Xu Shijie's questions

I am asking how to change uuid in /boot/grub/grub.cfg, so that grub can load OS on a specified partition.

I have two disks:

• SSD /dev/sda1 with uuid d7f0cf11-3edf-4859-b65a-3b5bc60ea7b9
• HDD /dev/sdb1 with uuid 47d9205b-00a8-40e5-88d6-e8b9571799a7

Both disks contain the same content (a Ubuntu root) but different partition uuids, as content of sda1 is cloned from sdb1 by clonezilla

The problem is /boot/grub/grub.cfg, which is automatically generated, contains:

           if [ x$feature_platform_search_hint = xy ]; then
              search --no-floppy --fs-uuid --set=root --hint-bios=hd1,msdos1 --hint-efi=hd1,msdos1 --hint-baremetal=ahci1,msdos1  47d9205b-00a8-40e5-88d6-e8b9571799a7
            else
              search --no-floppy --fs-uuid --set=root 47d9205b-00a8-40e5-88d6-e8b9571799a7
            fi
            echo    'Loading Linux 4.4.0-146-generic ...'
            linux   /boot/vmlinuz-4.4.0-146-generic root=UUID=47d9205b-00a8-40e5-88d6-e8b9571799a7 ro  quiet splash $vt_handoff

indicating that grub chooses Ubuntu root from sdb1 instead of sda1, while i want it to choose sda1.

I tried replace all 47d9205b-00a8-40e5-88d6-e8b9571799a7 by d7f0cf11-3edf-4859-b65a-3b5bc60ea7b9 directly, and then run update-grub, but then everything is reverted back.

So is there any other better solution? the /boot/grub/grub.cfg is actually generated automatically. If I detached the sdb1, grub was unable to launched, as it could not find the uuid of sdb1.

Thanks

Updates:

shijiex@shijie:~$ cat /etc/fstab
# /etc/fstab: static file system information.
#
# Use 'blkid' to print the universally unique identifier for a
# device; this may be used with UUID= as a more robust way to name devices
# that works even if disks are added and removed. See fstab(5).
#
# <file system> <mount point>   <type>  <options>       <dump>  <pass>
proc            /proc           proc    nodev,noexec,nosuid 0       0
# / was on /dev/sda1 during installation
UUID=d7f0cf11-3edf-4859-b65a-3b5bc60ea7b9  /               ext4    errors=remount-ro 0       1

#UUID=47d9205b-00a8-40e5-88d6-e8b9571799a7 /old_os               ext4    errors=remount-ro 0       2
# /backup was on /dev/sda5 during installation
UUID=d36e69de-3af8-4302-a2b1-f32c2538493d /backup         ext4    defaults        0       0
# /home was on /dev/sda7 during installation
UUID=95ffe5be-ed1c-4d2b-b745-e31ba62ca63d /home           ext4    defaults        0       2
#UUID=e2ae897d-62b1-45d3-a17a-49e7a1b8fbe7 /home           ext4    defaults        0       2

# /vm was on /dev/sda8 during installation
#UUID=222bf555-b2d3-4607-a856-f5fd785b1862  /vm            ext4    defaults        0       2
# /opt was on /dev/sda8 during installation
UUID=ffbc1ea0-f426-4def-9349-a6f68b486b2f  /opt       ext4    defaults        0       0
# /other was on /dev/sda6 during installation
UUID=657778bc-fde8-4261-9fe6-4134c6a7fb3f /other          ext4    defaults        0       0


# /other was on /dev/sda6 during installation
#UUID=6db98036-2350-4289-b9ef-8e0a2ae52eeb /win           ext4    defaults        0       2


# swap was on /dev/sda9 during installation
UUID=71c498b2-3484-4d5b-b64a-270cc352841b  none            swap    sw              0       0
#UUID=05f1ba29-4188-40d1-8597-de708b48ed50  /tmp           swap    sw              0       0

and blkid:

 shijiex@shijie:~$ sudo blkid 

[sudo] password for shijiex: 
/dev/sda1: UUID="d7f0cf11-3edf-4859-b65a-3b5bc60ea7b9" TYPE="ext4" PARTUUID="2fe05ff9-01"
/dev/sda3: UUID="95ffe5be-ed1c-4d2b-b745-e31ba62ca63d" TYPE="ext4" PARTUUID="2fe05ff9-03"
/dev/sda4: UUID="8d114eed-5ce4-4d6f-8a28-8a7092b01d46" TYPE="ext4" PARTUUID="2fe05ff9-04"
/dev/sda5: UUID="94b0fb65-f56d-426d-81f9-d05a8ac783eb" TYPE="ext4" PARTUUID="2fe05ff9-05"
/dev/sdb1: UUID="47d9205b-00a8-40e5-88d6-e8b9571799a7" TYPE="ext4" PARTUUID="0001c588-01"
/dev/sdb10: LABEL="New Volume" UUID="6db98036-2350-4289-b9ef-8e0a2ae52eeb" TYPE="ext4" PARTUUID="0001c588-0a"
/dev/sdb11: UUID="ffbc1ea0-f426-4def-9349-a6f68b486b2f" TYPE="ext4" PARTUUID="0001c588-0b"
/dev/sdb5: UUID="d36e69de-3af8-4302-a2b1-f32c2538493d" TYPE="ext4" PARTUUID="0001c588-05"
/dev/sdb6: UUID="657778bc-fde8-4261-9fe6-4134c6a7fb3f" TYPE="ext4" PARTUUID="0001c588-06"
/dev/sdb7: UUID="e2ae897d-62b1-45d3-a17a-49e7a1b8fbe7" TYPE="ext4" PARTUUID="0001c588-07"
/dev/sdb8: UUID="222bf555-b2d3-4607-a856-f5fd785b1862" TYPE="ext4" PARTUUID="0001c588-08"
/dev/sdb9: UUID="71c498b2-3484-4d5b-b64a-270cc352841b" TYPE="swap" PARTUUID="0001c588-09"
/dev/loop0: TYPE="squashfs"
/dev/loop1: TYPE="squashfs"
/dev/loop2: TYPE="squashfs"
/dev/loop3: TYPE="squashfs"
/dev/loop4: TYPE="squashfs"

