I have several CentOS instances on Amazon's AWS/EC2.
The instances are able to ping each other, but not SNMP or traceroute among themselves.
More data:
I stopped iptables on all machines
each instance is able to traceroute and talk SNMP to itself.
Addresses of two of the machines: 10.152.143.130 10.211.155.240

Can you suggest where the problem may lie?

Not necessary unless you (want to) know zilch about iptables or expose all services unrestricted on those machines. And "debugging" an iptables rule set isn't difficult: just use "-j LOG" rules before making REJECT / DROP / TARPIT / whatever else decisions.


Show us 'route -n', actual (tcp)traceroute and verbose snmpwalk data from both machines?

*Or else try via these machines public IP addresses? Note if you use SNMP your should use v3, restrict access to only your machines, set a non-std community name and use its authentication features.

Thanks unSpawn for your answer.
Per the above, I turned firewalling back on.
Below (note that I had to trim the `snmpwalk -DALL` output, to get under the 30000 characters limit of linuxquestions.org)
The environment is for debugging a certain problem we ancounter, it will never go to production, and the simulation is for SNMP 1 and 2c.

First Machine:
[root@domU-12-31-39-0A-98-02 snmp]# service iptables status
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 state NEW tcp dpt:11211
6 ACCEPT udp -- 0.0.0.0/0 0.0.0.0/0 state NEW udp dpt:11211
7 ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 state NEW,ESTABLISHED tcp dpt:8080
8 ACCEPT udp -- 0.0.0.0/0 0.0.0.0/0 state NEW udp dpt:514
9 ACCEPT udp -- 0.0.0.0/0 0.0.0.0/0 state NEW udp dpt:162
10 DROP all -- 0.0.0.0/0 0.0.0.0/0

Chain FORWARD (policy ACCEPT)
num target prot opt source destination
1 REJECT all -- 0.0.0.0/0 0.0.0.0/0 reject-with icmp-host-prohibited

Chain OUTPUT (policy ACCEPT)
num target prot opt source destination
1 ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 state NEW,ESTABLISHED tcp spts:1024:65535 dpt:8080

[root@domU-12-31-39-0A-98-02 snmp]# ping -c 3 ec2-54-234-96-235.compute-1.amazonaws.com
PING ec2-54-234-96-235.compute-1.amazonaws.com (10.152.143.130) 56(84) bytes of data.
64 bytes from ip-10-152-143-130.ec2.internal (10.152.143.130): icmp_seq=1 ttl=56 time=1.80 ms
64 bytes from ip-10-152-143-130.ec2.internal (10.152.143.130): icmp_seq=2 ttl=56 time=2.08 ms
64 bytes from ip-10-152-143-130.ec2.internal (10.152.143.130): icmp_seq=3 ttl=56 time=1.93 ms

