Help with an iptables problem (maybe SNAT?)

Dave Herrald dave@fropa.com
Mon, 3 Dec 2001 11:49:12 -0700 (MST)


Hi all.  First off, sorry for the long post, just trying to be thorough.

I recently inherited a network that uses an iptables firewall.  Last week
I began experiencing a problem using SNAT to allow the internal desktops
to connect to the Internet.  The symptom I have is that HTTP connections
to most web sites hang indefinitely.

Below, I've inlcuded the output from a tcpdump of one of the hanging
transactions.  The client is privately addressed (10.10.21.70) and is
behind the firewall.  The SNAT "to" address is xxx.yyy.zzz.80.  If I'm
interpreting this right, the output shows that the connection begins
normally but after a few packets are received from the server, the server
seems to "start over" re-sending data that has already been acked.
Specifically see lines 20 and 21--the client is acking 4381 and the
server sends 1-1461 again which had been acked earlier in lines 13-14.
Then the two sides go back and forth for a while but no more data is
ever transferred.

If I put a laptop outside the firewall and give it a routable address I
can access all sites, including the Yahoo site featured in the tcpdump
below, just fine.  Also, if I configure the internal browsers to use a
squid proxy that lives outside the firewall, everything works.

I tried to include all my configuration info, below.  This server also
runs LVS to do some load balancing so the LVS config is also included.

Please remember I inherited this network, I did not build it.  I know
there are many things that can/should be done differently and they are
on my to-do list but I have to put out this fire first.

Any help is appreciated :-)

--Dave



#################################################
#
# tcpdump output of a "hung" HTTP connection
#
#################################################

