套接字 – 使用辅助IP地址连接套接字
发布时间：2020-12-14 02:08:28 所属栏目：Linux 来源：网络整理
导读：不久前,我能够通过以下步骤从给定接口上的主要或辅助IP地址连接到给定目标地址. 使用ip addr add …为给定的接口添加辅助IP地址, 根据需要将套接字绑定到主地址或辅助地址, 使用主要或辅助地址连接到目标IP地址,如#2中所示. 我最近将一台机器升级到Linux 3.3
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不久前,我能够通过以下步骤从给定接口上的主要或辅助IP地址连接到给定目标地址.
>使用ip addr add …为给定的接口添加辅助IP地址, 我最近将一台机器升级到Linux 3.3.6,这不再有效,但我不记得我试过的最后一个版本实际上是在工作.有谁知道如何在较新的内核中做同样的事情？我刚刚在另一台机器上验证了2.6.23上的相同代码.
这是当我在3.3.6(在后台运行的tshark的数据包捕获输出)上运行代码(源端)时发生的情况： $./bind_connect 10.0.1.124 10.0.1.120
Bound socket: 10.0.1.120 [10.0.1.120->10.0.1.124]
# wrong source IP (should use 10.0.1.120 from bind)
# |
# v
$121.051052 10.0.1.220 -> 10.0.1.124 50418 80 TCP 74 50418 > 80 [SYN] Seq=3358582895 Win=14600 Len=0 MSS=1460 SACK_PERM=1 TSval=30589624 TSecr=0 WS=128
121.051428 10.0.1.124 -> 10.0.1.220 80 50418 TCP 74 80 > 50418 [SYN,ACK] Seq=1815118993 Ack=3358582896 Win=5792 Len=0 MSS=1460 SACK_PERM=1 TSval=8157158 TSecr=30589624 WS=2
121.051475 10.0.1.220 -> 10.0.1.124 50418 80 TCP 66 50418 > 80 [ACK] Seq=3358582896 Ack=1815118994 Win=14720 Len=0 TSval=30589624 TSecr=8157158
121.051504 10.0.1.220 -> 10.0.1.124 50418 80 TCP 66 50418 > 80 [FIN,ACK] Seq=3358582896 Ack=1815118994 Win=14720 Len=0 TSval=30589624 TSecr=8157158
121.051768 10.0.1.124 -> 10.0.1.220 80 50418 TCP 66 80 > 50418 [ACK] Seq=1815118994 Ack=3358582897 Win=5792 Len=0 TSval=8157158 TSecr=30589624
121.051913 10.0.1.124 -> 10.0.1.220 80 50418 TCP 66 80 > 50418 [FIN,ACK] Seq=1815118994 Ack=3358582897 Win=5792 Len=0 TSval=8157158 TSecr=30589624
121.051941 10.0.1.220 -> 10.0.1.124 50418 80 TCP 66 50418 > 80 [ACK] Seq=3358582897 Ack=1815118995 Win=14720 Len=0 TSval=30589625 TSecr=8157158
$./bind_connect 10.0.1.124 10.0.1.220
Bound socket: 10.0.1.220 [10.0.1.220->10.0.1.124]
$124.139966 10.0.1.220 -> 10.0.1.124 41470 80 TCP 74 41470 > 80 [SYN] Seq=1404133303 Win=14600 Len=0 MSS=1460 SACK_PERM=1 TSval=30590551 TSecr=0 WS=128
124.140421 10.0.1.124 -> 10.0.1.220 80 41470 TCP 74 80 > 41470 [SYN,ACK] Seq=1918490481 Ack=1404133304 Win=5792 Len=0 MSS=1460 SACK_PERM=1 TSval=8157467 TSecr=30590551 WS=2
124.140478 10.0.1.220 -> 10.0.1.124 41470 80 TCP 66 41470 > 80 [ACK] Seq=1404133304 Ack=1918490482 Win=14720 Len=0 TSval=30590551 TSecr=8157467
124.140553 10.0.1.220 -> 10.0.1.124 41470 80 TCP 66 41470 > 80 [FIN,ACK] Seq=1404133304 Ack=1918490482 Win=14720 Len=0 TSval=30590551 TSecr=8157467
124.140934 10.0.1.124 -> 10.0.1.220 80 41470 TCP 66 80 > 41470 [ACK] Seq=1918490482 Ack=1404133305 Win=5792 Len=0 TSval=8157467 TSecr=30590551
124.140976 10.0.1.124 -> 10.0.1.220 80 41470 TCP 66 80 > 41470 [FIN,ACK] Seq=1918490482 Ack=1404133305 Win=5792 Len=0 TSval=8157467 TSecr=30590551
124.140995 10.0.1.220 -> 10.0.1.124 41470 80 TCP 66 41470 > 80 [ACK] Seq=1404133305 Ack=1918490483 Win=14720 Len=0 TSval=30590551 TSecr=8157467
$uname -a
Linux erebus.mn.ca 3.3.6-1-ARCH #1 SMP PREEMPT Sun May 13 09:59:18 UTC 2012 i686 GNU/Linux
$ip route get 10.0.1.124
10.0.1.124 dev eth0.894 src 10.0.1.220
cache ipid 0x61ca rtt 3ms rttvar 3ms cwnd 10
然后在2.6.23上相同： $./bind_connect 10.0.0.123 10.0.0.226 >
Bound socket: 10.0.0.226 [10.0.0.226->10.0.0.123]
$231.566278 10.0.0.226 -> 10.0.0.123 TCP 54109 > http [SYN] Seq=0 Win=5840 Len=0 MSS=1460 TSV=99922052 TSER=0 WS=5
231.566448 10.0.0.123 -> 10.0.0.226 TCP http > 54109 [SYN,ACK] Seq=0 Ack=1 Win=5792 Len=0 MSS=1460 TSV=7060755 TSER=99922052 WS=1
