Connect to OpenWrt’s background terminal with SSH

1. Download and open PuTTY under Windows. Fill in the address of your router in the “Host Name” field (in my case 192.168.2.1). Enter 22 in “Port” field. Choose SSH as “Connection Type”. Click “Save” for future use, and click open. (You should modify your password in the administration interface / web interface before this step.)
2. Login as root, hit enter, input password and hit enter, and now you are at the background console!

Mounting (thumb / hard-) drives on USB port

1. First read closely to the “Attitude Adjustment” part in these articles:
   http://wiki.openwrt.org/doc/howto/usb.storage
   http://wiki.openwrt.org/doc/howto/usb.essentials
2. Install the packages you need according to these articles. Here’s an example:
   opkg update
opkg install kmod-usb-core kmod-usb2 kmod-fs-ext4 kmod-usb-storage
3. Format the thumb drive. Mine is a Verbatim Store N Go 4G. I use Acronis Disk Director in Windows to create two partitions. The second one is of size 256MB at the end of the disk. Format it as Linux Swap partition. Create another partition in the free space before the second one, and format it as ext* partitions. I use ext2.
4. SSH to console of OpenWrt, cd /mnt/, and ls; you should now see your automounted sda1 partition. If not, you can manually mount it by entering:
   mkdir -p /mnt/sda1
mount -t ext2 /dev/sda1 /mnt/sda1 -o rw,sync
   Then ls /mnt/sda1 again, and see if you can see your files in the thumb disk. By default there should be a directory / folder called lost+found. You can also mkdir a directory in the thumb disk, plug it on to your computer, and use DiskGenius to check if the directory you just created exists.
5. Creating Swap partitions in Windows can cause mysterious issues, so in the console of OpenWrt, execute: (Confirm that sda2 is the small 256MB partition on your thumb disk before this!)
   mkswap /dev/sda2
   to re-establish the Swap partition

Swap

Execute swapon /dev/sda2 and then freeto see if the volume beside Swap is non-zero. If it is non-zero then you succeeds.

extroot & autoswap

1. Read closely to the “Attitude Adjustment” part in
   http://wiki.openwrt.org/doc/howto/extroot
   to confirm you do need extroot.
2. Install packages you need. For instance,
   opkg update
opkg install block-mount
3. Confirm that your first large partition of the thumb disk is mount to /mnt/sda1 Copy ROM to the drive; here I use pivot root by executing:
   mkdir -p /tmp/cproot
mount --bind / /tmp/cproot
tar -C /tmp/cproot -cvf - . | tar -C /mnt/sda1 -xf -
umount /tmp/cproot
rmdir /tmp/cproot
4. The most KEY step: configuring fstab file! It is located at /etc/config/fstab There are two versions of this file, one in the internal ROM / internal storage, and the other just copied into the thumb drive. Since we haven’t extrooted yet, if we visit the path above, you are accessing the fstab file in ROM. I’ll let the fstab file in ROM to deal with extroot only, so in my case, its content is as the following:
   config global automount
option from_fstab 0
option anon_mount 1
config global autoswap
option from_fstab 0
option anon_swap 0
config mount
option target /
option device /dev/sda1
option fstype ext2
option options rw,sync
option enabled 1
option enabled_fsck 0
   You can use vi to change the file. If you are not used to it, you can download the file, edit it, and upload it using WinSCP.
5. Then run reboot After it reboots, SSH to console again, run df and see if volume of the root directory / is correct (it should be the volume of the first partition on your thumb disk. If it is correct, you have successfully extrooted
6. Now visiting /etc/config/fstab you visit the file in the thumb drive, so it appears that you haven’t change the file. I use the fstab file in the thumb drive to autoswap, because it appears to me that the fstab file in ROM is loaded first, mounting /dev/sda1 to code> / according to config mount and then load the fstab file in the thum disk. Again, (after you successfully extrooted) run vi /etc/config/fstab and edit the file to be as the following:
   config global automount
option from_fstab 0
option anon_mount 1
config global autoswap
option from_fstab 1
option anon_swap 0
config swap
option device /dev/sda2
option enabled 1
7. Then reboot, and confirm autoswap by executing free

BTW, refer to the following if you want to change the parameters in “global automount” and “global autoswap” in fstab:http://wiki.openwrt.org/doc/uci/fstab. For the usage of vi, refer tohttp://www.gentoo.org/doc/zh_cn/vi-guide.xml.

