cryptmount で swap を作ってみた

cryptmount で swap を作ってみた

$ sudo install /dev/null -m 600 /var/swapfile
$ sudo dd if=/dev/zero of=/var/swapfile bs=1M count=1024
1024+0 レコード入力
1024+0 レコード出力
1073741824 bytes (1.1 GB, 1.0 GiB) copied, 9.51219 s, 113 MB/s
$ sudo vi /etc/cryptmount/cmtab
$ cat /etc/cryptmount/cmtab
# /etc/cryptmount/cmtab - encrypted filesystem information for cryptmount
# try 'man 8 cryptmount' or 'man 5 cmtab' for more details
swapfile {
dev=/var/swapfile
fstype=swap
flags=mkswap
cipher=twofish
keyfile=/dev/random keymaxlen=32 keyformat=raw
}
$ cat /proc/swaps
Filename Type Size Used Priority
/dev/dm-3 partition 8277500 255916 -2
$ sudo /usr/bin/cryptmount --swapon swapfile
$ cat /proc/swaps
Filename Type Size Used Priority
/dev/dm-3 partition 8277500 17920 -2
/dev/mapper/swapfile partition 1048572 0 256
$ sudo cryptmount --swapoff swapfile
$ cat /proc/swaps
Filename Type Size Used Priority
/dev/dm-3 partition 8277500 17376 -2


しかし，2回目は失敗する?ddし直したらいけるんだけども……．
$ sudo cryptmount --swapon swapfile
Device "/var/swapfile" appears to contain data (entropy=0.0677,4.09) - please run mkswap manually