--- ec2-54-234-96-235.compute-1.amazonaws.com ping statistics ---
3 packets transmitted, 3 received, 0% packet loss, time 2004ms
rtt min/avg/max/mdev = 1.802/1.937/2.080/0.124 ms
[root@domU-12-31-39-0A-98-02 snmp]# route -n
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
10.211.154.0 0.0.0.0 255.255.254.0 U 0 0 0 eth0
169.254.0.0 0.0.0.0 255.255.0.0 U 1002 0 0 eth0
0.0.0.0 10.211.154.1 0.0.0.0 UG 0 0 0 eth0
[root@domU-12-31-39-0A-98-02 snmp]# traceroute ec2-54-234-96-235.compute-1.amazonaws.com traceroute to ec2-54-234-96-235.compute-1.amazonaws.com (10.152.143.130), 30 hops max, 60 byte packets
1 * * *
...
30 * * *
[root@domU-12-31-39-0A-98-02 snmp]# snmpwalk -v 2c -c public -DALL ec2-54-234-96-235.compute-1.amazonaws.com .1.3.6.1.2.1.1.1
No log handling enabled - turning on stderr logging
trace: snmp_parse_args(): snmp_parse_args.c, 613:
snmp_parse_args: finished: 6/8
trace: netsnmp_ds_set_string(): default_store.c, 283:
netsnmp_ds_set_string: Setting LIB:6 = "snmpapp"
container_registry: registered container factory binary_array (binary_array)
container_registry: registered container factory sorted_singly_linked_list (sorted_singly_linked_list)
container_registry: registered container factory unsorted_singly_linked_list (unsorted_singly_linked_list-lifo)
container_registry: registered container factory lifo (unsorted_singly_linked_list-lifo)
container_registry: registered container factory fifo (unsorted_singly_linked_list-fifo)
trace: netsnmp_container_get_null_factory(): container_null.c, 173:
container:null:get_null_factory: in
container_registry: registered container factory null (null)
container_registry: registered container factory table_container (binary_array)
container_registry: registered container factory linked_list (sorted_singly_linked_list)
container_registry: registered container factory ssll_container (sorted_singly_linked_list)
container_registry: registered container factory cstring (binary_array)
container_registry: registered container factory string (binary_array)
container_registry: registered container factory string_binary_array (binary_array)
trace: init_callbacks(): callback.c, 192:
callback: initialized
trace: _callback_lock(): callback.c, 130:
9:callback:lock: locked (LIB,POST_READ_CONFIG)
trace: netsnmp_register_callback(): callback.c, 274:
callback: registered (0,0) at 0x2403ec0 with priority 0
trace: _callback_unlock(): callback.c, 164:
9:callback:lock: unlocked (LIB,POST_READ_CONFIG)
trace: _callback_lock(): callback.c, 130:
9:callback:lock: locked (LIB,POST_PREMIB_READ_CONFIG)
trace: netsnmp_register_callback(): callback.c, 274:
callback: registered (0,3) at 0x2403ef0 with priority 0
trace: _callback_unlock(): callback.c, 164:
9:callback:lock: unlocked (LIB,POST_PREMIB_READ_CONFIG)
trace: _callback_lock(): callback.c, 130:
9:callback:lock: locked (LIB,STORE_DATA)
trace: netsnmp_register_callback(): callback.c, 274:
callback: registered (0,1) at 0x2403f40 with priority 0
trace: _callback_unlock(): callback.c, 164:
9:callback:lock: unlocked (LIB,STORE_DATA)
trace: _callback_lock(): callback.c, 130:
9:callback:lock: locked (LIB,SHUTDOWN)
trace: netsnmp_register_callback(): callback.c, 274:
callback: registered (0,2) at 0x2403f70 with priority 0
trace: _callback_unlock(): callback.c, 164:
9:callback:lock: unlocked (LIB,SHUTDOWN)
trace: _callback_lock(): callback.c, 130:
9:callback:lock: locked (LIB,SESSION_INIT)
trace: netsnmp_register_callback(): callback.c, 274:
callback: registered (0,5) at 0x2403fa0 with priority 0
trace: _callback_unlock(): callback.c, 164:
