TL;DR - 我正在寻找一种方法，通过代理服务器发送所有外部流量，但不通过代理服务器发送所有内部流量。我该如何实现这一点？
我的最终目标是将所有外部流量从 phantomjs 节点转发到互联网上的一组代理服务器，并阻止所有发往我的一台服务器（10.X.1.X）的流量到达外部代理服务器。
据我所知，我需要使用透明代理。我尝试过使用 HAProxy 和 IPFire，但没有成功。
我的下一次尝试是使用 IPTables。我在虚拟机上的 CentOS 6.8 上使用 IPTables v1.4.7。IP 地址是 10.2.1.234。我已成功设置 IPTables，使用以下 IPTables 规则将所有流量轮询到互联网上的 5 个代理服务器：
Table: nat
Chain PREROUTING (policy ACCEPT)
num target prot opt source destination
1 DNAT tcp -- 0.0.0.0/0 0.0.0.0/0 statistic mode nth every 5 tcp dpt:80 to:104.36.80.240:80
2 DNAT tcp -- 0.0.0.0/0 0.0.0.0/0 statistic mode nth every 4 tcp dpt:80 to:104.36.81.104:80
3 DNAT tcp -- 0.0.0.0/0 0.0.0.0/0 statistic mode nth every 3 tcp dpt:80 to:104.36.81.12:80
4 DNAT tcp -- 0.0.0.0/0 0.0.0.0/0 statistic mode nth every 2 tcp dpt:80 to:104.36.82.153:80
5 DNAT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:80 to:104.36.80.241:80
Chain POSTROUTING (policy ACCEPT)
num target prot opt source destination
1 MASQUERADE all -- 0.0.0.0/0 0.0.0.0/0
Chain OUTPUT (policy ACCEPT)
num target prot opt source destination
Table: filter
Chain INPUT (policy ACCEPT)
num target prot opt source destination
1 ACCEPT all -- 0.0.0.0/0 0.0.0.0/0 state RELATED,ESTABLISHED
2 ACCEPT icmp -- 0.0.0.0/0 0.0.0.0/0
3 ACCEPT all -- 0.0.0.0/0 0.0.0.0/0
4 ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 state NEW tcp dpt:22
5 ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:80
Chain FORWARD (policy ACCEPT)
num target prot opt source destination
Chain OUTPUT (policy ACCEPT)
num target prot opt source destination
我在 /etc/sysctl.conf 中设置了以下内容
# Controls IP packet forwarding
net.ipv4.ip_forward = 1
/etc/sysconfig/iptables 配置
# Load additional iptables modules (nat helpers)
# Default: -none-
# Space separated list of nat helpers (e.g. 'ip_nat_ftp ip_nat_irc'), which
# are loaded after the firewall rules are applied. Options for the helpers are
# stored in /etc/modprobe.conf.
IPTABLES_MODULES=""
# Unload modules on restart and stop
# Value: yes|no, default: yes
# This option has to be 'yes' to get to a sane state for a firewall
# restart or stop. Only set to 'no' if there are problems unloading netfilter
# modules.
IPTABLES_MODULES_UNLOAD="yes"
# Save current firewall rules on stop.
# Value: yes|no, default: no
# Saves all firewall rules to /etc/sysconfig/iptables if firewall gets stopped
# (e.g. on system shutdown).
IPTABLES_SAVE_ON_STOP="yes"
# Save current firewall rules on restart.
# Value: yes|no, default: no
# Saves all firewall rules to /etc/sysconfig/iptables if firewall gets
# restarted.
IPTABLES_SAVE_ON_RESTART="yes"
# Save (and restore) rule and chain counter.
# Value: yes|no, default: no
# Save counters for rules and chains to /etc/sysconfig/iptables if
# 'service iptables save' is called or on stop or restart if SAVE_ON_STOP or
# SAVE_ON_RESTART is enabled.
IPTABLES_SAVE_COUNTER="no"
# Numeric status output
# Value: yes|no, default: yes
# Print IP addresses and port numbers in numeric format in the status output.
IPTABLES_STATUS_NUMERIC="yes"
# Verbose status output
# Value: yes|no, default: yes
# Print info about the number of packets and bytes plus the "input-" and
# "outputdevice" in the status output.
IPTABLES_STATUS_VERBOSE="no"
# Status output with numbered lines
# Value: yes|no, default: yes
# Print a counter/number for every rule in the status output.
IPTABLES_STATUS_LINENUMBERS="yes"
# Reload sysctl settings on start and restart
# Default: -none-
# Space separated list of sysctl items which are to be reloaded on start.
# List items will be matched by fgrep.
#IPTABLES_SYSCTL_LOAD_LIST=".nf_conntrack .bridge-nf"
/proc/sys/net/ipv4/ip_forward
1
我的问题是当我尝试免除将本地地址发送到外部代理服务器时。我认为 ACCEPT 可能会起作用，并将以下内容添加到 nat PREROUTING 表中：
1 ACCEPT tcp -- 0.0.0.0/0 10.1.1.0/24
然后我从我的桌面发送以下 curl 命令，但它没有触发该规则！它触发了其中一条循环规则。
curl -v -k -x 10.2.1.234:80 http://10.1.1.228/
我尝试使用 DNAT 和 FORWARD 进行类似操作，但无论出于什么原因，IPTables 都不尊重目标地址。我是不是漏掉了什么？