I installed Sougou chinese pinying input long time ago, and it keeps working for a long time (more than years). Recently, it suddenly encounters a problem and I could not get any Chinese Characters any more.

When the system is on Sougou status, I tried to type something, and takes the picture using my phone（The first picture ）. When click space, it only results in Shuju instead of Chinese Characters.

I also show another two screenshots when it is in and .

My system is Ubuntu 1404. Anyone has similar issues and solutions? Thanks

After installation openvpn and dnsmasq, I found the web browsing is very slow. I tried to configure the server.conf, and then use http://speedof.me/ to test. Here is the result:

 Download   Upload
   34         15       NO VPN
   13         17
   1.06       890k     VPN-    no comp-lzo
   900k       1.08m  VPN -   comp-lzo
   1.04      530 
   370        1.24     
   610      910    nocomp_lzo + sndbuf 393216  + rcvbuf 393216
    630       870  
    0.99    860
    790   790
     870   1.07       sendbuf+recebuf   mtu mssfix   with different buf size.
     1.11  1.13
     1     1.18
     1.09    970
     250     360        mtu+mssfix with different value
     260     540 
     1.06    860
     1.07    900  

Both server and client are Ubuntu 1404. From the table, the performance is degraded significantly. Without VPN, the download can easily go to 15M, while it becomes 1M or less after connection.

sendbuf and recebuf

I do not think this is issue, since the fix for it has been included in 2.3.9 (change discussion and Change commit), while the VPN version on my side are both 2.3.10.

I tried some values and push both to client (Sample configuration), but little performance is improved.

MTU+mssfix+fragment :

I tried many combinations for these three values (6000, 0, 0), (6000, 0, 1440), (48000, 0, 0), and change the cipher method accordingly. But still little helps (Tunning).

Since it is too slow, and experience of web browser is very BAD. Does anyone have a good suggestion, or optimized configuration values, or suggestion? Thanks in advance.

My current server.conf

#################################################
# Sample OpenVPN 2.0 config file for            #
# multi-client server.                          #
#                                               #
# This file is for the server side              #
# of a many-clients <-> one-server              #
# OpenVPN configuration.                        #
#                                               #
# OpenVPN also supports                         #
# single-machine <-> single-machine             #
# configurations (See the Examples page         #
# on the web site for more info).               #
#                                               #
# This config should work on Windows            #
# or Linux/BSD systems.  Remember on            #
# Windows to quote pathnames and use            #
# double backslashes, e.g.:                     #
# "C:\\Program Files\\OpenVPN\\config\\foo.key" #
#                                               #
# Comments are preceded with '#' or ';'         #
#################################################

# Which local IP address should OpenVPN
# listen on? (optional)
;local a.b.c.d

# Which TCP/UDP port should OpenVPN listen on?
# If you want to run multiple OpenVPN instances
# on the same machine, use a different port
# number for each one.  You will need to
# open up this port on your firewall.
port 1194

# TCP or UDP server?
;proto tcp
proto udp

# "dev tun" will create a routed IP tunnel,
# "dev tap" will create an ethernet tunnel.
# Use "dev tap0" if you are ethernet bridging
# and have precreated a tap0 virtual interface
# and bridged it with your ethernet interface.
# If you want to control access policies
# over the VPN, you must create firewall
# rules for the the TUN/TAP interface.
# On non-Windows systems, you can give
# an explicit unit number, such as tun0.
# On Windows, use "dev-node" for this.
# On most systems, the VPN will not function
# unless you partially or fully disable
# the firewall for the TUN/TAP interface.
;dev tap
dev tun

# Windows needs the TAP-Win32 adapter name
# from the Network Connections panel if you
# have more than one.  On XP SP2 or higher,
# you may need to selectively disable the
# Windows firewall for the TAP adapter.
# Non-Windows systems usually don't need this.
;dev-node MyTap

# SSL/TLS root certificate (ca), certificate
# (cert), and private key (key).  Each client
# and the server must have their own cert and
# key file.  The server and all clients will
# use the same ca file.
#
# See the "easy-rsa" directory for a series
# of scripts for generating RSA certificates
# and private keys.  Remember to use
# a unique Common Name for the server
# and each of the client certificates.
#
# Any X509 key management system can be used.
# OpenVPN can also use a PKCS #12 formatted key file
# (see "pkcs12" directive in man page).
ca ca.crt
cert server.crt
key server.key  # This file should be kept secret