1  08:24:03.424534 eth1 < 10.10.21.70.2388 > maps.vip.dcx.yahoo.com.http: S 3753411904:3753411904(0) win 
   5840 <mss 1460,sackOK,timestamp 38294599 0,nop,wscale 0> (DF)
2  08:24:03.424610 eth0 > xxx.yyy.zzz.80.2388 > maps.vip.dcx.yahoo.com.http: S 3753411904:3753411904(0) win 
   5840 <mss 1460,sackOK,timestamp 38294599 0,nop,wscale 0> (DF)
3  08:24:03.477198 eth0 < maps.vip.dcx.yahoo.com.http > xxx.yyy.zzz.80.2388: S 2180038608:2180038608(0) 
   ack 3753411905 win 17520 <mss 1460> (DF)
4  08:24:03.477237 eth1 > maps.vip.dcx.yahoo.com.http > 10.10.21.70.2388: S 2180038608:2180038608(0) 
   ack 3753411905 win 17520 <mss 1460> (DF)
5  08:24:03.477356 eth1 < 10.10.21.70.2388 > maps.vip.dcx.yahoo.com.http: . 1:1(0) ack 1 win 5840 (DF)
6  08:24:03.477388 eth0 > xxx.yyy.zzz.80.2388 > maps.vip.dcx.yahoo.com.http: . 1:1(0) ack 1 win 5840 (DF)
7  08:24:03.477600 eth1 < 10.10.21.70.2388 > maps.vip.dcx.yahoo.com.http: P 1:199(198) ack 1 win 5840 (DF)
8  08:24:03.477638 eth0 > xxx.yyy.zzz.80.2388 > maps.vip.dcx.yahoo.com.http: P 1:199(198) ack 1 win 5840 (DF)
9  08:24:03.533992 eth0 < maps.vip.dcx.yahoo.com.http > xxx.yyy.zzz.80.2388: . 1:1461(1460) ack 199 win 17520 (DF)
10 08:24:03.534025 eth1 > maps.vip.dcx.yahoo.com.http > 10.10.21.70.2388: . 1:1461(1460) ack 199 win 17520 (DF)
11 08:24:03.534248 eth0 < maps.vip.dcx.yahoo.com.http > xxx.yyy.zzz.80.2388: . 1461:2921(1460) ack 199 win 17520 (DF)
12 08:24:03.534284 eth1 > maps.vip.dcx.yahoo.com.http > 10.10.21.70.2388: . 1461:2921(1460) ack 199 win 17520 (DF)
13 08:24:03.534412 eth1 < 10.10.21.70.2388 > maps.vip.dcx.yahoo.com.http: . 199:199(0) ack 1461 win 8760 (DF)
14 08:24:03.534440 eth0 > xxx.yyy.zzz.80.2388 > maps.vip.dcx.yahoo.com.http: . 199:199(0) ack 1461 win 8760 (DF)
15 08:24:03.534757 eth0 < maps.vip.dcx.yahoo.com.http > xxx.yyy.zzz.80.2388: . 2921:4381(1460) ack 199 win 17520 (DF)
16 08:24:03.534792 eth1 > maps.vip.dcx.yahoo.com.http > 10.10.21.70.2388: . 2921:4381(1460) ack 199 win 17520 (DF)
17 08:24:03.534913 eth1 < 10.10.21.70.2388 > maps.vip.dcx.yahoo.com.http: . 199:199(0) ack 2921 win 11680 (DF)
18 08:24:03.534942 eth0 > xxx.yyy.zzz.80.2388 > maps.vip.dcx.yahoo.com.http: . 199:199(0) ack 2921 win 11680 (DF)
19 08:24:03.535411 eth1 < 10.10.21.70.2388 > maps.vip.dcx.yahoo.com.http: . 199:199(0) ack 4381 win 14600 (DF)
20 08:24:03.535443 eth0 > xxx.yyy.zzz.80.2388 > maps.vip.dcx.yahoo.com.http: . 199:199(0) ack 4381 win 14600 (DF)
21 08:24:04.526493 eth0 < maps.vip.dcx.yahoo.com.http > xxx.yyy.zzz.80.2388: . 1:1461(1460) ack 199 win 17520 (DF)
22 08:24:04.526525 eth1 > maps.vip.dcx.yahoo.com.http > 10.10.21.70.2388: . 1:1461(1460) ack 199 win 17520 (DF)
23 08:24:04.526906 eth1 < 10.10.21.70.2388 > maps.vip.dcx.yahoo.com.http: . 199:199(0) ack 4381 win 14600 (DF)
24 08:24:04.526942 eth0 > xxx.yyy.zzz.80.2388 > maps.vip.dcx.yahoo.com.http: . 199:199(0) ack 4381 win 14600 (DF)
25 08:24:06.526806 eth0 < maps.vip.dcx.yahoo.com.http > xxx.yyy.zzz.80.2388: . 1:1461(1460) ack 199 win 17520 (DF)
26 08:24:06.526850 eth1 > maps.vip.dcx.yahoo.com.http > 10.10.21.70.2388: . 1:1461(1460) ack 199 win 17520 (DF)
27 08:24:06.527239 eth1 < 10.10.21.70.2388 > maps.vip.dcx.yahoo.com.http: . 199:199(0) ack 4381 win 14600 (DF)
28 08:24:06.527277 eth0 > xxx.yyy.zzz.80.2388 > maps.vip.dcx.yahoo.com.http: . 199:199(0) ack 4381 win 14600 (DF)
29 08:24:06.743982 eth1 < 10.10.21.70.2388 > maps.vip.dcx.yahoo.com.http: F 199:199(0) ack 4381 win 14600 (DF)
30 08:24:06.744011 eth0 > xxx.yyy.zzz.80.2388 > maps.vip.dcx.yahoo.com.http: F 199:199(0) ack 4381 win 14600 (DF)
31 08:24:07.039906 eth1 < 10.10.21.70.2388 > maps.vip.dcx.yahoo.com.http: F 199:199(0) ack 4381 win 14600 (DF)
32 08:24:07.039941 eth0 > xxx.yyy.zzz.80.2388 > maps.vip.dcx.yahoo.com.http: F 199:199(0) ack 4381 win 14600 (DF)
33 08:24:07.639900 eth1 < 10.10.21.70.2388 > maps.vip.dcx.yahoo.com.http: F 199:199(0) ack 4381 win 14600 (DF)
34 08:24:07.639949 eth0 > xxx.yyy.zzz.80.2388 > maps.vip.dcx.yahoo.com.http: F 199:199(0) ack 4381 win 14600 (DF)
35 08:24:08.839884 eth1 < 10.10.21.70.2388 > maps.vip.dcx.yahoo.com.http: F 199:199(0) ack 4381 win 14600 (DF)
36 08:24:08.839922 eth0 > xxx.yyy.zzz.80.2388 > maps.vip.dcx.yahoo.com.http: F 199:199(0) ack 4381 win 14600 (DF)





