linux下网络小常识！

1.检测服务器上ip地址是否生效/可用的方法

ping g.cn -I 服务器ip 表示使用本机的指定ip ping g.cn 如果可以ping通则表示正常

例如：美国刚买的ip 23.234.200.0/24

[root@PDS794 ~]# ping g.cn -I 23.234.200.251

PING g.cn (173.194.79.160) from 23.234.200.251 : 56(84) bytes of data.

64 bytes from pb-in-f160.1e100.net (173.194.79.160): icmp_seq=1 ttl=51 time=26.5 ms

64 bytes from pb-in-f160.1e100.net (173.194.79.160): icmp_seq=2 ttl=51 time=26.5 ms

64 bytes from pb-in-f160.1e100.net (173.194.79.160): icmp_seq=3 ttl=51 time=26.7 ms

2.通道的建立

例如： bj06-us01 1.54.16.1-2 210.51.3.31-198.148.124.34

cat >> /etc/rc.local <<\EOF

#bj06-us01

ip tunnel add bj06-us01 mode ipip remote 198.148.124.34 local 210.51.3.31

ip add add dev bj06-us01 1.54.16.1 peer 1.54.16.2

ifconfig bj06-us01 1.54.16.1/30

ip link set bj06-us01 up

route add -host 1.54.16.2 dev bj06-us01

EOF

#us01-bj06

ip tunnel add us01-bj06 mode ipip remote 210.51.3.31 local 198.148.124.34

ip add add dev us01-bj06 1.54.16.2 peer 1.54.16.1

ifconfig us01-bj06 1.54.16.2/30

ip link set us01-bj06 up

route add -host 1.54.16.1 dev us01-bj06

测试结果：

[root@bj06 ~]# alias ips

alias ips='ip route show'

[root@bj06 ~]# ips |grep us01

1.54.16.2 dev bj06-us01 scope link

1.54.16.0/30 dev bj06-us01 proto kernel scope link src 1.54.16.1

203.117.0.0/16 via 1.54.16.2 dev bj06-us01

[root@bj06 ~]# alias p

alias p='ping'

[root@bj06 ~]# p 1.54.16.2

PING 1.54.16.2 (1.54.16.2) 56(84) bytes of data.

64 bytes from 1.54.16.2: icmp_seq=1 ttl=64 time=223 ms

64 bytes from 1.54.16.2: icmp_seq=2 ttl=64 time=223 ms

64 bytes from 1.54.16.2: icmp_seq=3 ttl=64 time=224 ms

要改3个地方

1.私网ip 1.54.16.1-2

2.公网ip 210.51.3.31-198.148.124.34

3.接口名称 dev bj06-us01

为什么要建立通道

通过路由转发 如 ip route replace 这种方法比较灵活 比如说访问台服与国服使用不同的路由 如访问203.66.0.0/16(台服魔兽ip段)时走中台的路由 而访问国服魔兽(123.125.0.0/16)可以走到北京的路由

可以挡攻击 使用路由切换程序可以挡流量攻击

3. 163yum源

#换成163的yum源：

cd /etc/yum.repos.d

mv CentOS-Base.repo CentOS-Base.repo.save

wget mirrors.163.com/.help/CentOS 5 -Base-163.repo

#wget mirrors.163.com/.help/CentOS 6 -Base-163.repo

sed -i 's/enabled=1/enabled=0/g' /etc/yum/pluginconf.d/fastestmirror.conf

cat /dev/null > /var/cache/yum/timedhosts.txt

yum clean all

yum makecache

[root@bj06 yum.repos.d]# ls /etc/yum.repos.d/

CentOS6-Base-163.repo CentOS-Debuginfo.repo CentOS-Vault.repo epel-testing.repo

CentOS-Base.repo CentOS-Media.repo epel.repo

除了它，其他的都可以备份下，暂时不用！

4.默认路由

查默认路由

[root@bj02 ~]# ip route show |grep def

default via 1.27.10.1 dev bj02-gz02c

查通道信息：

[root@bj02 ~]# ifconfig |grep bj02-gz02c -A 6

bj02-gz02c Link encap:IPIP Tunnel HWaddr

inet addr:1.27.10.2 P-t-P:1.27.10.1 Mask:255.255.255.252

UP POINTOPOINT RUNNING NOARP MTU:1480 Metric:1

RX packets:1488769604 errors:0 dropped:0 overruns:0 frame:0

TX packets:1702443750 errors:0 dropped:0 overruns:0 carrier:0

collisions:0 txqueuelen:0

RX bytes:2923348000 (2.7 GiB) TX bytes:99236479 (94.6 MiB)

[root@bj02 ~]# cat /etc/rc.local |grep bj02- gz02c 可查出对端的ip

#bj02-gz02c

ip tunnel add bj02-gz02c mode ipip remote 116.213.249.196 local 202.108.54.10

ip add add dev bj02-gz02c 1.27.10.2 peer 1.27.10.1

ifconfig bj02-gz02c 1.27.10.2/30

ip link set bj02-gz02c up

route add -host 1.27.10.1 dev bj02-gz02c

ip route replace default via 1.27.10.1 dev bj02-gz02c

拥有国际出口的默认路由：

[root@gz02 ~]# ifconfig |grep 116.213.249.196

inet addr:116.213.249.196 Bcast:116.213.249.223 Mask:255.255.255.224

[root@gz02 ~]# ip route show |grep default

default via 203.78.190.14 dev em2 直接从接口出去

You have new mail in /var/spool/mail/roo

如何修改默认路由：

[root@bj02 ~]# ip ro re 0.0.0.0/0 via 1.54.10.1 dev bj02-bj06

[root@bj02 ~]# ips |grep def

default via 1.54.10.1 dev bj02-bj06

调整路由的方法和修改默认路由的方法类似，如把 台服lol的认证ip 203.117网段通过bj06通过通道送出去

ip ro re 203.117.0.0/16 via 1.54.16.2 dev bj06-us01