LinuxQuestions.org - Automatic connection to different hotspots

You might want to check out KwifiManager, which does some of what you want. It can store up to four different configurations and despite the K moniker, it runs on pretty much any X desktop. However, it might require a KDE library or two. However, I don't think it scans for new networks.

I got tired of pretty much the same problem, so I wrote a script that stores the info for my home network, but before it configures the card it first scans for available networks and then presents a list to choose from. Since my home network is the only one I use WEP for, it doesn't store keys for other networks, but it wouldn't be hard to modify it to do so. Since I use ndiswrapper, it loads that module, but that would be easy to change to load different modules. It is also written for Slackware, so it may need some tweaking to work with other distros.

Code:

#!/usr/bin/perl

$Interface = "wlan0";

$HomeESSID = "HomeDomainName";

$WEP = "HomeWEPKey";

$Mode = "Managed";

$IWCONFIG = "/sbin/iwconfig";

$DHCP = "/sbin/dhcpcd -t 10 -d";

@APList = ();

#First load the ndiswrapper module

print("Loading ndiswrapper\n");

system("/sbin/modprobe ndiswrapper");

print("Scanning for wireless access points\n");

@ScanList = qx/iwlist wlan0 scan/;

foreach $a (@ScanList){

 if($a =~m/No scan results/){

                print("No networks detected, enabling home network\n");

                &homeNet;

        }

 if($a =~ m/$HomeESSID/){

                print("Home network detected\n");

  &homeNet;

 }

 if ($a =~m/ESSID/){

  @Temp = split(/"/,$a);

  push(@APList,$Temp[1]);

  for($x=0;$x<=$#APList;$x++){

  print("At $x is $APList[$x]\n");

  }

 }

}

&selectFrom;

sub homeNet{

 print("Setting up wlan0\n");

 system("$IWCONFIG $Interface essid $HomeESSID");

 system("$IWCONFIG $Interface mode $Mode");

        #&errorCheck('Second Mode');

        system('/sbin/iwconfig wlan0 key $WEP);

        #&errorCheck('WEP');

        print("Requesting IP from $HomeESSID\n");

        system("$DHCP $Interface");

        #&errorCheck('DHCPCD');

        system ("ifconfig $Interface up");

        #&errorCheck('Ifup');

        print("Configuration done\n");

        exit;

}

sub selectFrom{

        print("Select one of the following AP points\n");

        for($x=0;$x<=$#APList;$x++){

                print("$x - $APList[$x]\n");

        }

        print("Select by number: ");

        $SelectAP = <STDIN>;

        if((0 <= $SelectAP) and ($SelectAP<=$#APList)){

                print("Using $APList[$SelectAP]\n");

                system("$IWCONFIG $Interface essid $APList[$SelectAP]");

                print("Requesting IP from $APList[$SelectAP]");

                system("$DHCP $Interface");

                system("ifconfig $Interface up");

                exit;

        }

        else{

                print("Please select an acceptable number\n");

                &selectFrom;

        }

        exit;

}