nftables 也有表、规则链、规则的概念：
表是规则链的容器
表有几个family: ip/ip6/inet/arp/bridge/netdev; inet=ip和ip6的混合
链是规则的容器
基本链的类型有：
filter: 支持ip/ip6/inet/arp/bridge；不支持netdev(好像能支持？)
route: 标记数据包，支持ip和ip6，只能用于output钩子。该功能类似iptables的mangle
nat: NAT功能，支持ip和ip6.
基本链的钩子(hook)有：
ip/ip6/inet的钩子有: prerouting，input, forward, output, postrouting.
arp的钩子有: input, output.
netdev的钩子有：ingress
链的优先级有： 数据包会遍历钩子上的链，直到走完所有链或被丢弃。以下是iptables的优先级参考
here's the list of different priority used in iptables:
NF_IP_PRI_CONNTRACK_DEFRAG (-400): priority of defragmentation
NF_IP_PRI_RAW (-300): traditional priority of the raw table placed before connection tracking operation
NF_IP_PRI_SELINUX_FIRST (-225): SELinux operations
NF_IP_PRI_CONNTRACK (-200): Connection tracking operations
NF_IP_PRI_MANGLE (-150): mangle operation
NF_IP_PRI_NAT_DST (-100): destination NAT
NF_IP_PRI_FILTER (0): filtering operation, the filter table
NF_IP_PRI_SECURITY (50): Place of security table where secmark can be set for example
NF_IP_PRI_NAT_SRC (100): source NAT
NF_IP_PRI_SELINUX_LAST (225): SELinux at packet exit
NF_IP_PRI_CONNTRACK_HELPER (300): connection tracking at exit
链的默认策略有：accept, drop, queue, continue, return.
规则：
handle 标识某个规则的数字，句柄号。插入规则的时候，position后就需要这个句柄号来定义位置。
matches 用于创建过滤器的匹配： matches很繁杂，具体参考https://wiki.nftables.org/wiki-nftables/index.php/Quick_reference-nftables_in_10_minutes
statement 数据包匹配后执行的语句。有log/reject/counter/limit/nat/queue/verdict statement。其中verdict statement可选值为：
accept: Accept the packet and stop the remain rules evaluation.
drop: Drop the packet and stop the remain rules evaluation.
queue: Queue the packet to userspace and stop the remain rules evaluation.
continue: Continue the ruleset evaluation with the next rule.
return: Return from the current chain and continue at the next rule of the last chain. In a base chain it is equivalent to accept
jump <chain>: Continue at the first rule of <chain>. It will continue at the next rule after a return statement is issued
goto <chain>: Similar to jump, but after the new chain the evaluation will continue at the last chain instead of the one containing the goto statement
钩子之间的关系：
Local
process
^ | .-----------.
.-----------. | | | Routing |
| |-----> input / \---> | Decision |----> output \
--> prerouting --->| Routing | .-----------. \
| Decision | --> postrouting
| | /
| |---------------> forward ---------------------------
.-----------.
4.2内核后多了ingress钩子，ingress钩子与其他钩子的关系如下：
.-----------.
| |-----> input ...
---> ingress ---> prerouting --->| Routing |
| Decision |
| |
| |-----> forward ...
.-----------.
命令行语法：
表操作：
% nft list tables [<family>] # 显示所有表， 如果family不指定，则默认ip.
