Is it IPv6 Time ? IPv6 Basics on Linux

The first time I worked on IPv6 was in 2000 in my master’s degree thesis where I started an implementation of Mobile IP based on IPv6 in Linux Redhat. Over a decade later, IPv6 has not really taken off, even though we hear stories about the IPv4 address space running out and I have yet to see an embedded device using anything else than IPv4. APNIC Ran out of IPv4 However, this may be about the change as on the 15th of April 2011, Japan Network Information Center (JPNIC) announced that APNIC (Asia Pacific Network Information Centre) ran out of IPv4 addresses. They will still try to make it last longer by reusing previously allocated IPv4 and an “IPv4 address transfer system” whose details will be made available later. You can also see a chart based on IANA (Internet Assigned Numbers Authority) data that shows this is a problem right now. If we have to update all devices to support …

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Finding a device IP Address

If you are developing software for an Ethernet (or Wifi) device, you’ll need to access the board for debugging and/or testing purpose. If your board does not have user interface or the serial port is not available, you’ll have to find the IP address (assuming it is using DHCP) before accessing the board thru telnet or ssh. A simple way to do that is to ping the broadcast address and check the arp table. > ping -b 192.168.0.255 WARNING: pinging broadcast address PING 192.168.0.255 (192.168.0.255) 56(84) bytes of data. 64 bytes from 192.168.0.246: icmp_seq=0 ttl=64 time=0.018 ms 64 bytes from 192.168.0.101: icmp_seq=0 ttl=64 time=0.217 ms (DUP!) 64 bytes from 192.168.0.246: icmp_seq=1 ttl=64 time=0.023 ms > arp -i eth0 arp -i eth1 Address                  HWtype  HWaddress           Flags Mask            Iface 192.168.0.103            ether   00:50:FC:00:00:01   C                     eth1 192.168.0.109            ether   00:13:20:01:01:01   C                     eth1 If you cannot find your device, it may be configured to ignore ping broadcast (in order to avoid denial-of-service attack). To …

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Linux LAN Port Scanner

Just a short post to show how to scan the open ports of a remote machine on the local network: sudo nmap -sS 10.10.10.123 Starting nmap 3.81 ( http://www.insecure.org/nmap/ ) at 2010-04-28 16:00 HKT Interesting ports on 10.10.10.123: (The 1660 ports scanned but not shown below are in state: filtered) PORT    STATE  SERVICE 69/tcp  closed tftp 139/tcp open   netbios-ssn 445/tcp open   microsoft-ds MAC Address: 00:50:FC:B1:E9:70 (Edimax Technology CO.) Nmap finished: 1 IP address (1 host up) scanned in 25.252 seconds Support CNX Software – Donate via PayPal or become a Patron on Patreon

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