9:callback:lock: unlocked (LIB,SESSION_INIT)
trace: init_usm(): snmpusm.c, 2726:
init_usm: unit_usm: 1 3
trace: _callback_lock(): callback.c, 130:
9:callback:lock: locked (LIB,POST_PREMIB_READ_CONFIG)
trace: netsnmp_register_callback(): callback.c, 274:
callback: registered (0,3) at 0x2404160 with priority 0
trace: _callback_unlock(): callback.c, 164:
9:callback:lock: unlocked (LIB,POST_PREMIB_READ_CONFIG)
trace: _callback_lock(): callback.c, 130:
9:callback:lock: locked (LIB,SHUTDOWN)
trace: netsnmp_register_callback(): callback.c, 274:
callback: registered (0,2) at 0x2404190 with priority 0
trace: _callback_unlock(): callback.c, 164:
9:callback:lock: unlocked (LIB,SHUTDOWN)
trace: _callback_lock(): callback.c, 130:
9:callback:lock: locked (LIB,SHUTDOWN)
trace: netsnmp_register_callback(): callback.c, 274:
callback: registered (0,2) at 0x24041c0 with priority 0
trace: _callback_unlock(): callback.c, 164:
9:callback:lock: unlocked (LIB,SHUTDOWN)
trace: _callback_lock(): callback.c, 130:
9:callback:lock: locked (LIB,POST_READ_CONFIG)
trace: netsnmp_register_callback(): callback.c, 274:
callback: registered (0,0) at 0x2405150 with priority 0
trace: _callback_unlock(): callback.c, 164:
9:callback:lock: unlocked (LIB,POST_READ_CONFIG)
trace: _callback_lock(): callback.c, 130:
9:callback:lock: locked (LIB,(null))
trace: snmp_call_callbacks(): callback.c, 322:
callback: START calling callbacks for maj=0 min=8
trace: snmp_call_callbacks(): callback.c, 348:
callback: END calling callbacks for maj=0 min=8 (0 called)
trace: _callback_unlock(): callback.c, 164:
9:callback:lock: unlocked (LIB,(null))
trace: read_premib_configs(): read_config.c, 874:
read_config: reading premib configuration tokens
trace: netsnmp_ds_set_string(): default_store.c, 283:
netsnmp_ds_set_string: Setting LIB:9 = "/etc/snmp:/usr/share/snmp:/usr/lib64/snmp:/root/.snmp"
trace: netsnmp_ds_set_string(): default_store.c, 283:
netsnmp_ds_set_string: Setting LIB:8 = "/var/lib/net-snmp"
trace: read_config_files_in_path(): read_config.c, 1038:
read_config: config path used for snmpwalk:/etc/snmp:/usr/share/snmp:/usr/lib64/snmp:/root/.snmp (persistent path:/var/lib/net-snmp)
trace: read_config_files_in_path(): read_config.c, 1049:
read_config: config dir: /etc/snmp
trace: read_config(): read_config.c, 707:
read_config: /etc/snmp/snmpwalk.conf: No such file or directory
...
trace: do_linkup(): parse.c, 1744:
parse-mibs: Processing import: TimeStamp
trace: do_linkup(): parse.c, 1744:
parse-mibs: Processing import: RowPointer
trace: do_linkup(): parse.c, 1744:
parse-mibs: Processing import: TestAndIncr
trace: do_linkup(): parse.c, 1744:
parse-mibs: Processing import: RowStatus
trace: do_linkup(): parse.c, 1744:
parse-mibs: Processing import: StorageType
trace: do_linkup(): parse.c, 1744:
parse-mibs: Processing import: InetAddress
trace: do_linkup(): parse.c, 1744:
parse-mibs: Processing import: InetAddressType
trace: do_linkup(): parse.c, 1744:
parse-mibs: Processing import: InetAddressPrefixLength
trace: do_linkup(): parse.c, 1744:
parse-mibs: Processing import: InetVersion
trace: do_linkup(): parse.c, 1744:
parse-mibs: Processing import: InetZoneIndex
trace: do_linkup(): parse.c, 1744:
parse-mibs: Processing import: InterfaceIndex
trace: parse(): parse.c, 4525:
parse-file: End of file (/usr/share/snmp/mibs/IP-MIB.txt)
trace: read_module_internal(): parse.c, 3871:
parse-mibs: Module IF-MIB already loaded
trace: read_module_internal(): parse.c, 3871:
parse-mibs: Module SNMPv2-MIB already loaded