# Diffie hellman parameters.
# Generate your own with:
#   openssl dhparam -out dh2048.pem 2048
dh dh2048.pem

# Network topology
# Should be subnet (addressing via IP)
# unless Windows clients v2.0.9 and lower have to
# be supported (then net30, i.e. a /30 per client)
# Defaults to net30 (not recommended)
;topology subnet

# Configure server mode and supply a VPN subnet
# for OpenVPN to draw client addresses from.
# The server will take 10.8.0.1 for itself,
# the rest will be made available to clients.
# Each client will be able to reach the server
# on 10.8.0.1. Comment this line out if you are
# ethernet bridging. See the man page for more info.
server 10.8.0.0 255.255.255.0

# Maintain a record of client <-> virtual IP address
# associations in this file.  If OpenVPN goes down or
# is restarted, reconnecting clients can be assigned
# the same virtual IP address from the pool that was
# previously assigned.
ifconfig-pool-persist ipp.txt

# Configure server mode for ethernet bridging.
# You must first use your OS's bridging capability
# to bridge the TAP interface with the ethernet
# NIC interface.  Then you must manually set the
# IP/netmask on the bridge interface, here we
# assume 10.8.0.4/255.255.255.0.  Finally we
# must set aside an IP range in this subnet
# (start=10.8.0.50 end=10.8.0.100) to allocate
# to connecting clients.  Leave this line commented
# out unless you are ethernet bridging.
;server-bridge 10.8.0.4 255.255.255.0 10.8.0.50 10.8.0.100

# Configure server mode for ethernet bridging
# using a DHCP-proxy, where clients talk
# to the OpenVPN server-side DHCP server
# to receive their IP address allocation
# and DNS server addresses.  You must first use
# your OS's bridging capability to bridge the TAP
# interface with the ethernet NIC interface.
# Note: this mode only works on clients (such as
# Windows), where the client-side TAP adapter is
# bound to a DHCP client.
;server-bridge

# Push routes to the client to allow it
# to reach other private subnets behind
# the server.  Remember that these
# private subnets will also need
# to know to route the OpenVPN client
# address pool (10.8.0.0/255.255.255.0)
# back to the OpenVPN server.
;push "route 192.168.10.0 255.255.255.0"
;push "route 192.168.20.0 255.255.255.0"

# To assign specific IP addresses to specific
# clients or if a connecting client has a private
# subnet behind it that should also have VPN access,
# use the subdirectory "ccd" for client-specific
# configuration files (see man page for more info).

# EXAMPLE: Suppose the client
# having the certificate common name "Thelonious"
# also has a small subnet behind his connecting
# machine, such as 192.168.40.128/255.255.255.248.
# First, uncomment out these lines:
;client-config-dir ccd
;route 192.168.40.128 255.255.255.248
# Then create a file ccd/Thelonious with this line:
#   iroute 192.168.40.128 255.255.255.248
# This will allow Thelonious' private subnet to
# access the VPN.  This example will only work
# if you are routing, not bridging, i.e. you are
# using "dev tun" and "server" directives.

# EXAMPLE: Suppose you want to give
# Thelonious a fixed VPN IP address of 10.9.0.1.
# First uncomment out these lines:
;client-config-dir ccd
;route 10.9.0.0 255.255.255.252
# Then add this line to ccd/Thelonious:
#   ifconfig-push 10.9.0.1 10.9.0.2

# Suppose that you want to enable different
# firewall access policies for different groups
# of clients.  There are two methods:
# (1) Run multiple OpenVPN daemons, one for each
#     group, and firewall the TUN/TAP interface
#     for each group/daemon appropriately.
# (2) (Advanced) Create a script to dynamically
#     modify the firewall in response to access
#     from different clients.  See man
#     page for more info on learn-address script.
;learn-address ./script

# If enabled, this directive will configure
# all clients to redirect their default
# network gateway through the VPN, causing
# all IP traffic such as web browsing and
# and DNS lookups to go through the VPN
# (The OpenVPN server machine may need to NAT
# or bridge the TUN/TAP interface to the internet
# in order for this to work properly).
push "redirect-gateway def1"


# Certain Windows-specific network settings
# can be pushed to clients, such as DNS
# or WINS server addresses.  CAVEAT:
# http://openvpn.net/faq.html#dhcpcaveats
# The addresses below refer to the public
# DNS servers provided by opendns.com.
push "dhcp-option DNS 10.8.0.1"
push "dhcp-option DNS 208.67.222.222"
push "dhcp-option DNS 208.67.220.220"

# Uncomment this directive to allow different
# clients to be able to "see" each other.
# By default, clients will only see the server.
# To force clients to only see the server, you
# will also need to appropriately firewall the
# server's TUN/TAP interface.
;client-to-client

# Uncomment this directive if multiple clients
# might connect with the same certificate/key
# files or common names.  This is recommended
# only for testing purposes.  For production use,
# each client should have its own certificate/key
# pair.
#
# IF YOU HAVE NOT GENERATED INDIVIDUAL
# CERTIFICATE/KEY PAIRS FOR EACH CLIENT,
# EACH HAVING ITS OWN UNIQUE "COMMON NAME",
# UNCOMMENT THIS LINE OUT.
;duplicate-cn

# The keepalive directive causes ping-like
# messages to be sent back and forth over
# the link so that each side knows when
# the other side has gone down.
# Ping every 10 seconds, assume that remote
# peer is down if no ping received during
# a 120 second time period.
keepalive 10 120

