vim Function List

Install ctags

yum install ctags

Download and install vim taglist

Download taglist _45.zip from webpage http://vim.sourceforge.net/scripts/script.php?script_id=273

Unzip

unzip taglist_45.zip

Move plugin and doc to ~/.vim/

mv plugin doc ~/.vim/

Add "map <f9> :Tlist<CR>" to "/etc/vimrc"

echo "map <f9> :Tlist<CR>" >> /etc/vimrc

Use ctags in working directory

ctags -R *.c *.cpp *.h

Edit your source file

vim xxx.cpp

Toggle function list

Press <F9>

OpenVPN with Public IP Assignments

OpenVPN with Public IP Assignments

VPN Server IP 
                a.b.c.99

VPN Subnet IP
                a.b.c.104 ~ a.b.c.107 (255.255.255.252)

VPN Server tun IP(a.b.c.105)
                a.b.c.105

Client tun IP   (a.b.c.106)
                a.b.c.106

Route:
                Use VPN server as default route

 


Server (a.b.c.99)
#Create conf

vi /etc/openvpn

# VPN server tun IP and VPN subnet netmask (size)
ifconfig a.b.c.105 255.255.255.252

# Some common settings
port 1194
proto tcp-server
mode server
tls-server
dev tun
ca ca.crt
cert server.crt
key server.key
dh dh2048.pem
keepalive 10 120
comp-lzo

# VPN IP pool
ifconfig-pool a.b.c.106 a.b.c.107
# Use VPN server tun IP as gateway for VPN subnet
push "route-gateway a.b.c.105"
# vpn server use tun as route dev for vpn subnet
topology subnet
# vpn client use tun as route devo for vpn subnet
push "topology subnet"
#  Use VPN server as default gateway
push "redirect-gateway def1 bypass-dhcp"
# Make VPN client user use 8.8.8.8 as defualt DNS
push "dhcp-option DNS 8.8.8.8"
#Enable Client to client traffic
client-to-client

#Enable forward

iptables -I FORWARD -j ACCEPT

OpenVPN

Server (IP 1.2.3.4, VPN Subnet 10.8.0.0 / 255.255.255.0)

Install OpenVPN

yum install openvpn

Generate Certificates (by using easy-rsa)

cd /usr/share/openvpn/easy-rsa/2.0/

#Setup parameters for certificate key generation

vi vars

source ./vars

#Clean all generated certificates and keys

./clean-all

#Generate server certificate

./build-ca

#Generate server key

./build-key-sever server

#Generate client key

./build-key client1

#Generate Diffie Hellman parameters

./build-dh

#Copy keys and certificates to openvpn conf folder (*crt: certificates; *key: private keys)

cd keys
cp -a ca.crt server.crt server.key dh1024.pem /etc/openvpn/

Create configuration

#copy sampel conf file to openvpn conf folder

cp -a /usr/share/doc/openvpn-x.x.x/sample-config-files/server.conf /etc/openvpn/

#Edit conf file

vi /etc/openvpn/server.conf

#Server IP

local 1.2.3.4

#Listen port

port 1194

#protocol tcp or udp (default)

proto tcp

#tunnel tun (default) or tap

dev tun

#SSL/TLS Certificate

ca ca.crt

#Certificate

cert server.crt

#Private key

key server.key

#Diffie hellman

dh dh1024.pem

#VPN subnet, comment out for bridge mode

server 10.8.0.0 255.255.255.0

#Persistent assignment and log filename

ifconfig-pool-persist ipp.txt

#bridge mode(10.8.0.4/255.25.255.0: ip and nm of bridge interface; ip pool 10.8.0.50 ~ 10.8.0.100)

;server-bridge 10.8.0.4 255.255.255.0 10.8.0.50 10.8.0.100

#DHCP-proxy (use Server-side DHCP server to assign client IP)

;server-bridge

#enable compression

comp-lzo

#Maximum number of concurrently connected clients

;max-clients 100

#Server status

status openvpn-status.log

#Log

log-append

#verbosity

verb 3

#Start OpenVPN Service

service openvpn@server.service

Client

#Download ca.crt, client.crt, client.key from Server

cp -a ca.crt client1.crt client.key MyClient

#Copy sample client conf to folder

cp -a /usr/share/doc/openvpn-x.x.x/sample-config-files/client.conf MyClient

#Modify client conf (Linux) / ovpn file (windows)

#

vi client.conf

dev tun

proto tcp

remote 1.2.3.4 1194

ca ca.crt

cert client1.crt

key client1.key

#Execute client with .conf file

openvpn xxx.conf

#Execute client with .ovpn file

<Right-click ovpn file and select “Start OpenVPN on this config file” in Windows>

SSH VPN with remote routing

VPN Client
tun0 Private IP	192.168.100.253
VPN Server
tun0 Private IP	192.168.100.254
Public IP	1.2.3.4
Public Interface	eth0

Server

Install Packages

yum install tunctl

Create tun0

tunctl -t tun0

Configure tun0

ifconfig tun0 192.168.100.254 netmask 255.255.255.0 pointopoint 192.168.100.253

Configure sshd for tunnel

vi /etc/ssh/sshd_config

PermitTunnel yes

Restart sshd for Modified Configuration

service sshd restart

Enable forward

sysctl –w net.ipv4.ip_forward=1

iptables -I FORWARD -i tun0 -o eth0 -j ACCEPT

iptables -I FORWARD -i eth0 -o tun0 -j ACCEPT

iptables -t nat -A POSTROUTING -s 192.168.100.253/24 -o eth0 -j MASQUERADE

Local

Install Packages

yum install tunctl

Create tun0

tunctl -t tun0

Configure tun0

ifconfig tun0 192.168.100.253 netmask 255.255.255.0 pointopoint 192.168.100.254

Connect

ssh -w0:0 1.2.3.4

Configure routing (special destination goes through remote gateway / VPN Server)

route add -net some_ip/prefix dev tun0
(e.g. route add -net 140.112.31.0/24 dev tun0)

 

Linux Network Address Translation (NAT) Service

Variables
    iif: your intranet interface
    iip: your intranet IP
    wif: your internet (WAN) interface
    wip: your wan internet (WAN) IP
    inm: your intranet netmask


Enable Forwarding
    echo 1 > /proc/sys/net/ipv4/ip_forward

Enable IP Forwarding

1.      iptables -I FORWARD -i $wif -o $iif -j ACCEPT
2.      iptables -I FORWARD -i $iif -o $wif -j ACCEPT
3.      iptables -t nat -A POSTROUTING -s $iip/$inm -o $wif -j MASQUERADE

               OR 

     iptables -t nat -I POSTROUTING -s $iip/$inm -j SNAT --to $wip