DigitalOcean perhaps iptables or your kernel needs to be upgraded

我的 ubnutn 是 14.04，本來今天要看一下怎麼設定防火牆，今天在下 iptables -L  時出現 『Perhaps iptables or your kernel needs to be upgraded.』 這個訊息，真是嚇死我了...

root@demo-server:~# iptables -L
modprobe: ERROR: ../libkmod/libkmod.c:556 kmod_search_moddep() could not open moddep file '/lib/modules/3.13.0-36-generic/modules.dep.bin'
iptables v1.4.21: can't initialize iptables table `filter': Table does not exist (do you need to insmod?)
Perhaps iptables or your kernel needs to be upgraded.

後來根據官方的討論論壇，解藥:

apt-get install linux-image-$(uname -r)

再重新下 iptables -L 就可以了。
(下 iptables 需要 root 權限，sudo iptables -L，範例沒有是因為我已經是用 root 登入)


參考
＊ problem with iptables and ubuntu Ubuntu 13.10
＊ How To Set Up a Firewall Using IP Tables on Ubuntu 12.04
＊ 配置Ubuntu後透過SSH連線設定Host以及防火牆
＊ 佛祖球球-[Ubuntu]iptables 設定