# For extra security beyond that provided
# by SSL/TLS, create an "HMAC firewall"
# to help block DoS attacks and UDP port flooding.
#
# Generate with:
#   openvpn --genkey --secret ta.key
#
# The server and each client must have
# a copy of this key.
# The second parameter should be '0'
# on the server and '1' on the clients.
;tls-auth ta.key 0 # This file is secret

# Select a cryptographic cipher.
# This config item must be copied to
# the client config file as well.
;cipher BF-CBC        # Blowfish (default)
;cipher AES-128-CBC   # AES
;cipher DES-EDE3-CBC  # Triple-DES
;cipher none
# Enable compression on the VPN link.
# If you enable it here, you must also
# enable it in the client config file.
;comp-lzo

# The maximum number of concurrently connected
# clients we want to allow.
;max-clients 100

# It's a good idea to reduce the OpenVPN
# daemon's privileges after initialization.
#
# You can uncomment this out on
# non-Windows systems.
;user nobody

;group nogroup

# The persist options will try to avoid
# accessing certain resources on restart
# that may no longer be accessible because
# of the privilege downgrade.
persist-key
persist-tun

# Output a short status file showing
# current connections, truncated
# and rewritten every minute.
status openvpn-status.log

# By default, log messages will go to the syslog (or
# on Windows, if running as a service, they will go to
# the "\Program Files\OpenVPN\log" directory).
# Use log or log-append to override this default.
# "log" will truncate the log file on OpenVPN startup,
# while "log-append" will append to it.  Use one
# or the other (but not both).
;log         openvpn.log
;log-append  openvpn.log

# Set the appropriate level of log
# file verbosity.
#
# 0 is silent, except for fatal errors
# 4 is reasonable for general usage
# 5 and 6 can help to debug connection problems
# 9 is extremely verbose
verb 3

# Silence repeating messages.  At most 20
# sequential messages of the same message
# category will be output to the log.
;mute 20
;sndbuf 393216
;rcvbuf 393216
;push "sndbuf 393216"
;push "rcvbuf 393216"

tun-mtu  64800
mssfix  1440
;fragment 0

Another configurations at server side about IP forward:

#!/bin/sh -e

#
# rc.local
#
# This script is executed at the end of each multiuser runlevel.
# Make sure that the script will "exit 0" on success or any other
# value on error.
#
# In order to enable or disable this script just change the execution
# bits.
#
# By default this script does nothing.
iptables -A FORWARD -m state --state RELATED,ESTABLISHED -j ACCEPT
iptables -A FORWARD -s 10.8.0.0/24 -j ACCEPT
iptables -A FORWARD -j REJECT
iptables -t nat -A POSTROUTING -s 10.8.0.0/24 -o eth0 -j MASQUERADE

service dnsmasq restart
exit 0

and net.ipv4.ip_forward=1

I set up an OpenVPN server at a remote cloud server, and config all routes to the dnsmasq that resides at the same OpenVPN server. I then downloaded all ca, and client keys in my local laptop. Once the laptop is connected to remote OpenVPN server, I would use DNS server at the OpenVPN server, and then all network connection would through the OpenVPN server.

Everything works ONLY when at my home. However， when I moved to another place (e.g., University office), all web sites could not be displayed. For exmaple, ping www.google.com on the console produces fails, while ping its IP address is OK.

hijiex@shijie-ThinkPad-T410:/other/dropxbox/Dropbox/project/IPRent/aliyun-us$ ping www.google.com
ping: unknown host www.google.com
shijiex@shijie-ThinkPad-T410:/other/dropxbox/Dropbox/project/IPRent/aliyun-us$ ping 199.212.24.179 (google's IP)
PING 199.212.24.179 (199.212.24.179) 56(84) bytes of data.
64 bytes from 199.212.24.179: icmp_seq=1 ttl=51 time=294 ms

shijiex@shijie-ThinkPad-T410:/other/projectbase/dacapo/benchmarks/bms/batik/src/org/dacapo/harness$ ping 10.8.0.1
PING 10.8.0.1 (10.8.0.1) 56(84) bytes of data.
64 bytes from 10.8.0.1: icmp_seq=1 ttl=64 time=38.0 ms
64 bytes from 10.8.0.1: icmp_seq=2 ttl=64 time=37.7 ms

The client.conf is

##############################################
# Sample client-side OpenVPN 2.0 config file #
# for connecting to multi-client server.     #
#                                            #
# This configuration can be used by multiple #
# clients, however each client should have   #
# its own cert and key files.                #
#                                            #
# On Windows, you might want to rename this  #
# file so it has a .ovpn extension           #
##############################################

# Specify that we are a client and that we
# will be pulling certain config file directives
# from the server.
client

# Use the same setting as you are using on
# the server.
# On most systems, the VPN will not function
# unless you partially or fully disable
# the firewall for the TUN/TAP interface.
;dev tap
dev tun

# Windows needs the TAP-Win32 adapter name
# from the Network Connections panel
# if you have more than one.  On XP SP2,
# you may need to disable the firewall
# for the TAP adapter.
;dev-node MyTap

# Are we connecting to a TCP or
# UDP server?  Use the same setting as
# on the server.
;proto tcp
proto udp

# The hostname/IP and port of the server.
# You can have multiple remote entries
# to load balance between the servers.
remote 47.90.206.48  1194
;remote my-server-2 1194

