Hi list, I have a firewall with 4 NIC: - 3 interfaces connected to the net (eth2, eth3, eth5) by 3 ISP; - 1 interface connected to the internal network. eth2 is connected to a router (10.0.1.1) which does masquerading. Outcoming request (from the internal network to the net) are load balanced to the 3 ISP (cf my configuration at the end of the mail). All incoming request from the net to internal network by port http, pop3, imap, ftp, smtp, https are correctly routed. All outcoming request from the internal network to the net by port http, pop3, imap are correctly routed. The problem is that I can't connect from the internal network to a ftp server of the net. In fact, I can connect to a ftp server of the net but the "ls" command failed the most of the time (1/3). I use passive mode. Can you help me please ? Thanks in advance If I add the route by the command ip route add <@ftpServer> via <@GATEWAY_ISP2> it is OK Here is my configuration (long but complete... I hope): ============================================================= Routing table and rules ============================================================= [root@firewall firewall]# ip ru l 0: from all lookup local 32763: from all fwmark 3 lookup 212 32764: from all fwmark 2 lookup 211 32765: from all fwmark 1 lookup 210 32766: from all lookup main 32767: from all lookup 253 -------------------------------------------------------------- [root@firewall firewall]# ip route list <@NETMASK_ISP2>/30 dev eth5 proto kernel scope link src <@ISP2> 10.0.3.0/30 dev eth5 scope link 10.0.1.0/24 dev eth2 scope link 10.1.0.0/24 dev eth0 scope link <@NETMASK_ISP3>/24 dev eth3 scope link 127.0.0.0/8 dev lo scope link default nexthop via 10.0.1.1 dev eth2 weight 1 onlink nexthop via <@GATEWAY_ISP2> dev eth5 weight 1 onlink nexthop via <@GATEWAY_ISP3> dev eth3 weight 1 onlink -------------------------------------------------------------- [root@firewall firewall]# ip ro l t 210 <@NETMASK_ISP2>/30 dev eth5 proto kernel scope link src <@ISP2> 10.0.3.0/30 dev eth5 scope link 10.0.1.0/24 dev eth2 scope link 10.1.0.0/24 dev eth0 scope link <@NETMASK_ISP3>/24 dev eth3 scope link 127.0.0.0/8 dev lo scope link default via 10.0.1.1 dev eth2 --------------------------------------------------------------- [root@firewall firewall]# ip ro l t 211 <@NETMASK_ISP2>/30 dev eth5 proto kernel scope link src <@ISP2> 10.0.3.0/30 dev eth5 scope link 10.0.1.0/24 dev eth2 scope link 10.1.0.0/24 dev eth0 scope link <@NETMASK_ISP3>/24 dev eth3 scope link 127.0.0.0/8 dev lo scope link default via <@GATEWAY_ISP3> dev eth3 ----------------------------------------------------------------- [root@firewall firewall]# ip ro l t 212 <@NETMASK_ISP2>/30 dev eth5 proto kernel scope link src <@ISP2> 10.0.3.0/30 dev eth5 scope link 10.0.1.0/24 dev eth2 scope link 10.1.0.0/24 dev eth0 scope link <@NETMASK_ISP3>/24 dev eth3 scope link 127.0.0.0/8 dev lo scope link default via <@GATEWAY_ISP2> dev eth5 ================================================================== IPTABLES tables ================================================================== [root@firewall firewall]# iptables -L -v -n -t nat Chain PREROUTING (policy ACCEPT 531K packets, 34M bytes) pkts bytes target prot opt in out source destination 4496 293K net_dnat all -- eth2 * 0.0.0.0/0 0.0.0.0/0 39294 1956K net_dnat all -- eth3 * 0.0.0.0/0 0.0.0.0/0 18601 1158K net_dnat all -- eth5 * 0.0.0.0/0 0.0.0.0/0 Chain POSTROUTING (policy ACCEPT 81932 packets, 4985K bytes) pkts bytes target prot opt in out source destination 182K 9122K eth3_masq all -- * eth3 0.0.0.0/0 0.0.0.0/0 166K 8193K eth5_masq all -- * eth5 0.0.0.0/0 0.0.0.0/0 Chain OUTPUT (policy ACCEPT 32386 packets, 2508K bytes) pkts bytes target prot opt in out source destination Chain eth3_masq (1 references) pkts bytes target prot opt in out source destination 159K 7823K MASQUERADE all -- * * 10.1.0.0/24 0.0.0.0/0 Chain eth5_masq (1 references) pkts bytes target prot opt in out source destination 159K 7825K MASQUERADE all -- * * 10.1.0.0/24 0.0.0.0/0 Chain net_dnat (3 