. If it hit an internet server, Private IP's (such as 192.168) shouldn't get routed. What would let a private IP address get routed across servers? would the fact that it's all comcast mean that they have their routers setup wrong?

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• Two network interfaces and two IP addresses on the same subnet in Linux

  - by Scott Duckworth

  I recently ran into a situation where I needed two IP addresses on the same subnet assigned to one Linux host so that we could run two SSL/TLS sites. My first approach was to use IP aliasing, e.g. using eth0:0, eth0:1, etc, but our network admins have some fairly strict settings in place for security that squashed this idea: They use DHCP snooping and normally don't allow static IP addresses. Static addressing is accomplished by using static DHCP entries, so the same MAC address always gets the same IP assignment. This feature can be disabled per switchport if you ask and you have a reason for it (thankfully I have a good relationship with the network guys and this isn't hard to do). With the DHCP snooping disabled on the switchport, they had to put in a rule on the switch that said MAC address X is allowed to have IP address Y. Unfortunately this had the side effect of also saying that MAC address X is ONLY allowed to have IP address Y. IP aliasing required that MAC address X was assigned two IP addresses, so this didn't work. There may have been a way around these issues on the switch configuration, but in an attempt to preserve good relations with the network admins I tried to find another way. Having two network interfaces seemed like the next logical step. Thankfully this Linux system is a virtual machine, so I was able to easily add a second network interface (without rebooting, I might add - pretty cool). A few keystrokes later I had two network interfaces up and running and both pulled IP addresses from DHCP. But then the problem came in: the network admins could see (on the switch) the ARP entry for both interfaces, but only the first network interface that I brought up would respond to pings or any sort of TCP or UDP traffic. After lots of digging and poking, here's what I came up with. It seems to work, but it also seems to be a lot of work for something that seems like it should be simple. Any alternate ideas out there? Step 1: Enable ARP filtering on all interfaces: # sysctl -w net.ipv4.conf.all.arp_filter=1 # echo "net.ipv4.conf.all.arp_filter = 1" >> /etc/sysctl.conf From the file networking/ip-sysctl.txt in the Linux kernel docs: arp_filter - BOOLEAN 1 - Allows you to have multiple network interfaces on the same subnet, and have the ARPs for each interface be answered based on whether or not the kernel would route a packet from the ARP'd IP out that interface (therefore you must use source based routing for this to work). In other words it allows control of which cards (usually 1) will respond to an arp request. 0 - (default) The kernel can respond to arp requests with addresses from other interfaces. This may seem wrong but it usually makes sense, because it increases the chance of successful communication. IP addresses are owned by the complete host on Linux, not by particular interfaces. Only for more complex setups like load- balancing, does this behaviour cause problems. arp_filter for the interface will be enabled if at least one of conf/{all,interface}/arp_filter is set to TRUE, it will be disabled otherwise Step 2: Implement source-based routing I basically just followed directions from http://lartc.org/howto/lartc.rpdb.multiple-links.html, although that page was written with a different goal in mind (dealing with two ISPs). Assume that the subnet is 10.0.0.0/24, the gateway is 10.0.0.1, the IP address for eth0 is 10.0.0.100, and the IP address for eth1 is 10.0.0.101. Define two new routing tables named eth0 and eth1 in /etc/iproute2/rt_tables: ... top of file omitted ... 1 eth0 2 eth1 Define the routes for these two tables: # ip route add default via 10.0.0.1 table eth0 # ip route add default via 10.0.0.1 table eth1 # ip route add 10.0.0.0/24 dev eth0 src 10.0.0.100 table eth0 # ip route add 10.0.0.0/24 dev eth1 src 10.0.0.101 table eth1 Define the rules for when to use the new routing tables: # ip rule add from 10.0.0.100 table eth0 # ip rule add from 10.0.0.101 table eth1 The main routing table was already taken care of by DHCP (and it's not even clear that its strictly necessary in this case), but it basically equates to this: # ip route add default via 10.0.0.1 dev eth0 # ip route add 130.127.48.0/23 dev eth0 src 10.0.0.100 # ip route add 130.127.48.0/23 dev eth1 src 10.0.0.101 And voila! Everything seems to work just fine. Sending pings to both IP addresses works fine. Sending pings from this system to other systems and forcing the ping to use a specific interface works fine (ping -I eth0 10.0.0.1, ping -I eth1 10.0.0.1). And most importantly, all TCP and UDP traffic to/from either IP address works as expected. So again, my question is: is there a better way to do this? This seems like a lot of work for a seemingly simple problem.