##########################################
#
# Current iptables rules:
#
##########################################

[root@fw1 ipt-conf]# iptables -t filter -L --line -nv; iptables -t nat -L --line -nv;iptables -t mangle -L --line -nv
Chain INPUT (policy DROP 3 packets, 132 bytes)
num   pkts bytes target     prot opt in     out     source               destination         
1     3855  298K ACCEPT     all  --  lo     *       0.0.0.0/0            0.0.0.0/0          
2        0     0 LOG        all  -f  eth0   *       0.0.0.0/0            0.0.0.0/0          LOG flags 0 level 4 prefix `IPT:FRAG ' 
3        0     0 DROP       all  -f  eth0   *       0.0.0.0/0            0.0.0.0/0          
4      339  251K ACCEPT     all  --  eth2   *       0.0.0.0/0            0.0.0.0/0          
5      <sensitive rule removed>
6        0     0 ACCEPT     all  --  eth1   *       10.200.200.252       0.0.0.0/0          
7      512 38908 ACCEPT     all  --  eth1   *       10.200.200.253       0.0.0.0/0          
8        0     0 ACCEPT     all  --  eth1   *       10.200.200.254       0.0.0.0/0          
9       31  2604 ACCEPT     all  --  eth0   *       xxx.yyy.zzz.64/27    0.0.0.0/0          
10     174 39235 ACCEPT     all  --  eth0   *       0.0.0.0/0            xxx.yyy.zzz.80       
11      12   612 ACCEPT     tcp  --  eth1   *       10.200.200.0/24      0.0.0.0/0          tcp dpt:22 
12      86  5248 ACCEPT     tcp  --  eth1   *       10.10.21.0/24        0.0.0.0/0          tcp dpt:22 
13     106  6711 ACCEPT     all  --  eth1   *       10.10.21.70          0.0.0.0/0          
14       0     0 ACCEPT     icmp --  eth1   *       10.200.200.0/24      0.0.0.0/0          
15       2   120 ACCEPT     icmp --  eth1   *       10.10.21.0/24        0.0.0.0/0          
16       0     0 ACCEPT     udp  --  eth1   *       10.200.200.0/24      0.0.0.0/0          udp dpt:694 
17       4   480 ACCEPT     udp  --  eth1   *       10.200.200.4         0.0.0.0/0          udp dpt:161 
18       0     0 ACCEPT     tcp  --  eth1   *       10.200.200.4         0.0.0.0/0          tcp dpt:617 
19     178 10948 ACCEPT     tcp  --  eth1   *       10.200.200.0/24      0.0.0.0/0          
20       0     0 ACCEPT     tcp  --  eth0   *       mmm.nnn.ooo.ppp      0.0.0.0/0          tcp spt:53 state ESTABLISHED 
21       0     0 ACCEPT     udp  --  eth0   *       mmm.nnn.ooo.ppp      0.0.0.0/0          udp spt:53 state ESTABLISHED 
22       0     0 ACCEPT     tcp  --  eth0   *       mmm.nnn.ooo.ppp      0.0.0.0/0          tcp spt:53 state ESTABLISHED 
23       0     0 ACCEPT     udp  --  eth0   *       mmm.nnn.ooo.ppp      0.0.0.0/0          udp spt:53 state ESTABLISHED 
24       0     0 ACCEPT     tcp  --  eth1   *       10.10.21.70          0.0.0.0/0          tcp spt:53 state ESTABLISHED 
25       0     0 ACCEPT     udp  --  eth1   *       10.10.21.70          0.0.0.0/0          udp spt:53 state ESTABLISHED 
26       0     0 ACCEPT     tcp  --  eth1   *       10.200.200.4         0.0.0.0/0          tcp spt:53 state ESTABLISHED 
27       0     0 ACCEPT     udp  --  eth1   *       10.200.200.4         0.0.0.0/0          udp spt:53 state ESTABLISHED 
28       0     0 ACCEPT     tcp  --  eth0   *       0.0.0.0/0            0.0.0.0/0          tcp spt:25 state ESTABLISHED 
29       0     0 ACCEPT     tcp  --  eth1   *       0.0.0.0/0            0.0.0.0/0          tcp spt:25 state ESTABLISHED 
30      15   969 ACCEPT     tcp  --  eth0   *       0.0.0.0/0            xxx.yyy.zzz.66     tcp dpt:80 
31      35  3991 ACCEPT     tcp  --  eth0   *       0.0.0.0/0            xxx.yyy.zzz.66     tcp dpt:443 
32       5   200 ACCEPT     tcp  --  eth0   *       0.0.0.0/0            xxx.yyy.zzz.67     tcp dpt:80 
33     128 19010 ACCEPT     tcp  --  eth0   *       0.0.0.0/0            xxx.yyy.zzz.67     tcp dpt:443 
34       0     0 ACCEPT     tcp  --  eth1   *       10.10.21.0/24        xxx.yyy.zzz.66     tcp dpt:80 
35       0     0 ACCEPT     tcp  --  eth1   *       10.200.200.0/24      xxx.yyy.zzz.66     tcp dpt:80 
36       0     0 ACCEPT     tcp  --  eth1   *       10.10.21.0/24        xxx.yyy.zzz.66     tcp dpt:443 
37       0     0 ACCEPT     tcp  --  eth1   *       10.200.200.0/24      xxx.yyy.zzz.66     tcp dpt:443 
38       0     0 ACCEPT     tcp  --  eth1   *       10.10.21.0/24        xxx.yyy.zzz.67     tcp dpt:80 
39       0     0 ACCEPT     tcp  --  eth1   *       10.200.200.0/24      xxx.yyy.zzz.67     tcp dpt:80 
40       0     0 ACCEPT     tcp  --  eth1   *       10.10.21.0/24        xxx.yyy.zzz.67     tcp dpt:443 
41       0     0 ACCEPT     tcp  --  eth1   *       10.200.200.0/24      xxx.yyy.zzz.67     tcp dpt:443 
42    1843  274K ACCEPT     tcp  --  eth1   *       10.10.21.0/24        10.200.200.169     tcp dpt:80 
43       0     0 ACCEPT     tcp  --  eth1   *       10.200.200.0/24      10.200.200.169     tcp dpt:80 
44       3   234 DROP       udp  --  eth1   *       0.0.0.0/0            0.0.0.0/0          udp dpt:137 
45       0     0 DROP       udp  --  eth1   *       0.0.0.0/0            0.0.0.0/0          udp dpt:138 
46       3   144 LOG        all  --  *      *       0.0.0.0/0            0.0.0.0/0          LOG flags 0 level 4 prefix `IPT:INPUT ' 
47       3   144 DROP       all  --  *      *       0.0.0.0/0            0.0.0.0/0          