# Choose a random host from the remote
# list for load-balancing.  Otherwise
# try hosts in the order specified.
;remote-random

# Keep trying indefinitely to resolve the
# host name of the OpenVPN server.  Very useful
# on machines which are not permanently connected
# to the internet such as laptops.
resolv-retry infinite

# Most clients don't need to bind to
# a specific local port number.
nobind

# Downgrade privileges after initialization (non-Windows only)
;user nobody
;group nogroup

# Try to preserve some state across restarts.
persist-key
persist-tun

# If you are connecting through an
# HTTP proxy to reach the actual OpenVPN
# server, put the proxy server/IP and
# port number here.  See the man page
# if your proxy server requires
# authentication.
;http-proxy-retry # retry on connection failures
;http-proxy [proxy server] [proxy port #]

# Wireless networks often produce a lot
# of duplicate packets.  Set this flag
# to silence duplicate packet warnings.
;mute-replay-warnings

# SSL/TLS parms.
# See the server config file for more
# description.  It's best to use
# a separate .crt/.key file pair
# for each client.  A single ca
# file can be used for all clients.
ca ca.crt
cert aliyun-us.crt
key aliyun-us.key

# Verify server certificate by checking
# that the certicate has the nsCertType
# field set to "server".  This is an
# important precaution to protect against
# a potential attack discussed here:
#  http://openvpn.net/howto.html#mitm
#
# To use this feature, you will need to generate
# your server certificates with the nsCertType
# field set to "server".  The build-key-server
# script in the easy-rsa folder will do this.
ns-cert-type server

# If a tls-auth key is used on the server
# then every client must also have the key.
;tls-auth ta.key 1

# Select a cryptographic cipher.
# If the cipher option is used on the server
# then you must also specify it here.
;cipher x

# Enable compression on the VPN link.
# Don't enable this unless it is also
# enabled in the server config file.
comp-lzo

# Set log file verbosity.
verb 3

# Silence repeating messages
;mute 20

I checked the server and everything is still there. When I moved the laptop back to the home, it works again.

The　client's console:

Mon Apr  3 14:41:00 2017 Data Channel Encrypt: Cipher 'BF-CBC' initialized with 128 bit key
Mon Apr  3 14:41:00 2017 Data Channel Encrypt: Using 160 bit message hash 'SHA1' for HMAC authentication
Mon Apr  3 14:41:00 2017 Data Channel Decrypt: Cipher 'BF-CBC' initialized with 128 bit key
Mon Apr  3 14:41:00 2017 Data Channel Decrypt: Using 160 bit message hash 'SHA1' for HMAC authentication
Mon Apr  3 14:41:00 2017 Control Channel: TLSv1, cipher TLSv1/SSLv3 DHE-RSA-AES256-SHA, 2048 bit RSA
Mon Apr  3 14:41:00 2017 [server] Peer Connection Initiated with [AF_INET]47.90.206.48:1194
Mon Apr  3 14:41:03 2017 SENT CONTROL [server]: 'PUSH_REQUEST' (status=1)
Mon Apr  3 14:41:05 2017 PUSH: Received control message: 'PUSH_REPLY,redirect-gateway def1 bypass-dhcp,route 10.8.0.1,topology net30,ping 10,ping-restart 120,ifconfig 10.8.0.6 10.8.0.5'
Mon Apr  3 14:41:05 2017 OPTIONS IMPORT: timers and/or timeouts modified
Mon Apr  3 14:41:05 2017 OPTIONS IMPORT: --ifconfig/up options modified
Mon Apr  3 14:41:05 2017 OPTIONS IMPORT: route options modified
Mon Apr  3 14:41:05 2017 ROUTE_GATEWAY 131.202.102.1/255.255.255.0 IFACE=wlan0 HWADDR=00:23:14:40:24:84
Mon Apr  3 14:41:05 2017 TUN/TAP device tun0 opened
Mon Apr  3 14:41:05 2017 TUN/TAP TX queue length set to 100
Mon Apr  3 14:41:05 2017 do_ifconfig, tt->ipv6=0, tt->did_ifconfig_ipv6_setup=0
Mon Apr  3 14:41:05 2017 /sbin/ip link set dev tun0 up mtu 1500
Mon Apr  3 14:41:05 2017 /sbin/ip addr add dev tun0 local 10.8.0.6 peer 10.8.0.5
Mon Apr  3 14:41:05 2017 /sbin/ip route add 47.90.206.48/32 via 131.202.102.1
Mon Apr  3 14:41:05 2017 /sbin/ip route add 0.0.0.0/1 via 10.8.0.5
Mon Apr  3 14:41:05 2017 /sbin/ip route add 128.0.0.0/1 via 10.8.0.5
Mon Apr  3 14:41:05 2017 /sbin/ip route add 10.8.0.1/32 via 10.8.0.5
Mon Apr  3 14:41:05 2017 Initialization Sequence Completed

Updated VPN server.conf:

# Which local IP address should OpenVPN
# listen on? (optional)
;local a.b.c.d

# Which TCP/UDP port should OpenVPN listen on?
# If you want to run multiple OpenVPN instances
# on the same machine, use a different port
# number for each one.  You will need to
# open up this port on your firewall.
port 1194