trace: parse(): parse.c, 4273:
parse-file: Parsing file: /usr/share/snmp/mibs/RFC1213-MIB.txt...
...
trace: _callback_unlock(): callback.c, 164:
9:callback:lock: unlocked (LIB,POST_READ_CONFIG)
trace: netsnmp_tdomain_transport_full(): snmp_transport.c, 367:
tdomain: tdomain_transport_full("snmp", "ec2-54-234-96-235.compute-1.amazonaws.com", 0, "udp", "[NIL]")
trace: netsnmp_tdomain_transport_full(): snmp_transport.c, 399:
tdomain: Use user specified default domain "udp"
trace: find_tdomain(): snmp_transport.c, 340:
tdomain: Found domain "udp" from specifier "udp"
trace: netsnmp_lookup_default_target(): snmp_service.c, 388:
defaults: netsnmp_lookup_default_target("snmp", "udp") -> ":161"
trace: netsnmp_tdomain_transport_full(): snmp_transport.c, 439:
tdomain: trying domain "udp" address "ec2-54-234-96-235.compute-1.amazonaws.com" default address ":161"
trace: netsnmp_sockaddr_in2(): snmpUDPDomain.c, 842:
netsnmp_sockaddr_in: addr 0x7fffd1661eb0, inpeername "ec2-54-234-96-235.compute-1.amazonaws.com", default_target ":161"
trace: netsnmp_sockaddr_in2(): snmpUDPDomain.c, 842:
netsnmp_sockaddr_in: addr 0x7fffd1661eb0, inpeername ":161", default_target "[NIL]"
trace: netsnmp_sockaddr_in2(): snmpUDPDomain.c, 897:
netsnmp_sockaddr_in: check user service 161
trace: netsnmp_sockaddr_in2(): snmpUDPDomain.c, 956:
netsnmp_sockaddr_in: return { AF_INET, 0.0.0.0:161 }
trace: netsnmp_sockaddr_in2(): snmpUDPDomain.c, 897:
netsnmp_sockaddr_in: check user service ec2-54-234-96-235.compute-1.amazonaws.com
trace: netsnmp_sockaddr_in2(): snmpUDPDomain.c, 906:
netsnmp_sockaddr_in: servname not numeric, check if it really is a destination)
trace: netsnmp_sockaddr_in2(): snmpUDPDomain.c, 926:
netsnmp_sockaddr_in: check destination ec2-54-234-96-235.compute-1.amazonaws.com
trace: netsnmp_sockaddr_in2(): snmpUDPDomain.c, 945:
netsnmp_sockaddr_in: hostname (resolved okay)
trace: netsnmp_sockaddr_in2(): snmpUDPDomain.c, 956:
netsnmp_sockaddr_in: return { AF_INET, 10.152.143.130:161 }
trace: netsnmp_udp_transport(): snmpUDPDomain.c, 644:
netsnmp_udp: open remote UDP: [10.152.143.130]:161->[0.0.0.0]
daemonize: sysname 'Linux',
release '2.6.32-279.11.1.el6.x86_64',
version '#1 SMP Tue Oct 16 15:57:10 UTC 2012',
machine 'x86_64'
trace: _sock_buffer_size_get(): snmpUDPDomain.c, 482:
socket:buffer: Requested client send buffer is 0
verbose:socket:buffer: Original client send buffer is 229376
verbose:socket:buffer: New client send buffer size is smaller than original!
socket:buffer: client send buffer not valid or not specified; using OS default(229376)
trace: _sock_buffer_size_get(): snmpUDPDomain.c, 482:
socket:buffer: Requested client receive buffer is 0
verbose:socket:buffer: Original client receive buffer is 229376
verbose:socket:buffer: New client receive buffer size is smaller than original!
socket:buffer: client receive buffer not valid or not specified; using OS default(229376)
trace: netsnmp_udp_transport(): snmpUDPDomain.c, 744:
netsnmp_udp: client open UDP: [10.152.143.130]:161->[0.0.0.0]
trace: snmp_sess_add_ex(): snmp_api.c, 1664:
snmp_sess_add: fd 3
trace: _callback_lock(): callback.c, 130:
9:callback:lock: locked (LIB,SESSION_INIT)
trace: snmp_call_callbacks(): callback.c, 322:
callback: START calling callbacks for maj=0 min=5
trace: snmp_call_callbacks(): callback.c, 336:
callback: calling a callback for maj=0 min=5
trace: snmp_call_callbacks(): callback.c, 348:
callback: END calling callbacks for maj=0 min=5 (1 called)
trace: _callback_unlock(): callback.c, 164:
9:callback:lock: unlocked (LIB,SESSION_INIT)