Chain FORWARD (policy DROP 0 packets, 0 bytes)
num   pkts bytes target     prot opt in     out     source               destination         
1       57 47996 ACCEPT     tcp  --  eth0   *       0.0.0.0/0            10.10.21.23        tcp dpt:25 state NEW,ESTABLISHED 
2       39  2454 ACCEPT     tcp  --  eth1   *       10.10.21.23          0.0.0.0/0          tcp spt:25 state ESTABLISHED 
3        0     0 ACCEPT     udp  --  eth0   *       0.0.0.0/0            10.10.21.23        udp dpt:25 state NEW,ESTABLISHED 
4        0     0 ACCEPT     udp  --  eth1   *       10.10.21.23          0.0.0.0/0          udp spt:25 state ESTABLISHED 
5        0     0 ACCEPT     tcp  --  eth0   *       0.0.0.0/0            10.10.21.23        tcp dpt:110 state NEW,ESTABLISHED 
6        0     0 ACCEPT     tcp  --  eth1   *       10.10.21.23          0.0.0.0/0          tcp spt:110 state ESTABLISHED 
7        0     0 ACCEPT     udp  --  eth0   *       0.0.0.0/0            10.10.21.23        udp dpt:110 state NEW,ESTABLISHED 
8        0     0 ACCEPT     udp  --  eth1   *       10.10.21.23          0.0.0.0/0          udp spt:110 state ESTABLISHED 
9        0     0 ACCEPT     tcp  --  eth0   *       0.0.0.0/0            10.10.21.24        tcp dpt:22 state NEW,ESTABLISHED 
10       0     0 ACCEPT     tcp  --  eth1   *       10.10.21.24          0.0.0.0/0          tcp spt:22 state ESTABLISHED 
11       0     0 ACCEPT     tcp  --  eth0   *       0.0.0.0/0            10.200.200.4       tcp dpt:22 state NEW,ESTABLISHED 
12       0     0 ACCEPT     tcp  --  eth1   *       10.200.200.4         0.0.0.0/0          tcp spt:22 state ESTABLISHED 
13     322 69268 ACCEPT     all  --  eth1   eth0    10.200.200.0/24      0.0.0.0/0          state NEW,RELATED,ESTABLISHED 
14      60  8142 ACCEPT     all  --  eth0   eth1    0.0.0.0/0            10.200.200.0/24    state RELATED,ESTABLISHED 
15    1362  158K ACCEPT     all  --  eth1   eth0    10.10.21.0/24        0.0.0.0/0          state NEW,RELATED,ESTABLISHED 
16    1369  665K ACCEPT     all  --  eth0   eth1    0.0.0.0/0            10.10.21.0/24      state RELATED,ESTABLISHED 
17       0     0 ACCEPT     all  --  eth1   eth1    10.10.21.0/24        10.200.200.0/24    state NEW,RELATED,ESTABLISHED 
18    3212 1813K ACCEPT     all  --  eth1   eth1    10.200.200.0/24      10.10.21.0/24      state NEW,RELATED,ESTABLISHED 
19       0     0 ACCEPT     icmp --  eth1   eth1    10.200.200.0/24      10.10.21.0/24      icmp type 3 
20       0     0 ACCEPT     icmp --  *      *       0.0.0.0/0            10.10.21.70        
21       0     0 ACCEPT     icmp --  *      *       10.10.21.70          0.0.0.0/0          
22       0     0 LOG        all  --  *      *       0.0.0.0/0            0.0.0.0/0          LOG flags 0 level 4 prefix `IPT:FORWARD ' 
23       0     0 DROP       all  --  *      *       0.0.0.0/0            0.0.0.0/0          