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• How can I change the location of my ip address to Orlando, FL from other city where I live and using forum/chat-room? [on hold]

  - by MSEUCF

  I live in West Palm Beach, Florida. However, I am attending to school at University of Center Florida for materials science and engineering. Right now, I am on vacation and live in WPB, FL. There is one certainly problem when I login at private forum I'm getting error for not same the ip-address so I had to make new account with false information in city and still unable to success. Of course, it won't do that due to policy from forum required the ip-address has to be same in Orlando, FL. local only. How can I change the location of my ip address to Orlando? Also, in chat-room from forum it would show my ip-address so I'd be in trouble if they find out that I am not live in Orlando. Please help with me. Tell me how to change ip adress step and step. Thank you. *I use AT&T and Belkin Router Wifi. Forgiven me for my English is not very well. ESL. I am a foreign student.

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• Resolving a Forward Declaration Issue Involving a State Machine in C++

  - by hypersonicninja

  I've recently returned to C++ development after a hiatus, and have a question regarding implementation of the State Design Pattern. I'm using the vanilla pattern, exactly as per the GoF book. My problem is that the state machine itself is based on some hardware used as part of an embedded system - so the design is fixed and can't be changed. This results in a circular dependency between two of the states (in particular), and I'm trying to resolve this. Here's the simplified code (note that I tried to resolve this by using headers as usual but still had problems - I've omitted them in this code snippet): #include <iostream> #include <memory> using namespace std; class Context { public: friend class State; Context() { } private: State* m_state; }; class State { public: State() { } virtual void Trigger1() = 0; virtual void Trigger2() = 0; }; class LLT : public State { public: LLT() { } void Trigger1() { new DH(); } void Trigger2() { new DL(); } }; class ALL : public State { public: ALL() { } void Trigger1() { new LLT(); } void Trigger2() { new DH(); } }; // DL needs to 'know' about DH. class DL : public State { public: DL() { } void Trigger1() { new ALL(); } void Trigger2() { new DH(); } }; class HLT : public State { public: HLT() { } void Trigger1() { new DH(); } void Trigger2() { new DL(); } }; class AHL : public State { public: AHL() { } void Trigger1() { new DH(); } void Trigger2() { new HLT(); } }; // DH needs to 'know' about DL. class DH : public State { public: DH () { } void Trigger1() { new AHL(); } void Trigger2() { new DL(); } }; int main() { auto_ptr<LLT> llt (new LLT); auto_ptr<ALL> all (new ALL); auto_ptr<DL> dl (new DL); auto_ptr<HLT> hlt (new HLT); auto_ptr<AHL> ahl (new AHL); auto_ptr<DH> dh (new DH); return 0; } The problem is basically that in the State Pattern, state transitions are made by invoking the the ChangeState method in the Context class, which invokes the constructor of the next state. Because of the circular dependency, I can't invoke the constructor because it's not possible to pre-define both of the constructors of the 'problem' states. I had a look at this article, and the template method which seemed to be the ideal solution - but it doesn't compile and my knowledge of templates is a rather limited... The other idea I had is to try and introduce a Helper class to the subclassed states, via multiple inheritance, to see if it's possible to specify the base class's constructor and have a reference to the state subclasse's constructor. But I think that was rather ambitious... Finally, would a direct implmentation of the Factory Method Design Pattern be the best way to resolve the entire problem?

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• [plesk]Warning: None of IP addresses specified in A DNS records match the IP address used for hostin

  - by Saif Bechan

  Hi, anyone know what this warning means in plesk. The ip i use is from my server, and i can assign domains to it?. Why does this error pop up? This errors comes up when i add A records for my domain.

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• Configuring Cisco ASA 5510 to assign static IP address based on MAC address

  - by knd

  Hi, We have a CISCO ASA 5510 at work. We want to configure the same such that it can serve specific IP addresses based on the MAC address of the clients. Any help would be greatly appreciated. Thanks in advance -knd

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• Calculating and billing IP multicast usage on the Internet

  - by obvio171

  I've been searching for the reasons why IP multicast isn't widely supported on the Public Internet, and a commonly-cited reason is the difficulty ISPs have in tracking Multicast usage for later billing. Given this difficulty, since ISPs control the routers and they're not forced to support Multicast (as per IPv4), they just disable it. I couldn't find what this difficulty was though. Since an ISP has full control of any inbound and outbound traffic, be it Unicast or Multicast, what's the difficulty in tracking and billing the latter that does not exist in the former?

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