#wlan0

import socket import fcntl import struct def get_ip_address(ifname):    s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)    return socket.inet_ntoa(fcntl.ioctl(        s.fileno(),        0x8915,  # SIOCGIFADDR        struct.pack('256s', ifname[:15])    )[20:24]) print get_ip_address('lo') print get_ip_address('eth0’)

Great to be back...was busy learning and trying cross compiling. While using Raspberry Pi for the past week, I discover that MTU size may have an impact in the network stability, especially I use Raspberry Pi solely via SSH.

An example, I press and hold any keyboard key, say 's'. The string of commands is being sent to Raspberry Pi via SSH. There will be intermediate pauses while doing so, as if the Raspberry Pi is trying to grasp for air. After, I reduce the MTU size (default is 1500), the pauses become less and response on the terminal console seem smoother.

Für ein kleines projekt habe ich mal angefangen mich mit dem Routen von Paketen auseinander zu setzten. Dies ist dabei herrausgekommen:

Routing Script (/usr/sbin/router): 

#!/bin/bash PATH=/usr/sbin:/sbin:/bin:/usr/bin # # delete all existing rules. # iptables -F iptables -t nat -F iptables -t mangle -F iptables -X # Always accept loopback traffic iptables -A INPUT -i lo -j ACCEPT

# Allow established connections, and those not coming from the outside iptables -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT iptables -A INPUT -m state --state NEW -i wlan0 -j ACCEPT iptables -A FORWARD -i eth0 -o wlan0 -m state --state \                                    ESTABLISHED,RELATED -j ACCEPT # Allow outgoing connections from the LAN side. iptables -A FORWARD -i wlan0 -o eth0 -j ACCEPT # Masquerade. iptables -t nat -A POSTROUTING -o wlan0 -j MASQUERADE # Enable routing. echo 1 > /proc/sys/net/ipv4/ip_forward route add -net 192.168.2.0 netmask 255.255.255.0 dev eth0

Netzwerk Interfaces (/etc/network/interfaces):

#loopback device auto lo iface lo inet loopback #iface eth0 inet dhcp iface eth0 inet static         address 192.168.2.1         netmask 255.255.255.0         network 192.168.2.0         broadcast 192.168.2.255

DHCPD Konfiguration (/etc/udhcpd.conf):

start           192.168.2.20    #default: 192.168.0.20 end             192.168.2.254   #default: 192.168.0.254 interface       eth0            #default: eth0 opt     dns     192.168.1.1 option  subnet  255.255.255.0 opt     router  192.168.2.1 opt     wins    192.168.1.1 option  domain  local option  lease   864000          # 10 days of seconds

So, nur noch 

sudo router sudo service udhcpd start