Chain OUTPUT (policy DROP 0 packets, 0 bytes)
num   pkts bytes target     prot opt in     out     source               destination         
1     3855  298K ACCEPT     all  --  *      lo      0.0.0.0/0            0.0.0.0/0          
2      338  250K ACCEPT     all  --  *      eth2    0.0.0.0/0            0.0.0.0/0          
3     <sensitive rule removed>
4        0     0 ACCEPT     all  --  *      eth1    0.0.0.0/0            10.200.200.252     
5      511 38840 ACCEPT     all  --  *      eth1    0.0.0.0/0            10.200.200.253     
6        0     0 ACCEPT     all  --  *      eth1    0.0.0.0/0            10.200.200.254     
7       31  2604 ACCEPT     all  --  *      eth0    0.0.0.0/0            xxx.yyy.zzz.64/27    
8      156  6240 ACCEPT     all  --  *      eth0    xxx.yyy.zzz.80       0.0.0.0/0          
9       94 24435 ACCEPT     tcp  --  *      eth1    0.0.0.0/0            0.0.0.0/0          tcp spt:22 
10       0     0 ACCEPT     tcp  --  *      eth1    0.0.0.0/0            0.0.0.0/0          tcp spt:22 
11       0     0 ACCEPT     all  --  *      eth1    0.0.0.0/0            10.10.21.70        
12      17  1938 ACCEPT     icmp --  *      eth1    0.0.0.0/0            10.200.200.0/24    
13       2   120 ACCEPT     icmp --  *      eth1    0.0.0.0/0            10.10.21.0/24      
14       0     0 ACCEPT     udp  --  *      eth1    0.0.0.0/0            10.200.200.0/24    udp dpt:694 
15       4   600 ACCEPT     udp  --  *      eth1    0.0.0.0/0            10.200.200.4       udp spt:161 
16       0     0 ACCEPT     tcp  --  *      eth1    0.0.0.0/0            10.200.200.4       tcp spt:617 
17     157 11690 ACCEPT     tcp  --  *      eth1    0.0.0.0/0            10.200.200.0/24    
18       0     0 ACCEPT     tcp  --  *      eth0    0.0.0.0/0            mmm.nnn.ooo.ppp    tcp dpt:53 state NEW,ESTABLISHED 
19       0     0 ACCEPT     udp  --  *      eth0    0.0.0.0/0            mmm.nnn.ooo.ppp    udp dpt:53 state NEW,ESTABLISHED 
20       0     0 ACCEPT     tcp  --  *      eth0    0.0.0.0/0            mmm.nnn.ooo.ppp    tcp dpt:53 state NEW,ESTABLISHED 
21       0     0 ACCEPT     udp  --  *      eth0    0.0.0.0/0            mmm.nnn.ooo.ppp    udp dpt:53 state NEW,ESTABLISHED 
22       0     0 ACCEPT     tcp  --  *      eth1    0.0.0.0/0            10.10.21.70        tcp dpt:53 state NEW,ESTABLISHED 
23       0     0 ACCEPT     udp  --  *      eth1    0.0.0.0/0            10.10.21.70        udp dpt:53 state NEW,ESTABLISHED 
24       0     0 ACCEPT     tcp  --  *      eth1    0.0.0.0/0            10.200.200.4       tcp dpt:53 state NEW,ESTABLISHED 
25       0     0 ACCEPT     udp  --  *      eth1    0.0.0.0/0            10.200.200.4       udp dpt:53 state NEW,ESTABLISHED 
