Re: IP Tables - Can't access devices when IP Tables are active
Posted: 2017/02/07 12:14:31
No, OUPUT is set to accept, so everything should flow through there.
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I did not realize that you run the 'snmpwalk' in the server, reaching out.How do I listen to the interface and do an snmp check from the server at the same time?
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# start tcpdump as asynchronous background process
# and direct output to a file
tcpdump -n -nn -l -i any not port 22 > fw-snmp-test.log &
# run the test
snmpwalk -v 2c -c public 10.0.0.51
# bring the tcpdump back to foreground
fg
# quit tcpdump with Ctrl-c
# look at the traffic
less fw-snmp-test.log
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[root@SERVERDNS ~]# tcpdump -n -nn -l -i any not port 22 > fw-snmp-test.log &
[2] 1297
[root@SERVERDNS ~]# tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on any, link-type LINUX_SLL (Linux cooked), capture size 65535 bytes
tcpdump -n -nn -l -i asnmpwalk -v 2c -c public 10.0.0.51
Timeout: No Response from 10.0.0.51
[root@SERVERDNS ~]# fg
tcpdump -n -nn -l -i any not port 22 > fw-snmp-test.log
^C7393 packets captured
13610 packets received by filter
149 packets dropped by kernel
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less fw-snmp-test.log
09:40:12.866477 ARP, Request who-has SOME PUBLIC IP A tell SOME PUBLIC IP B, length 46
09:40:12.876934 ARP, Request who-has SOME PUBLIC IP C tell SOME PUBLIC IP B, length 46
09:40:12.898834 IP 10.13.0.98.137 > 10.13.0.255.137: NBT UDP PACKET(137): QUERY; REQUEST; BROADCAST
09:40:12.899260 IP 10.13.0.98.55864 > 224.0.0.252.5355: UDP, length 24
09:40:12.899601 IP 192.168.0.198.137 > 192.168.0.255.137: NBT UDP PACKET(137): QUERY; REQUEST; BROADCAST
09:40:12.899966 IP 192.168.0.198.50394 > 224.0.0.252.5355: UDP, length 24
09:40:12.900799 IP 10.13.0.98.137 > 10.13.0.255.137: NBT UDP PACKET(137): QUERY; REQUEST; BROADCAST
09:40:12.901086 IP 10.13.0.98.53798 > 224.0.0.252.5355: UDP, length 24
09:40:12.901333 IP 192.168.0.198.137 > 192.168.0.255.137: NBT UDP PACKET(137): QUERY; REQUEST; BROADCAST
09:40:12.901659 IP 192.168.0.198.60249 > 224.0.0.252.5355: UDP, length 24
09:40:12.914256 ARP, Request who-has SOME PUBLIC IP D tell SOME PUBLIC IP B, length 46
09:40:12.918157 ARP, Request who-has SOME PUBLIC IP E tell SOME PUBLIC IP B, length 46
09:40:12.959472 IP 127.0.0.1.48991 > 127.0.0.1.5432: Flags [P.], seq 2050600983:2050601040, ack 4111920964, win 1585, options [nop,nop,TS val 523888952 ecr 523887950], length 57