% nft list table [<family>] <name> [-n] [-a] # 显示name指定的表， -n 表示数字形式显示 -a表示显示handle
% nft (add | delete | flush) table [<family>] <name>
链操作：
% nft (add|create) chain [<family>] <table> <name> [ { type <type> hook <hook> [device <device>] priority <priority> \; [policy <policy> \;] } ] *注释1*
% nft (delete | list | flush) chain [<family>] <table> <name>
% nft rename chain [<family>] <table> <name> <newname>
规则操作：
% nft add rule [<family>] <table> <chain> <matches> <statements>
% nft insert rule [<family>] <table> <chain> [position <position>] <matches> <statements>
% nft replace rule [<family>] <table> <chain> [handle <handle>] <matches> <statements>
% nft delete rule [<family>] <table> <chain> [handle <handle>]
其他：导出配置： % nft export (xml | json)
事件监控： % nft monitor [new | destroy] [tables | chains | sets | rules | elements] [xml | json]
注释1： 链配置中的policy用来指定该链的默认策略。如果链配置不指定，则创建了一条看不到任何包的非基本链(类似iptables的自定义链) 。如果是netdev类型的链，必须要指定接口设备
命令行示例：
# ------- 表操作 ----------
% nft add table ip tbl_test1
% nft flush table ip tbl_test1 # 清掉tbl_test1表的所有规则
# ------- 链操作 ---------
% nft add chain ip tbl_test1 chn_test1 {type filter hook input priority 0\; policy accept\;} # 花括号内的是链配置，bash中分号需要转义，如果不想转义，可以写成'{链配置}'的形式。 priority用来定义链的优先级
% nft add chain netdev tbl_test2 chn_eth0filter '{type filter hook ingress device eth0 priority 0; }' # netdev类型的表必须指定接口
% nft add chain ip tbl_test1 nonBaseChain2 # 创建一条非基本链，因为非基本链没有挂任何钩子，所以它不能看到任何数据包。它用于排列规则集合(jump到该链)
% nft delete chain ip tbl_test1 chn_test1 # 删除链，删除前需要flush以下该链(nft flush chain tbl_test1 chn_test1)，才能删除
# ------- 规则操作 ---------
% nft add rule tbl_test chn_test1 ip daddr 8.8.8.8 counter # 目标地址为8.8.8.8的做计数, 使用nft list table tbl_name -nn 来查看表下的规则
% nft add rule tbl_test1 chn_test1 tcp dport != 22 accept # 运算符可以有 ==, !=, <=, >=, >, < 如果在bash中，需要\转义，或者使用eq ne le ge gt lt来代替
% nft add rule tbl_test1 chn_test1 position 2 ip daddr 127.0.0.9 drop # position指定相对位置，后跟handle号。add是在后面添加，insert是在前面插入。(每条规则都有handle号，nft list tbl_name -n -a就可以查看句柄号)。
% nft replace rule tbl_test1 chn_test handle 3 ip daddr 127.0.0.10 drop # 替换handle指定的规则规则
% nft delete rule tbl_test1 chn_test handle 3 #删除某规则
% nft add rule tbl_test1 chn_test ip6 nexthdr tcp # ip6下的tcp
# --------导入导出、脚本操作--------
% cat << EOF > /etc/nftables.rules > #!/usr/local/sbin/nft -f > flush ruleset > add table filter > add chain filter input > add rule filter input meta iifname lo accept > EOF % chmod u+x /etc/nftables.rules % /etc/nftables.rules # 使用nft脚本执行。注意上面的解释器： #!/usr/local/sbin/nft
% nft list ruleset > /etc/nftables.rules # 导出规则集合 % nft flush ruleset # 冲掉规则集 % nft -f /etc/nftables.rules # 导入规则集合(记得先flush规则集，然后再导入)
# ------ 规则集合 -----
% nft list ruleset # 列出规则集
% nft list ruleset ip6 # 列出ip6规则集
% nft flush ruleset ip6 # 冲掉ip6规则集
% nft export json >ruleset.json #导出规则集为json
脚本：
可以include,例如:
#!/usr/sbin/nft -f
include "ipv4-nat.ruleset"
include "ipv6-nat.ruleset"
定义变量：
define google_dns = 8.8.8.8 #引用示例： add rule tb2 chn2 ip saddr $google_dns counter
define ntp_server_set = { 84.77.40.132, 176.31.53.99, 81.19.96.148, 138.100.62.8 } #引用示例：add rule tb2 chn2 ip saddr $ntp_server_set counter
格式：
#格式1：
#!/usr/sbin/nft -f
define ntp_servers = { 84.77.40.132, 176.31.53.99, 81.19.96.148, 138.100.62.8 }
#flush table nat
table ip nat {
chain prerouting {