26       0     0 ACCEPT     tcp  --  *      eth0    0.0.0.0/0            0.0.0.0/0          tcp dpt:25 state NEW,ESTABLISHED 
27       0     0 ACCEPT     tcp  --  *      eth1    0.0.0.0/0            0.0.0.0/0          tcp dpt:25 state NEW,ESTABLISHED 
28       0     0 ACCEPT     tcp  --  *      eth0    xxx.yyy.zzz.66       0.0.0.0/0          tcp spt:80 
29       1    40 ACCEPT     tcp  --  *      eth0    xxx.yyy.zzz.66       0.0.0.0/0          tcp spt:443 
30       0     0 ACCEPT     tcp  --  *      eth0    xxx.yyy.zzz.67       0.0.0.0/0          tcp spt:80 
31       0     0 ACCEPT     tcp  --  *      eth0    xxx.yyy.zzz.67       0.0.0.0/0          tcp spt:443 
32       0     0 ACCEPT     tcp  --  *      eth1    xxx.yyy.zzz.66       10.10.21.0/24      tcp spt:80 
33       0     0 ACCEPT     tcp  --  *      eth1    xxx.yyy.zzz.66       10.200.200.0/24    tcp spt:80 
34       0     0 ACCEPT     tcp  --  *      eth1    xxx.yyy.zzz.66       10.10.21.0/24      tcp spt:443 
35       0     0 ACCEPT     tcp  --  *      eth1    xxx.yyy.zzz.66       10.200.200.0/24    tcp spt:443 
36       0     0 ACCEPT     tcp  --  *      eth1    xxx.yyy.zzz.67       10.10.21.0/24      tcp spt:80 
37       0     0 ACCEPT     tcp  --  *      eth1    xxx.yyy.zzz.67       10.200.200.0/24    tcp spt:80 
38       0     0 ACCEPT     tcp  --  *      eth1    xxx.yyy.zzz.67       10.10.21.0/24      tcp spt:443 
39       0     0 ACCEPT     tcp  --  *      eth1    xxx.yyy.zzz.67       10.200.200.0/24    tcp spt:443 
40       0     0 ACCEPT     tcp  --  *      eth1    10.200.200.169       10.10.21.0/24      tcp spt:80 
41       0     0 ACCEPT     tcp  --  *      eth1    10.200.200.169       10.200.200.0/24    tcp spt:80 
42       0     0 LOG        all  --  *      *       0.0.0.0/0            0.0.0.0/0          LOG flags 0 level 4 prefix `IPT:OUTPUT ' 
43       0     0 DROP       all  --  *      *       0.0.0.0/0            0.0.0.0/0          
Chain PREROUTING (policy ACCEPT 5884 packets, 2230408 bytes)
num   pkts bytes target     prot opt in     out     source               destination         
1        4  1260 DNAT       tcp  --  eth0   *       0.0.0.0/0            xxx.yyy.zzz.69       tcp dpt:25 to:10.10.21.23:25 
2        0     0 DNAT       udp  --  eth0   *       0.0.0.0/0            xxx.yyy.zzz.69       udp dpt:25 to:10.10.21.23:25 
3        0     0 DNAT       tcp  --  eth0   *       0.0.0.0/0            xxx.yyy.zzz.69       tcp dpt:110 to:10.10.21.23:110 
4        0     0 DNAT       udp  --  eth0   *       0.0.0.0/0            xxx.yyy.zzz.69       udp dpt:110 to:10.10.21.23:110 
5        0     0 DNAT       tcp  --  eth0   *       0.0.0.0/0            xxx.yyy.zzz.86       tcp dpt:22 to:10.10.21.24:22 
6        0     0 DNAT       tcp  --  eth0   *       0.0.0.0/0            xxx.yyy.zzz.84       tcp dpt:22 to:10.200.200.4:22 

