This is a simple bash script to check whether NIC is dropping packets or not. It works with only one NIC card at one time because there’s possiblity that packet can go through another NIC. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 [...]

If you travel frequently and have to access wireless internet in that country, you’d be better to check this article. Sometimes, in foreign country, you would face with unaccessible wireless AP. One of the possible reason is that you use the different country code which is described in IEEE 802.11 regulatory domain code? from the [...]

You can find the file named /proc/sys/net/ipv4/tcp_max_tw_buckets. In the kernel-doc, it explained something like following messages. tcp_max_tw_buckets – INTEGER Maximal number of timewait sockets held by system simultaneously. If this number is exceeded time-wait socket is immediately destroyed and warning is printed. This limit exists only to prevent simple DoS attacks, you _must_ not lower [...]

Have you ever seen any problem with ARP table caching? What will happen if node A have two NIC with same IP. At first, just one of them is active and got a IP. If something is going wrong, the second NIC become active and request the same IP and node operate without hanging. This [...]