# TCP or UDP server?
;proto tcp
proto udp

# "dev tun" will create a routed IP tunnel,
# "dev tap" will create an ethernet tunnel.
# Use "dev tap0" if you are ethernet bridging
# and have precreated a tap0 virtual interface
# and bridged it with your ethernet interface.
# If you want to control access policies
# over the VPN, you must create firewall
# rules for the the TUN/TAP interface.
# On non-Windows systems, you can give
# an explicit unit number, such as tun0.
# On Windows, use "dev-node" for this.
# On most systems, the VPN will not function
# unless you partially or fully disable
# the firewall for the TUN/TAP interface.
;dev tap
dev tun

# Windows needs the TAP-Win32 adapter name
# from the Network Connections panel if you
# have more than one.  On XP SP2 or higher,
# you may need to selectively disable the
# Windows firewall for the TAP adapter.
# Non-Windows systems usually don't need this.
;dev-node MyTap

# SSL/TLS root certificate (ca), certificate
# (cert), and private key (key).  Each client
# and the server must have their own cert and
# key file.  The server and all clients will
# use the same ca file.
#
# See the "easy-rsa" directory for a series
# of scripts for generating RSA certificates
# and private keys.  Remember to use
# a unique Common Name for the server
# and each of the client certificates.
#
# Any X509 key management system can be used.
# OpenVPN can also use a PKCS #12 formatted key file
# (see "pkcs12" directive in man page).
ca ca.crt
cert server.crt
key server.key  # This file should be kept secret

# Diffie hellman parameters.
# Generate your own with:
#   openssl dhparam -out dh2048.pem 2048
dh dh2048.pem

# Network topology
# Should be subnet (addressing via IP)
# unless Windows clients v2.0.9 and lower have to
# be supported (then net30, i.e. a /30 per client)
# Defaults to net30 (not recommended)
;topology subnet

# Configure server mode and supply a VPN subnet
# for OpenVPN to draw client addresses from.
# The server will take 10.8.0.1 for itself,
# the rest will be made available to clients.
# Each client will be able to reach the server
# on 10.8.0.1. Comment this line out if you are
# ethernet bridging. See the man page for more info.
server 10.8.0.0 255.255.255.0

# Maintain a record of client <-> virtual IP address
# associations in this file.  If OpenVPN goes down or
# is restarted, reconnecting clients can be assigned
# the same virtual IP address from the pool that was
# previously assigned.
ifconfig-pool-persist ipp.txt

# Configure server mode for ethernet bridging.
# You must first use your OS's bridging capability
# to bridge the TAP interface with the ethernet
# NIC interface.  Then you must manually set the
# IP/netmask on the bridge interface, here we
# assume 10.8.0.4/255.255.255.0.  Finally we
# must set aside an IP range in this subnet
# (start=10.8.0.50 end=10.8.0.100) to allocate
# to connecting clients.  Leave this line commented
# out unless you are ethernet bridging.
;server-bridge 10.8.0.4 255.255.255.0 10.8.0.50 10.8.0.100

# Configure server mode for ethernet bridging
# using a DHCP-proxy, where clients talk
# to the OpenVPN server-side DHCP server
# to receive their IP address allocation
# and DNS server addresses.  You must first use
# your OS's bridging capability to bridge the TAP
# interface with the ethernet NIC interface.
# Note: this mode only works on clients (such as
# Windows), where the client-side TAP adapter is
# bound to a DHCP client.
;server-bridge

# Push routes to the client to allow it
# to reach other private subnets behind
# the server.  Remember that these
# private subnets will also need
# to know to route the OpenVPN client
# address pool (10.8.0.0/255.255.255.0)
# back to the OpenVPN server.
;push "route 192.168.10.0 255.255.255.0"
;push "route 192.168.20.0 255.255.255.0"

# To assign specific IP addresses to specific
# clients or if a connecting client has a private
# subnet behind it that should also have VPN access,
# use the subdirectory "ccd" for client-specific
# configuration files (see man page for more info).

# EXAMPLE: Suppose the client
# having the certificate common name "Thelonious"
# also has a small subnet behind his connecting
# machine, such as 192.168.40.128/255.255.255.248.
# First, uncomment out these lines:
;client-config-dir ccd
;route 192.168.40.128 255.255.255.248
# Then create a file ccd/Thelonious with this line:
#   iroute 192.168.40.128 255.255.255.248
# This will allow Thelonious' private subnet to
# access the VPN.  This example will only work
# if you are routing, not bridging, i.e. you are
# using "dev tun" and "server" directives.

# EXAMPLE: Suppose you want to give
# Thelonious a fixed VPN IP address of 10.9.0.1.
# First uncomment out these lines:
;client-config-dir ccd
;route 10.9.0.0 255.255.255.252
# Then add this line to ccd/Thelonious:
#   ifconfig-push 10.9.0.1 10.9.0.2

# Suppose that you want to enable different
# firewall access policies for different groups
# of clients.  There are two methods:
# (1) Run multiple OpenVPN daemons, one for each
#     group, and firewall the TUN/TAP interface
#     for each group/daemon appropriately.
# (2) (Advanced) Create a script to dynamically
#     modify the firewall in response to access
#     from different clients.  See man
#     page for more info on learn-address script.
;learn-address ./script

# If enabled, this directive will configure
# all clients to redirect their default
# network gateway through the VPN, causing
# all IP traffic such as web browsing and
# and DNS lookups to go through the VPN
# (The OpenVPN server machine may need to NAT
# or bridge the TUN/TAP interface to the internet
# in order for this to work properly).
;push "redirect-gateway def1 bypass-dhcp"

