Knowledge Base : NAT clients have problem accessing certain site

Sarah_Radzi

Configuration :
Private LAN connecting to Internet through Internet Connection Sharing (ICS).

OS : ALL

Symptoms :
NAT clients behind the Internet Gateway (PC running ICS) have problems connecting to certain sites via HTTP, FTP, POP3, SSH, TELNET, etc ..
Connection is established but the client failed to receive data from the server.

Diagnostic :

Windows > try ping -f -l 1500 xxx.xxx.xxx.xxx with xxx.xxx.xxx.xxx is your gateway and then an internet address which is having problems. If it does not work, reduce 1500 to a smaller value again and again until  it works ! (try 1500,1492,1454, ...)

Linux (or equiv) > try ping -s 1500 xxx.xxx.xxx.xxx and follow the same procedure as windows

Cause :
The MTU setting on the client is too high

How to solve :
Reduce the MTU for the interface.
Linux : ifconfig interface mtu |i]mtu_value
Windows : Regedit > HKLM/System/CurrentControlSet/Service/Tcpip/Parameters/Interfaces
find the right interface and add a DWORD MTU with the value found via ping (ATTN : decimals ! not hexa !)

Sarah_Radzi

cilakak punya MTU, penat cari satu minggu apsal takleh access sesetengah website ! nf:

Sarah_Radzi

mod .. tolong digest dan move  ke board programming and networking ..

ps: digest dulu lah .. kalau dah move takleh modify ;)

Remy_3D

mcm nie yang punca segala masalah kat network i. Kena check esok pagi nie.....

Remy_3D

tapi i tak pakai ICS......

Sarah_Radzi

MTU problem tak perlu ICS ..

bila pakai ICS .. server ok sbb mtu dia modem yang set .. jadi cuma client je bermasalah ..

Remy_3D

problem i masa nie sarah, ftp, mirc, msn tak working. every 2 mins dier dc sendiri.