conntrack-tools使用

基础用法

系统配置

### 开启流数据包统计（packets和bytes）
# echo "net.netfilter.nf_conntrack_acct=1" >> /etc/sysctl.conf
### 开启流持续时间统计（delta-time）
# echo "net.netfilter.nf_conntrack_timestamp=1" >> /etc/sysctl.conf
# sysctl -p /etc/sysctl.conf

命令使用

• 显示当前正在被追踪的流

# conntrack -L -o ktimestamp
tcp      6 431666 ESTABLISHED src=10.0.0.2 dst=20.0.0.6 sport=33715 dport=22 packets=17 bytes=2094 src=20.0.0.6 dst=10.0.0.2 sport=22 dport=33715 packets=14 bytes=1870 [ASSURED] mark=0 zone=1 delta-time=336 [start=Wed Sep 13 15:48:40 2017] use=1
icmp     1 29 src=20.0.0.11 dst=20.0.0.6 type=8 code=0 id=40449 packets=5 bytes=420 src=20.0.0.6 dst=20.0.0.11 type=0 code=0 id=40449 packets=5 bytes=420 mark=0 zone=9 delta-time=4 [start=Wed Sep 13 15:55:46 2017] use=1

• 监控流事件

# conntrack -E -o ktimestamp
[NEW] tcp      6 120 SYN_SENT src=10.0.0.2 dst=20.0.0.6 sport=33717 dport=22 [UNREPLIED] src=20.0.0.6 dst=10.0.0.2 sport=22 dport=33717 zone=1
[DESTROY] tcp      6 src=10.0.0.2 dst=20.0.0.6 sport=33717 dport=22 packets=31 bytes=3042 src=20.0.0.6 dst=10.0.0.2 sport=22 dport=33717 packets=23 bytes=2666 [ASSURED] zone=1 delta-time=142 [start=Wed Sep 13 16:07:06 2017] [stop=Wed Sep 13 16:09:28 2017]

高级用法

-L命令实现

# vim main.c
#include <stdio.h>
#include <assert.h>
#include <libmnl/libmnl.h>
#include <libnetfilter_conntrack/libnetfilter_conntrack.h>

static int dump_cb(enum nf_conntrack_msg_type type, struct nf_conntrack *ct, void *data)
{
  char buf[1024];
  unsigned int op_type = NFCT_O_DEFAULT;
  unsigned int op_flags = 0;
  nfct_snprintf(buf, sizeof(buf), ct, NFCT_T_UNKNOWN, op_type, op_flags);
  printf("%s\n", buf);
  return NFCT_CB_CONTINUE;
}

int main()
{
  struct nfct_handle *cth = nfct_open(CONNTRACK, 0);
  assert(cth != NULL);

  nfct_callback_register(cth, NFCT_T_ALL, dump_cb, NULL);
  struct nfct_filter_dump *filter_dump = nfct_filter_dump_create();
  assert(filter_dump != NULL);

  nfct_filter_dump_set_attr_u8(filter_dump, NFCT_FILTER_DUMP_L3NUM, AF_INET);
  nfct_query(cth, NFCT_Q_DUMP_FILTER, filter_dump);
  printf("============测试一下=================\n");
  nfct_query(cth, NFCT_Q_DUMP_FILTER, filter_dump);
  nfct_filter_dump_destroy(filter_dump);
  nfct_close(cth);
}

# yum install -y libnetfilter_conntrack-devel libmnl-devel
# gcc main.c -lnetfilter_conntrack -lmnl -o ct

问题处理

在容器中运行conntrack命令报错

conntrack v1.4.4 (conntrack-tools): Operation failed: sorry, you must be root or get CAP_NET_ADMIN capability to do this

### 解决办法，容器运行需要添加如下参数

# docker run --privileged=true --net=host

参考资料

conntrack
iptables-tutorial
netfilter官网