Chain POSTROUTING (policy ACCEPT 47 packets, 7198 bytes)
num   pkts bytes target     prot opt in     out     source               destination         
1      100  4918 SNAT       all  --  *      eth0    10.10.21.0/24        0.0.0.0/0          to:xxx.yyy.zzz.80 
2       21  1597 SNAT       all  --  *      eth0    10.200.200.0/24      0.0.0.0/0          to:xxx.yyy.zzz.80 

Chain OUTPUT (policy ACCEPT 0 packets, 0 bytes)
num   pkts bytes target     prot opt in     out     source               destination         
Chain PREROUTING (policy ACCEPT 917 packets, 225511 bytes)
num   pkts bytes target     prot opt in     out     source               destination         

Chain OUTPUT (policy ACCEPT 465 packets, 67489 bytes)
num   pkts bytes target     prot opt in     out     source               destination


################################
#
# Linux Virtual Server Config 
#
################################

LVS Configuration
[root@fw1 ipt-conf]#  ipvsadm -l -n
IP Virtual Server version 0.2.7 (size=65536)                   
Prot LocalAddress:Port Scheduler Flags                         
  -> RemoteAddress:Port          Forward Weight ActiveConn InActConn
TCP  xxx.yyy.zzz.66:80 rr
  -> 10.200.200.12:80            Masq    1      0          6         
TCP  xxx.yyy.zzz.67:80 rr
  -> 10.200.200.22:80            Masq    1      0          1         
TCP  xxx.yyy.zzz.66:1080 rr
  -> 10.200.200.12:1080          Masq    1      0          0         
TCP  xxx.yyy.zzz.66:1443 rr
  -> 10.200.200.12:1443          Masq    1      0          0         
TCP  xxx.yyy.zzz.66:443 rr
  -> 10.200.200.12:443           Masq    1      0          0         
TCP  10.200.200.169:80 rr
  -> 10.200.200.32:80            Masq    1      1          21        
TCP  xxx.yyy.zzz.67:443 rr
  -> 10.200.200.22:443           Masq    1      0          0    


##################################
#
# Network Interfaces
#
##################################

ifconfig -a
[root@fw1 ipt-conf]# ifconfig -a
eth0      Link encap:Ethernet  HWaddr 00:50:8B:8F:BB:DB  
          inet addr:xxx.yyy.zzz.92  Bcast:xxx.yyy.zzz.95  Mask:255.255.255.224
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:535762 errors:12 dropped:0 overruns:0 frame:12
          TX packets:499986 errors:6 dropped:0 overruns:0 carrier:6
          collisions:10257 txqueuelen:100 
          Interrupt:15 Base address:0x2c80 

eth0:0    Link encap:Ethernet  HWaddr 00:50:8B:8F:BB:DB  
          inet addr:xxx.yyy.zzz.67  Bcast:xxx.yyy.zzz.95  Mask:255.255.255.224
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          Interrupt:15 Base address:0x2c80 

eth0:1    Link encap:Ethernet  HWaddr 00:50:8B:8F:BB:DB  
          inet addr:xxx.yyy.zzz.80  Bcast:xxx.yyy.zzz.95  Mask:255.255.255.224
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          Interrupt:15 Base address:0x2c80 

eth0:2    Link encap:Ethernet  HWaddr 00:50:8B:8F:BB:DB  
          inet addr:xxx.yyy.zzz.81  Bcast:xxx.yyy.zzz.95  Mask:255.255.255.224
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          Interrupt:15 Base address:0x2c80 

