我正在为我的服务器开发防火墙脚本。到目前为止，除了 FTP 之外，它运行良好。服务器是专用的，基于 CentOS，具有静态 IP。我和服务器之间没有 NAT。IPTables 是防火墙。
下面是我用来配置 iptables 的脚本： http://pastebin.com/f54a70fec
我允许其中的所有 RELATED 和 ESTABLISHED 连接并加载所有 conn_track 模块。我认为这足以让 FTP 与 iptables 协同工作。
问题是 FTP 无法在被动或主动模式下工作。FileZilla 和 TotalCommander 只是挂在 MLSD FTP 命令上。在 FTP 连接的确切时刻，服务器日志中有一些奇怪的数据包被防火墙丢弃：
Dec 20 15:37:09 server ntpd[12329]: synchronized to 81.200.8.213, stratum 5
Dec 20 15:37:14 server proftpd[30526]: gsmforum.ru (::ffff:95.24.7.25[::ffff:95.24.7.25]) - FTP session opened.
Dec 20 12:37:14 server proftpd[30526]: gsmforum.ru (::ffff:95.24.7.25[::ffff:95.24.7.25]) - Preparing to chroot to directory '/home/gsmforum'
Dec 20 15:37:23 server kernel: {fw}UNKNOWN:IN=eth0 OUT= MAC=ff:ff:ff:ff:ff:ff:00:1a:64:6b:1d:67:08:00 SRC=0.0.0.0 DST=255.255.255.255 LEN=306 TOS=0x00 PREC=0x00 TTL=128 ID=32566 DF PROTO=UDP SPT=68 DPT=67 LEN=286
Dec 20 15:37:25 server kernel: {fw}UNKNOWN:IN=eth0 OUT= MAC=ff:ff:ff:ff:ff:ff:00:1f:29:63:03:de:08:00 SRC=89.111.189.17 DST=255.255.255.255 LEN=68 TOS=0x00 PREC=0x00 TTL=128 ID=13480 PROTO=UDP SPT=1052 DPT=1947 LEN=48
Dec 20 15:37:26 server kernel: {fw}UNKNOWN:IN=eth0 OUT= MAC=00:15:17:62:db:28:00:1f:26:27:34:c2:08:00 SRC=81.169.231.108 DST=79.174.68.223 LEN=40 TOS=0x00 PREC=0x00 TTL=53 ID=61798 PROTO=TCP SPT=4178 DPT=80 WINDOW=65535 RES=0x00 ACK FIN URGP=0
Dec 20 15:37:26 server kernel: {fw}UNKNOWN:IN=eth0 OUT= MAC=ff:ff:ff:ff:ff:ff:00:1a:64:9c:50:e7:08:00 SRC=0.0.0.0 DST=255.255.255.255 LEN=306 TOS=0x00 PREC=0x00 TTL=128 ID=50015 DF PROTO=UDP SPT=68 DPT=67 LEN=286
Dec 20 15:37:26 server kernel: {fw}UNKNOWN:IN=eth0 OUT= MAC=00:15:17:62:db:28:00:1f:26:27:34:c2:08:00 SRC=81.169.231.108 DST=79.174.68.223 LEN=40 TOS=0x00 PREC=0x00 TTL=53 ID=62305 PROTO=TCP SPT=4178 DPT=80 WINDOW=65535 RES=0x00 ACK FIN URGP=0
Dec 20 15:37:26 server kernel: {fw}UNKNOWN:IN=eth0 OUT= MAC=ff:ff:ff:ff:ff:ff:00:19:bb:eb:c6:e1:08:00 SRC=0.0.0.0 DST=255.255.255.255 LEN=328 TOS=0x00 PREC=0x00 TTL=30 ID=5245 PROTO=UDP SPT=68 DPT=67 LEN=308
Dec 20 15:37:27 server kernel: {fw}UNKNOWN:IN=eth0 OUT= MAC=00:15:17:62:db:28:00:1f:26:27:34:c2:08:00 SRC=81.169.231.108 DST=79.174.68.223 LEN=40 TOS=0x00 PREC=0x00 TTL=53 ID=63285 PROTO=TCP SPT=4178 DPT=80 WINDOW=65535 RES=0x00 ACK FIN URGP=0
Dec 20 15:37:29 server kernel: {fw}UNKNOWN:IN=eth0 OUT= MAC=00:15:17:62:db:28:00:1f:26:27:34:c2:08:00 SRC=81.169.231.108 DST=79.174.68.223 LEN=40 TOS=0x00 PREC=0x00 TTL=53 ID=391 PROTO=TCP SPT=4183 DPT=80 WINDOW=65535 RES=0x00 ACK FIN URGP=0
Dec 20 15:37:29 server kernel: {fw}UNKNOWN:IN=eth0 OUT= MAC=00:15:17:62:db:28:00:1f:26:27:34:c2:08:00 SRC=81.169.231.108 DST=79.174.68.223 LEN=40 TOS=0x00 PREC=0x00 TTL=53 ID=707 PROTO=TCP SPT=4178 DPT=80 WINDOW=65535 RES=0x00 ACK FIN URGP=0
Dec 20 15:37:30 server kernel: {fw}UNKNOWN:IN=eth0 OUT= MAC=00:15:17:62:db:28:00:1f:26:27:34:c2:08:00 SRC=81.169.231.108 DST=79.174.68.223 LEN=40 TOS=0x00 PREC=0x00 TTL=53 ID=975 PROTO=TCP SPT=4183 DPT=80 WINDOW=65535 RES=0x00 ACK FIN URGP=0