type filter hook prerouting priority 0; policy accept;
ip saddr $ntp_servers counter
}
chain postrouting {
type filter hook postrouting priority 100; policy accept;
}
}
#格式2：
#!/usr/sbin/nft -f
define ntp_servers = { 84.77.40.132, 176.31.53.99, 81.19.96.148, 138.100.62.8 }
add table filter
add chain filter input { type filter hook input priority 0; }
add rule filter input ip saddr $ntp_servers counter
脚本例子：
flush ruleset
table t_firewall {
chain c_incoming {
type filter hook input priority 0; policy drop;
# established/related connections
ct state established,related accept
# loopback interface
iifname lo accept
# icmp
icmp type echo-request accept
# open tcp ports: sshd (22), httpd (80)
tcp dport {ssh, http} accept
}
}
table ip6 t_firewall6 {
chain c_incoming {
type filter hook input priority 0; policy drop;
# established/related connections
ct state established,related accept
# invalid connections
ct state invalid drop
# loopback interface
iifname lo accept
# icmp
# routers may also want: mld-listener-query, nd-router-solicit
icmpv6 type {echo-request,nd-neighbor-solicit} accept
# open tcp ports: sshd (22), httpd (80)
tcp dport {ssh, http} accept
}
}
上面保存位文件，使用命令：ntf -f ruleSet.rs 来生效
matches: (摘录自：https://wiki.nftables.org/wiki-nftables/index.php/Quick_reference-nftables_in_10_minutes，更详细内容看这个链接吧)
格式：
obj value
obj operator value # 例如!=，<=
obj value1-value2
obj != value1-value2
obj {value1,value2,value3}
ipv4协议：
ip protocol tcp # 匹配高层协议： icmp, esp, ah, comp, udp, udplite, tcp, dccp, sctp
ip protocol != tcp
ip protocol 6
ipv4数据包长度：
ip length != 333-453
ip length { 333, 553, 673, 838}
ipv4 ttl:
ip ttl 33-55
ip ttl != 45-50
ipv4地址：
ip saddr 192.168.2.0/24
ip saddr != 192.168.2.0/24
ip saddr 192.168.3.1 ip daddr 192.168.3.100
ip saddr != 1.1.1.1
ip saddr 1.1.1.1
ip saddr & 0xff == 1
ip saddr & 0.0.0.255 < 0.0.0.127
ip daddr 192.168.0.1-192.168.0.250
ip daddr { 192.168.0.1-192.168.0.250 }
ip daddr { 192.168.5.1, 192.168.5.2, 192.168.5.3 }
ip版本号：
ip version 4
ct连接状态：
ct state { new, established, related, untracked }
ct state != related
ct state established
ct state 8
ct方向：
ct direction original
ct direction != original
ct direction {reply, original}
ct mark：
ct mark 0
ct mark or 0x23 == 0x11
Meta信息：
meta iifname "eth0"
meta iifname {"eth0", "lo"}
meta iifname "eth*"
meta oifname "eth0"
meta iif eth0
meta oif {eth0, lo}
meta iiftype {ether, ppp, ipip, ipip6, loopback, sit, ipgre}
其他：
ip hdrlength 15
tcp flags != syn
tcp flags & (syn | ack) == syn | ack
icmp type echo-request
ether saddr 00:0f:54:0c:11:04
ether type vlan
vlan id 4094
Statement:
限速：
limit rate 400/minute
limit rate 400/hour
limit rate over 1023/second burst 10 packets
limit rate 1025 kbytes/second
limit rate 1023000 mbytes/second
limit rate 1025 bytes/second burst 512 bytes
limit rate 1025 kbytes/second burst 1023 kbytes
limit rate 1025 mbytes/second burst 1025 kbytes
limit rate 1025000 mbytes/second burst 1023 mbytes
dnat:
dnat 192.168.3.2
dnat ct mark map { 0x00000014 : 1.2.3.4}
snat:
snat 192.168.3.2
snat 2001:838:35f:1::-2001:838:35f:2:::100
masquerade:
masquerade
masquerade persistent,fully-random,random
masquerade to :1024
masquerade to :1024-2048
其他：
reject with icmp type net-prohibited #with <protocol> type <type>
ip protocol tcp reject with tcp reset
log
log level emerg