references) (...) ---------------------------------------------------------------- [root@firewall firewall]# iptables -L -v -n -t mangle Chain PREROUTING (policy ACCEPT 4008K packets, 1940M bytes) pkts bytes target prot opt in out source destination 2223 168K MARK tcp -- * * 0.0.0.0/0 0.0.0.0/0 tcp spt:21 MARK set 0x1 9364 3221K MARK tcp -- * * 0.0.0.0/0 0.0.0.0/0 tcp spt:20 MARK set 0x1 0 0 MARK udp -- * * 0.0.0.0/0 0.0.0.0/0 udp spt:21 MARK set 0x1 0 0 MARK udp -- * * 0.0.0.0/0 0.0.0.0/0 udp spt:20 MARK set 0x1 14916 1413K MARK all -- * * 0.0.0.0/0 0.0.0.0/0 ctorigdst <@ISP2> MARK set 0x3 72454 17M MARK all -- * * 0.0.0.0/0 0.0.0.0/0 ctorigdst <@ISP3> MARK set 0x2 94175 43M MARK all -- * * 0.0.0.0/0 0.0.0.0/0 ctorigdst 10.0.1.10 MARK set 0x1 4008K 1940M pretos all -- * * 0.0.0.0/0 0.0.0.0/0 1282 108K MARK all -- * * 0.0.0.0/0 0.0.0.0/0 ctorigsrc <@ISP2> MARK set 0x3 1327 112K MARK all -- * * 0.0.0.0/0 0.0.0.0/0 ctorigsrc <@ISP3> MARK set 0x2 65220 41M MARK all -- * * 0.0.0.0/0 0.0.0.0/0 ctorigsrc 10.1.0.10 MARK set 0x1 Chain INPUT (policy ACCEPT 154K packets, 16M bytes) pkts bytes target prot opt in out source destination Chain FORWARD (policy ACCEPT 3828K packets, 1923M bytes) pkts bytes target prot opt in out source destination Chain OUTPUT (policy ACCEPT 86903 packets, 5978K bytes) pkts bytes target prot opt in out source destination 7587 402K MARK all -- * * <@ISP2> 0.0.0.0/0 MARK set 0x3 24567 1440K MARK all -- * * <@ISP3> 0.0.0.0/0 MARK set 0x2 5332 418K MARK all -- * * 10.0.1.10 0.0.0.0/0 MARK set 0x1 86903 5978K outtos all -- * * 0.0.0.0/0 0.0.0.0/0 Chain POSTROUTING (policy ACCEPT 3890K packets, 1927M bytes) pkts bytes target prot opt in out source destination Chain outtos (1 references) pkts bytes target prot opt in out source destination 712 61690 TOS tcp -- * * 0.0.0.0/0 0.0.0.0/0 tcp dpt:22 TOS set 0x10 2708 438K TOS tcp -- * * 0.0.0.0/0 0.0.0.0/0 tcp spt:22 TOS set 0x10 8 320 TOS tcp -- * * 0.0.0.0/0 0.0.0.0/0 tcp dpt:21 TOS set 0x10 0 0 TOS tcp -- * * 0.0.0.0/0 0.0.0.0/0 tcp spt:21 TOS set 0x10 0 0 TOS tcp -- * * 0.0.0.0/0 0.0.0.0/0 tcp spt:20 TOS set 0x08 0 0 TOS tcp -- * * 0.0.0.0/0 0.0.0.0/0 tcp dpt:20 TOS set 0x08 Chain pretos (1 references) pkts bytes target prot opt in out source destination 22272 1209K TOS tcp -- * * 0.0.0.0/0 0.0.0.0/0 tcp dpt:22 TOS set 0x10 19801 8705K TOS tcp -- * * 0.0.0.0/0 0.0.0.0/0 tcp spt:22 TOS set 0x10 2140 112K TOS tcp -- * * 0.0.0.0/0 0.0.0.0/0 tcp dpt:21 TOS set 0x10 2223 168K TOS tcp -- * * 0.0.0.0/0 0.0.0.0/0 tcp spt:21 TOS set 0x10 9364 3221K TOS tcp -- * * 0.0.0.0/0 0.0.0.0/0 tcp spt:20 TOS set 0x08 8865 7140K TOS tcp -- * * 0.0.0.0/0 0.0.0.0/0 tcp dpt:20 TOS set 0x08 =============================================================== LOADED MODULES =============================================================== [root@firewall firewall]# lsmod Module Size Used by Not tainted nls_iso8859-15 4060 0 (autoclean) isofs 28856 0 (autoclean) zlib_inflate 21764 0 (autoclean) [isofs] vfat 12204 0 (autoclean) fat 38072 0 (autoclean) [vfat] ide-cd 33860 0 (autoclean) cdrom 32736 0 (autoclean) [ide-cd] ipt_MARK 1336 13 (autoclean) ipt_conntrack 1528 6 (autoclean) ipt_TOS 1592 12 (autoclean) ipt_MASQUERADE 2200 20 (autoclean) ipt_LOG 4312 11 (autoclean) ipt_REJECT 3768 4 (autoclean) ipt_state 1048 71 (autoclean) iptable_mangle 2712 1 (autoclean) ip_nat_irc 3472 0 (unused) ip_nat_ftp 4240 0 (unused) iptable_nat 21894 3 [ipt_MASQUERADE ip_nat_irc ip_nat_ftp] ip_conntrack_irc 4400 1 [ip_nat_irc] ip_conntrack_ftp 5424 1 [ip_nat_ftp] ip_conntrack 28864 5 [ipt_conntrack ipt_MASQUERADE ipt_state ip_nat_irc ip_nat_ftp iptable_nat ip_conntrack_irc ip_conntrack_ftp] iptable_filter 2348 1 (autoclean) ip_tables 15424 12 [ipt_MARK ipt_conntrack ipt_TOS ipt_MASQUERADE ipt_LOG ipt_REJECT ipt_state iptable_mangle iptable_nat iptable_filter] af_packet 16328 1 (autoclean) sundance 16224 3 (autoclean) eepro100 22228 2 (autoclean) mii 3980 0 (autoclean) [sundance eepro100] usb-uhci 26128 0 (unused) usbcore 77324 1 [usb-uhci] rtc 8776 0 (autoclean) reiserfs 183540 5