Dec 20 15:37:30 server kernel: {fw}UNKNOWN:IN=eth0 OUT= MAC=ff:ff:ff:ff:ff:ff:00:15:17:10:c5:9b:08:00 SRC=0.0.0.0 DST=255.255.255.255 LEN=328 TOS=0x00 PREC=0x00 TTL=30 ID=28799 PROTO=UDP SPT=68 DPT=67 LEN=308
Dec 20 15:37:30 server kernel: {fw}UNKNOWN:IN=eth0 OUT= MAC=00:15:17:62:db:28:00:1f:26:27:34:c2:08:00 SRC=81.169.231.108 DST=79.174.68.223 LEN=40 TOS=0x00 PREC=0x00 TTL=53 ID=2020 PROTO=TCP SPT=4187 DPT=80 WINDOW=65535 RES=0x00 ACK FIN URGP=0
Dec 20 15:37:31 server kernel: {fw}UNKNOWN:IN=eth0 OUT= MAC=00:15:17:62:db:28:00:1f:26:27:34:c2:08:00 SRC=81.169.231.108 DST=79.174.68.223 LEN=40 TOS=0x00 PREC=0x00 TTL=53 ID=2383 PROTO=TCP SPT=4183 DPT=80 WINDOW=65535 RES=0x00 ACK FIN URGP=0
Dec 20 15:37:31 server kernel: {fw}UNKNOWN:IN=eth0 OUT= MAC=00:15:17:62:db:28:00:1f:26:27:34:c2:08:00 SRC=81.169.231.108 DST=79.174.68.223 LEN=40 TOS=0x00 PREC=0x00 TTL=53 ID=2533 PROTO=TCP SPT=4187 DPT=80 WINDOW=65535 RES=0x00 ACK FIN URGP=0
Dec 20 15:37:32 server kernel: {fw}UNKNOWN:IN=eth0 OUT= MAC=00:15:17:62:db:28:00:1f:26:27:34:c2:08:00 SRC=81.169.231.108 DST=79.174.68.223 LEN=40 TOS=0x00 PREC=0x00 TTL=53 ID=3271 PROTO=TCP SPT=4190 DPT=80 WINDOW=65535 RES=0x00 ACK FIN URGP=0
Dec 20 15:37:32 server kernel: {fw}UNKNOWN:IN=eth0 OUT= MAC=00:15:17:62:db:28:00:1f:26:27:34:c2:08:00 SRC=77.35.184.49 DST=79.174.68.223 LEN=40 TOS=0x00 PREC=0x00 TTL=115 ID=14501 DF PROTO=TCP SPT=1355 DPT=80 WINDOW=65535 RES=0x00 ACK FIN URGP=0
Dec 20 15:37:32 server kernel: {fw}UNKNOWN:IN=eth0 OUT= MAC=00:15:17:62:db:28:00:1f:26:27:34:c2:08:00 SRC=81.169.231.108 DST=79.174.68.223 LEN=40 TOS=0x00 PREC=0x00 TTL=53 ID=3700 PROTO=TCP SPT=4187 DPT=80 WINDOW=65535 RES=0x00 ACK FIN URGP=0
Dec 20 15:37:32 server kernel: {fw}UNKNOWN:IN=eth0 OUT= MAC=00:15:17:62:db:28:00:1f:26:27:34:c2:08:00 SRC=81.169.231.108 DST=79.174.68.223 LEN=40 TOS=0x00 PREC=0x00 TTL=53 ID=3769 PROTO=TCP SPT=4196 DPT=80 WINDOW=65535 RES=0x00 ACK FIN URGP=0
Dec 20 15:37:32 server kernel: {fw}UNKNOWN:IN=eth0 OUT= MAC=00:15:17:62:db:28:00:1f:26:27:34:c2:08:00 SRC=81.169.231.108 DST=79.174.68.223 LEN=40 TOS=0x00 PREC=0x00 TTL=53 ID=4034 PROTO=TCP SPT=4190 DPT=80 WINDOW=65535 RES=0x00 ACK FIN URGP=0
Dec 20 15:37:33 server kernel: {fw}UNKNOWN:IN=eth0 OUT= MAC=00:15:17:62:db:28:00:1f:26:27:34:c2:08:00 SRC=81.169.231.108 DST=79.174.68.223 LEN=40 TOS=0x00 PREC=0x00 TTL=53 ID=4522 PROTO=TCP SPT=4196 DPT=80 WINDOW=65535 RES=0x00 ACK FIN URGP=0
Dec 20 15:37:33 server kernel: {fw}UNKNOWN:IN=eth0 OUT= MAC=00:15:17:62:db:28:00:1f:26:27:34:c2:08:00 SRC=81.169.231.108 DST=79.174.68.223 LEN=40 TOS=0x00 PREC=0x00 TTL=53 ID=4657 PROTO=TCP SPT=4183 DPT=80 WINDOW=65535 RES=0x00 ACK FIN URGP=0
你能告诉我问题出在哪里吗？除了这个该死的 FTP，一切都运行正常。
答案1
解决方案是添加
MasqueradeAddress example.com
PassivePorts 65400 65534
到 /etc/proftpd.conf 并配置 iptables：
#FTP server(21)
iptables -A INPUT -p tcp -m tcp -i $FR_INET_IFACE --dport 21 -j ACCEPT #Main FTP port
iptables -A OUTPUT -p tcp -m tcp -o $FR_INET_IFACE --sport 20 -j ACCEPT #Active FTP port
iptables -A INPUT -p tcp -m tcp -i $FR_INET_IFACE --dport 65400:65534 -j ACCEPT #Passive FTP