# Certain Windows-specific network settings
# can be pushed to clients, such as DNS
# or WINS server addresses.  CAVEAT:
# http://openvpn.net/faq.html#dhcpcaveats
# The addresses below refer to the public
# DNS servers provided by opendns.com.
push "dhcp-option DNS 208.67.222.222"
push "dhcp-option DNS 208.67.220.220"

# Uncomment this directive to allow different
# clients to be able to "see" each other.
# By default, clients will only see the server.
# To force clients to only see the server, you
# will also need to appropriately firewall the
# server's TUN/TAP interface.
;client-to-client

# Uncomment this directive if multiple clients
# might connect with the same certificate/key
# files or common names.  This is recommended
# only for testing purposes.  For production use,
# each client should have its own certificate/key
# pair.
#
# IF YOU HAVE NOT GENERATED INDIVIDUAL
# CERTIFICATE/KEY PAIRS FOR EACH CLIENT,
# EACH HAVING ITS OWN UNIQUE "COMMON NAME",
# UNCOMMENT THIS LINE OUT.
;duplicate-cn

# The keepalive directive causes ping-like
# messages to be sent back and forth over
# the link so that each side knows when
# the other side has gone down.
# Ping every 10 seconds, assume that remote
# peer is down if no ping received during
# a 120 second time period.
keepalive 10 120

# For extra security beyond that provided
# by SSL/TLS, create an "HMAC firewall"
# to help block DoS attacks and UDP port flooding.
#
# Generate with:
#   openvpn --genkey --secret ta.key
#
# The server and each client must have
# a copy of this key.
# The second parameter should be '0'
# on the server and '1' on the clients.
;tls-auth ta.key 0 # This file is secret

# Select a cryptographic cipher.
# This config item must be copied to
# the client config file as well.
;cipher BF-CBC        # Blowfish (default)
;cipher AES-128-CBC   # AES
;cipher DES-EDE3-CBC  # Triple-DES

# Enable compression on the VPN link.
# If you enable it here, you must also
# enable it in the client config file.
comp-lzo

# The maximum number of concurrently connected
# clients we want to allow.
;max-clients 100

# It's a good idea to reduce the OpenVPN
# daemon's privileges after initialization.
#
# You can uncomment this out on
# non-Windows systems.
;user nobody

;group nogroup

# The persist options will try to avoid
# accessing certain resources on restart
# that may no longer be accessible because
# of the privilege downgrade.
persist-key
persist-tun

# Output a short status file showing
# current connections, truncated
# and rewritten every minute.
status openvpn-status.log

# By default, log messages will go to the syslog (or
# on Windows, if running as a service, they will go to
# the "\Program Files\OpenVPN\log" directory).
# Use log or log-append to override this default.
# "log" will truncate the log file on OpenVPN startup,
# while "log-append" will append to it.  Use one
# or the other (but not both).
;log         openvpn.log
;log-append  openvpn.log

# Set the appropriate level of log
# file verbosity.
#
# 0 is silent, except for fatal errors
# 4 is reasonable for general usage
# 5 and 6 can help to debug connection problems
# 9 is extremely verbose
verb 3

# Silence repeating messages.  At most 20
# sequential messages of the same message
# category will be output to the log.
;mute 20
;push "redirect-gateway def1" push "dhcp-option DNS 10.8.0.1"
push "redirect-gateway def1 bypass-dhcp"
;push "redirect-gateway def1"

/etc/rc.local:

#!/bin/sh -e

#
# rc.local
#
# This script is executed at the end of each multiuser runlevel.
# Make sure that the script will "exit 0" on success or any other
# value on error.
#
# In order to enable or disable this script just change the execution
# bits.
#
# By default this script does nothing.
iptables -A FORWARD -m state --state RELATED,ESTABLISHED -j ACCEPT
iptables -A FORWARD -s 10.8.0.0/24 -j ACCEPT
iptables -A FORWARD -j REJECT
iptables -t nat -A POSTROUTING -s 10.8.0.0/24 -o eth0 -j MASQUERADE

service dnsmasq restart
exit 0

and /etc/sysctl.conf: net.ipv4.ip_forward=1

I also configured the IP forward rules at the server side.

Thanks

I am looking for a command (may be two) that can shows the path to a remote server(e.g., www.google.com).

For a server, this command first lists the DNS server I used, and then shows each network hops, when it is on the way to the given IP address, which is resolved from DNS lookup.

I am trying to install an openvpn Software Packages at a new EC2 instance. After running: sudo dpkg -i openvpn-as-2.1.4b-Ubuntu16.amd_64.deb

The deb package is downloaded from https://openvpn.net/index.php/access-server/download-openvpn-as-sw/113.html?osfamily=Ubuntu

The message shows the installation fails, and the message in the log is:

Once you provide a few initial configuration settings,
OpenVPN Access Server can be configured by accessing
its Admin Web UI using your Web browser.