eth0:3    Link encap:Ethernet  HWaddr 00:50:8B:8F:BB:DB  
          inet addr:xxx.yyy.zzz.66  Bcast:xxx.yyy.zzz.95  Mask:255.255.255.224
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          Interrupt:15 Base address:0x2c80 

eth0:4    Link encap:Ethernet  HWaddr 00:50:8B:8F:BB:DB  
          inet addr:xxx.yyy.zzz.84  Bcast:xxx.yyy.zzz.95  Mask:255.255.255.224
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          Interrupt:15 Base address:0x2c80 

eth0:5    Link encap:Ethernet  HWaddr 00:50:8B:8F:BB:DB  
          inet addr:xxx.yyy.zzz.94  Bcast:xxx.yyy.zzz.95  Mask:255.255.255.224
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          Interrupt:15 Base address:0x2c80 

eth0:6    Link encap:Ethernet  HWaddr 00:50:8B:8F:BB:DB  
          inet addr:xxx.yyy.zzz.69  Bcast:xxx.yyy.zzz.95  Mask:255.255.255.224
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          Interrupt:15 Base address:0x2c80 

eth1      Link encap:Ethernet  HWaddr 00:08:C7:CF:8D:0B  
          inet addr:10.200.200.252  Bcast:10.200.200.255  Mask:255.255.255.0
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:1883587 errors:72 dropped:0 overruns:0 frame:72
          TX packets:1883269 errors:31 dropped:0 overruns:0 carrier:31
          collisions:23552 txqueuelen:100 
          Interrupt:5 Base address:0x2c90 

eth1:0    Link encap:Ethernet  HWaddr 00:08:C7:CF:8D:0B  
          inet addr:10.200.200.169  Bcast:10.200.200.255  Mask:255.255.255.0
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          Interrupt:5 Base address:0x2c90 

eth1:1    Link encap:Ethernet  HWaddr 00:08:C7:CF:8D:0B  
          inet addr:10.200.200.254  Bcast:10.200.200.255  Mask:255.255.255.0
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          Interrupt:5 Base address:0x2c90 

eth2      Link encap:Ethernet  HWaddr 00:04:76:B9:AD:96  
          inet addr:192.168.0.1  Bcast:192.168.0.255  Mask:255.255.255.0
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:279133 errors:0 dropped:0 overruns:0 frame:0
          TX packets:277027 errors:0 dropped:0 overruns:0 carrier:252
          collisions:0 txqueuelen:100 
          Interrupt:15 Base address:0x2c00 

lo        Link encap:Local Loopback  
          inet addr:127.0.0.1  Mask:255.0.0.0
          UP LOOPBACK RUNNING  MTU:16436  Metric:1
          RX packets:3131240 errors:0 dropped:0 overruns:0 frame:0
          TX packets:3131240 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 

###################################
#
# Other OS info
#
###################################

[root@fw1 ipt-conf]#  uname -a
Linux fw1.abcxyz.com 2.4.3-12 #1 Fri Jun 8 13:35:30 EDT 2001 i686 unknown
[root@fw1 ipt-conf]# iptables --version
iptables v1.2.1a
[root@fw1 ipt-conf]# cat /etc/redhat-release 
Red Hat Linux release 7.1 (Seawolf)

[root@fw1 ipt-conf]# lsmod
Module                  Size  Used by
iptable_mangle          1696   0  (autoclean) (unused)
iptable_nat            11888   0  (autoclean) (unused)
ip_vs_rr                 816   7  (autoclean)
ip_vs                  49408  31  [ip_vs_rr]
softdog                 1472   0  (unused)
3c59x                  23264   1  (autoclean)
tlan                   23472   2  (autoclean)
ipt_state                544  38  (autoclean)
ipt_LOG                 3216   4  (autoclean)
ip_conntrack           11824   2  (autoclean) [iptable_nat ipt_state]
iptable_filter          1696   0  (autoclean) (unused)
ip_tables              10272   7  [iptable_mangle iptable_nat ipt_state ipt_LOG iptable_filter]
sym53c8xx              53248   0  (unused)
cpqarray               16208   7 
sd_mod                 11104   0  (unused)
scsi_mod               84416   2  [sym53c8xx sd_mod]

[root@fw1 ipv4]# cat ip_conntrack_max 
16384

-- 
Dave Herrald
dave@fropa.com