From Forum Nokia Wiki

For symbian 7.0s

step:1 from startup programs select series60sdk->tools->ethernetconf In ethernet confg--->mark check for option network in promiscious mode. give separate/free static ip for emulator. fill the gateway and dns as per your LAN settings.....

step:2 start c:\sym\series60_v21\epoc32\tools\npacketadmin.exe.

step:3 now,run your emulator and from services you could now connect to any web site.. You can check its send/receive packets from npacketadmin.exe (which is already running).

For Symbian 8.0a

start with step 2:

step 3: run emulator and set ethernet conf from tools->preferences in emulator.