Will this be the primary Access Server node?
(enter 'no' to configure as a backup or standby node)
> Press ENTER for default [yes]: 

Please specify the network interface and IP address to be
used by the Admin Web UI:
(1) all interfaces: 0.0.0.0
(2) eth0: 172.31.23.191
Please enter the option number from the list above (1-2).
> Press Enter for default [2]: 

Please specify the port number for the Admin Web UI.
> Press ENTER for default [943]: 

Please specify the TCP port number for the OpenVPN Daemon
> Press ENTER for default [443]: 

Should client traffic be routed by default through the VPN?
> Press ENTER for default [yes]: 

Should client DNS traffic be routed by default through the VPN?
> Press ENTER for default [yes]: 

Use local authentication via internal DB?
> Press ENTER for default [no]: 
Traceback (most recent call last):
  File "/usr/local/openvpn_as/bin/_ovpn-init", line 478, in <module>
    priv_nets = NetInfoLinux.get_priv_subnets()
  File "build/bdist.linux-x86_64/egg/pyovpn/net/net.py", line 403, in get_priv_subnets
AttributeError: type object 'IP' has no attribute 'SubnetSet'

The OS: Linux ip-172-31-23-191 3.13.0-106-generic #153-Ubuntu SMP Tue Dec 6 15:44:32 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux and Python is　２．７．６

Any help? Thanks

My home directory is nearly completely occupied.

/dev/sda7        28G   24G  2.1G  93% /home

disk analysis shows the top largest directory is .thunderbird. As shown in the screenshot. Is there any other way to optimize it, or solution for it, so that I can have more space at /home?

I have installed ubuntu in my computer, later, I format a partition as linux swap and want to replace it with existing tmp directory under mount point /. I followed procedure given in this link: http://ubuntuforums.org/showthread.php?t=1670222 . The question is that the swap is still not enabled. Here is some command output.

shijiex@shijie-ThinkPad-T410:~$ df 
Filesystem     1K-blocks     Used Available Use% Mounted on
/dev/sda1       28703740  5324096  21914916  20% /
tmpfs            1180916      924   1179992   1% /run
.........
/dev/sda7       28706812 17150036  10091896  63% /home
shijiex@shijie-ThinkPad-T410:~$ sudo blkid -c /dev/null -o list 
device         fs_type  label     mount point        UUID
-----------------------------------------------------------------------
/dev/sda1      ext4               /                  47d9205b-00a8-40e5-88d6-e8b9571799a7
...
/dev/sda7      ext4               /home              e2ae897d-62b1-45d3-a17a-49e7a1b8fbe7
/dev/sda9      swap               <swap>             81ce2033-4ff2-4e05-9500-aacfd1019855

shijiex@shijie-ThinkPad-T410:~$ sudo mount
/dev/sda1 on / type ext4 (rw,errors=remount-ro)
udev on /dev type devtmpfs (rw,mode=0755)
devpts on /dev/pts type devpts (rw,noexec,nosuid,gid=5,mode=0620)
tmpfs on /run type tmpfs (rw,noexec,nosuid,size=10%,mode=0755)
 ......
/dev/sda8 on /opt type ext4 (rw)
/dev/sda5 on /backup type ext4 (rw)
/dev/sda6 on /other type ext4 (rw)
/dev/sda7 on /home type ext4 (rw)
binfmt_misc on /proc/sys/fs/binfmt_misc type binfmt_misc (rw,noexec,nosuid,nodev)
gvfs-fuse-daemon on /home/shijiex/.gvfs type fuse.gvfs-fuse-daemon (rw,nosuid,nodev,user=shijiex)

At the end of /etc/fstab, it is:

# swap was on /dev/sda9 during installation
UUID=81ce2033-4ff2-4e05-9500-aacfd1019855  none            swap    sw              0       0

shijiex@shijie-ThinkPad-T410:~$ df 
Filesystem     1K-blocks     Used Available Use% Mounted on
/dev/sda1       28703740  5324100  21914912  20% /
udev             2942940        4   2942936   1% /dev
tmpfs            1180916      924   1179992   1% /run
none                5120        0      5120   0% /run/lock
none             2952280      156   2952124   1% /run/shm

/dev/sda8 14286320 11978284 1575672 89% /opt /dev/sda5 38317716 36097448 267144 100% /backup /dev/sda6 85532500 35151740 46029084 44% /other /dev/sda7 28706812 17150392 10091540 63% /home

The swap partition is sda9.I am not sure whether swap is enabled, because:

1. /dev/sda9 is not in list of df result. While previously it always should be like:

   /dev/sda9       28706812 17150392  10091540  63% /tmp
   

2. Gpart shows that /dev/sda9 as linux-swap with 14.85G,

   used     unused 
   --        --
   

3. I was unable to access swap area. Previously, swap was always mount as /tmp and I can access this directory. Now the /tmp is only a directory under /..

4. The OS is ubuntu 12.04 lts..

[UPDATE]:

The swap should have been enabled, cat /proc/swaps:

/dev/sda9                               partition   15575036    0   -1

though the used size is 0.

Now the scenario is:

I already have tmp directory under /, how can I mount swap this partition as mount point is /tmp. I modified last line of fstab as:

UUID=81ce2033-4ff2-4e05-9500-aacfd1019855  /tmp            swap    sw              0       0

Then mount -a and reboot does not report any error. But used in swap is 0 though I dumped many file content to /tmp.

So how can I fully utilized swap area, which is almost 15G? It is waste of disk if it always 0 used..

Or how can I just change /tmp to the swap partition?

I want this because this directory is widely used in my program and it is also as exchange area between my Ubuntu and hosted WindowXP. Both requires large disk space..