SSH到OpenWrt的后方控制台

1. 下载打开PuTTY，在Host Name中填入路由器地址（我这里是192.168.2.1），Port为22，选中SSH，点一下下面的Save保存方便以后使用，然后Open。（这一步的前提是在路由器管理界面那里设置了密码。）
2. login as输入root，回车，输入密码回车，就能来到OpenWrt的控制台了！

挂载U盘

1. 首先仔细阅读下面这些文章中的Attitude Adjustment部分
   http://wiki.openwrt.org/doc/howto/usb.storage
   http://wiki.openwrt.org/doc/howto/usb.essentials
2. 按照上面的方法，安装需要的包。这里给一个例子：
   opkg update
opkg install kmod-usb-core kmod-usb2 kmod-fs-ext4 kmod-usb-storage
3. 格式化U盘。把U盘插在电脑上，我的是Verbatim Store N Go 4G，在Windows下使用Acronis Disk Director重新分为两个分区，第二个分区在磁盘末尾，256MB，Linux Swap格式，前面剩下的分出第一个分区，我使用的是ext2格式。
4. SSH到OpenWrt后台，cd进/mnt/目录，ls一下，应该就看到自动挂载的sda1分区了，如果没有，手动挂载一个：
   mkdir -p /mnt/sda1
mount -t ext2 /dev/sda1 /mnt/sda1 -o rw,sync
   然后再次 ls /mnt/sda1 看看是否能显示U盘的文件。默认应该有一个lost+found的文件夹。也可以手动mkdir一个文件夹然后拔下来放到电脑里用Disk Genius看看文件夹是否存在来确认第一个分区是否加载成功。
5. 在Windows下创建的Swap分区总有这样那样的问题，所以执行（执行前先确认sda2的确为U盘第二个256MB的小分区！）
   mkswap /dev/sda2
   来重新建立Swap分区。

Swap

执行swapon /dev/sda2后，执行free命令，观察Swap旁边的容量值是不是非零，如果非零则成功。

extroot & autoswap

1. 首先仔细阅读下面这些文章中的Attitude Adjustment部分
   http://wiki.openwrt.org/doc/howto/extroot
   来确认你的确需要extroot这种东西
2. 安装需要的包。比如：
   opkg update
opkg install block-mount
3. 确认U盘第一个大分区已经挂载到/mnt/sda1。复制Rom文件到U盘。这里使用pivot root的方法。执行：
   mkdir -p /tmp/cproot
mount --bind / /tmp/cproot
tar -C /tmp/cproot -cvf - . | tar -C /mnt/sda1 -xf -
umount /tmp/cproot
rmdir /tmp/cproot
4. 最关键的一步来了！配置fstab文件。它的路径是/etc/config/fstab。这个文件分两个，一个是Rom中的，一个是刚刚复制到U盘中的。现在由于还没有进行extroot，访问上面这个路径会访问到Rom中的fstab。我让Rom中的fstab文件只管extroot，所以它的内容是：
   config global automount
option from_fstab 0
option anon_mount 1
config global autoswap
option from_fstab 0
option anon_swap 0
config mount
option target /
option device /dev/sda1
option fstype ext2
option options rw,sync
option enabled 1
option enabled_fsck 0
   使用vi来修改这个文件，如果不习惯vi，则用WinSCP下载这个文件然后修改然后上传到路由器。
5. 然后执行reboot命令，重启路由器后重新SSH到路由器，执行df命令，看看根目录 / 的容量是否正确（即为U盘第一分区的容量）。如果正确就成功extroot了。
6. 现在访问/etc/config/fstab会访问到U盘中的fstab文件，所以会看到修改前的样子。我使用U盘中的fstab文件来autoswap，因为据我观察似乎是先加载Rom中的fstab文件，根据config mount段把/dev/sda1加载到 / ，然后这时候就会再访问U盘上的fstab文件。这时（成功extroot后）重新vi /etc/config/fstab，更改这个文件为以下内容：
   config global automount
option from_fstab 0
option anon_mount 1
config global autoswap
option from_fstab 1
option anon_swap 0
config swap
option device /dev/sda2
option enabled 1
7. 重启，通过free命令确认autoswap是否成功。

另外，fstab中的global automount和global autoswap的各项参数可以参考：http://wiki.openwrt.org/doc/uci/fstab。关于vi的使用可以看看这些链接：http://www.gentoo.org/doc/zh_cn/vi-guide.xml。