231.566463 10.0.0.226 -> 10.0.0.123 TCP 54109 > http [ACK] Seq=1 Ack=1 Win=5856 Len=0 TSV=99922052 TSER=7060755
231.566510 10.0.0.226 -> 10.0.0.123 TCP 54109 > http [FIN,ACK] Seq=1 Ack=1 Win=5856 Len=0 TSV=99922052 TSER=7060755
231.566593 10.0.0.123 -> 10.0.0.226 TCP http > 54109 [ACK] Seq=1 Ack=2 Win=5792 Len=0 TSV=7060755 TSER=99922052
231.566704 10.0.0.123 -> 10.0.0.226 TCP http > 54109 [FIN,ACK] Seq=1 Ack=2 Win=5792 Len=0 TSV=7060755 TSER=99922052
231.566737 10.0.0.226 -> 10.0.0.123 TCP 54109 > http [ACK] Seq=2 Ack=2 Win=5856 Len=0 TSV=99922052 TSER=7060755
$./bind_connect 10.0.0.123 10.0.0.126 >
Bound socket: 10.0.0.126 [10.0.0.126->10.0.0.123]
$235.824867 10.0.0.126 -> 10.0.0.123 TCP 34228 > http [SYN] Seq=0 Win=5840 Len=0 MSS=1460 TSV=99926310 TSER=0 WS=5
235.825185 10.0.0.123 -> 10.0.0.126 TCP http > 34228 [SYN,ACK] Seq=0 Ack=1 Win=5792 Len=0 MSS=1460 TSV=7061180 TSER=99926310 WS=1
235.825236 10.0.0.126 -> 10.0.0.123 TCP 34228 > http [ACK] Seq=1 Ack=1 Win=5856 Len=0 TSV=99926311 TSER=7061180
235.825273 10.0.0.126 -> 10.0.0.123 TCP 34228 > http [FIN,ACK] Seq=1 Ack=1 Win=5856 Len=0 TSV=99926311 TSER=7061180
235.825721 10.0.0.123 -> 10.0.0.126 TCP http > 34228 [ACK] Seq=1 Ack=2 Win=5792 Len=0 TSV=7061180 TSER=99926311
235.825722 10.0.0.123 -> 10.0.0.126 TCP http > 34228 [FIN,ACK] Seq=1 Ack=2 Win=5792 Len=0 TSV=7061180 TSER=99926311
235.825756 10.0.0.126 -> 10.0.0.123 TCP 34228 > http [ACK] Seq=2 Ack=2 Win=5856 Len=0 TSV=99926311 TSER=7061180
$uname -a
Linux gaia.mn.ca 2.6.23.17-88.fc7 #1 SMP Thu May 15 00:35:10 EDT 2008 i686 i686 i386 GNU/Linux
$ip route get 10.0.0.123
10.0.0.123 dev eth0 src 10.0.0.126
cache mtu 1500 advmss 1460 hoplimit 64
bind_connect的代码： #include <arpa/inet.h>
#include <errno.h>
#include <netinet/in.h>
#include <netinet/tcp.h>
#include <stdio.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <unistd.h>
int main(int argc,char **argv)
{
struct sockaddr_in sn;
socklen_t sn_len;
struct sockaddr_in src;
struct sockaddr_in dst;
int sock;
char b1[INET_ADDRSTRLEN];
char b2[INET_ADDRSTRLEN];
char b3[INET_ADDRSTRLEN];
src.sin_family = dst.sin_family = AF_INET;
src.sin_port = 0;
dst.sin_port = htons(80);
if (argc < 3) {
printf("missing argumentn");
return 1;
}
if (inet_pton(AF_INET,argv[1],&dst.sin_addr) != 1) {
perror("pton");
return -errno;
}
if (inet_pton(AF_INET,argv[2],&src.sin_addr) != 1) {
perror("pton");
return -errno;
}
sock = socket(AF_INET,SOCK_STREAM,0);
if (sock < 0) {
perror("socket");
return -errno;
}
if (bind(sock,(struct sockaddr*)&src,sizeof src) != 0) {
perror("bind");
return -errno;
}
sn_len = sizeof sn;
if (getsockname(sock,(struct sockaddr*)&sn,&sn_len) != 0) {
perror("getsockname");
return -errno;
}
printf("Bound socket: %s [%s->%s]n",inet_ntop(AF_INET,&sn.sin_addr,b1,sizeof b1),&src.sin_addr,b2,sizeof b2),&dst.sin_addr,b3,sizeof b3));
if (connect(sock,(struct sockaddr*)&dst,sizeof dst) != 0) {
perror("connect");
return -errno;
}
close(sock);
return 0;
}
解决方法
问题是我用iptables建立了一个nat POSTROUTING规则,即
Chain POSTROUTING (policy ACCEPT 11 packets,637 bytes)
pkts bytes target prot opt in out source destination
0 0 MASQUERADE all -- any eth0.894 anywhere anywhere
删除此规则后： $sudo iptables -t nat -F 事情又开始起作用了.我刚刚在测试另一个问题时设置了nat规则,然后忘了将其删除. （编辑：李大同） 【声明】本站内容均来自网络，其相关言论仅代表作者个人观点，不代表本站立场。若无意侵犯到您的权利，请及时与联系站长删除相关内容! |
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