trace: _snmp_build(): snmp_api.c, 3081:
snmp_send: Building SNMPv2 message...
trace: _snmp_build(): snmp_api.c, 3084:
dumph_send: GETNEXT
trace: snmp_pdu_realloc_rbuild(): snmp_api.c, 3452:
snmp_pdu_realloc_rbuild: starting
trace: snmp_pdu_realloc_rbuild(): snmp_api.c, 3467:
dumph_send: VarBind
trace: snmp_realloc_rbuild_var_op(): snmp.c, 341:
dumph_send: Value
dumpx_send: 05 00
dumpv_send: NULL
trace: snmp_realloc_rbuild_var_op(): snmp.c, 442:
dumph_send: Name
dumpx_send: 06 07 2B 06 01 02 01 01 01
dumpv_send: ObjID: SNMPv2-MIB::sysDescr
trace: snmp_pdu_realloc_rbuild(): snmp_api.c, 3535:
dumph_send: error index
dumpx_send: 02 01 00
dumpv_send: Integer: 0 (0x00)
trace: snmp_pdu_realloc_rbuild(): snmp_api.c, 3548:
dumph_send: error status
dumpx_send: 02 01 00
dumpv_send: Integer: 0 (0x00)
trace: snmp_pdu_realloc_rbuild(): snmp_api.c, 3561:
dumph_send: request_id
dumpx_send: 02 04 06 F3 57 C4
dumpv_send: Integer: 116611012 (0x6F357C4)
trace: _snmp_build(): snmp_api.c, 3090:
dumph_send: Community String
dumpx_send: 04 06 70 75 62 6C 69 63
dumpv_send: String: public
trace: _snmp_build(): snmp_api.c, 3106:
dumph_send: SNMP Version Number
dumpx_send: 02 01 01
dumpv_send: Integer: 1 (0x01)
trace: _snmp_build(): snmp_api.c, 3128:
dumph_send: SNMPv2c Message
trace: _sess_async_send(): snmp_api.c, 5129:
sess_process_packet: sending message id#450859967 reqid#116611012
trace: netsnmp_udp_send(): snmpUDPDomain.c, 299:
netsnmp_udp: send 42 bytes from 0x24ba846 to UDP: [10.152.143.130]:161->[0.0.0.0] on fd 3
trace: netsnmp_udp_sendto(): snmpUDPDomain.c, 203:
netsnmp_udp: netsnmp_udp_sendto: sending from 0.0.0.0 iface 0
trace: snmp_sess_select_info2(): snmp_api.c, 6195:
sess_select: for all sessions: 3 (to in 1367667166.302725 sec)
verbose:sess_select: timer due in 0.999960 sec
verbose:sess_select: setting timer to 0.999960 sec, clear block (was 1)
trace: _snmp_build(): snmp_api.c, 3081:
snmp_send: Building SNMPv2 message...
trace: _snmp_build(): snmp_api.c, 3084:
dumph_send: GETNEXT
trace: snmp_pdu_realloc_rbuild(): snmp_api.c, 3452:
snmp_pdu_realloc_rbuild: starting
trace: snmp_pdu_realloc_rbuild(): snmp_api.c, 3467:
dumph_send: VarBind
trace: snmp_realloc_rbuild_var_op(): snmp.c, 341:
dumph_send: Value
dumpx_send: 05 00
dumpv_send: NULL
trace: snmp_realloc_rbuild_var_op(): snmp.c, 442:
dumph_send: Name
dumpx_send: 06 07 2B 06 01 02 01 01 01
dumpv_send: ObjID: SNMPv2-MIB::sysDescr
trace: snmp_pdu_realloc_rbuild(): snmp_api.c, 3535:
dumph_send: error index
dumpx_send: 02 01 00
dumpv_send: Integer: 0 (0x00)
trace: snmp_pdu_realloc_rbuild(): snmp_api.c, 3548:
dumph_send: error status
dumpx_send: 02 01 00
dumpv_send: Integer: 0 (0x00)
trace: snmp_pdu_realloc_rbuild(): snmp_api.c, 3561:
dumph_send: request_id
dumpx_send: 02 04 06 F3 57 C4
dumpv_send: Integer: 116611012 (0x6F357C4)
trace: _snmp_build(): snmp_api.c, 3090:
dumph_send: Community String
dumpx_send: 04 06 70 75 62 6C 69 63
dumpv_send: String: public
trace: _snmp_build(): snmp_api.c, 3106:
dumph_send: SNMP Version Number
dumpx_send: 02 01 01
dumpv_send: Integer: 1 (0x01)
trace: _snmp_build(): snmp_api.c, 3128:
dumph_send: SNMPv2c Message
trace: snmp_resend_request(): snmp_api.c, 6443:
sess_process_packet: resending message id#450859968 reqid#116611012 rp_reqid#116611012 rp_msgid#450859968
trace: netsnmp_udp_send(): snmpUDPDomain.c, 299:
netsnmp_udp: send 42 bytes from 0x24ba846 to UDP: [10.152.143.130]:161->[0.0.0.0] on fd 3
trace: netsnmp_udp_sendto(): snmpUDPDomain.c, 203:
netsnmp_udp: netsnmp_udp_sendto: sending from 0.0.0.0 iface 0
trace: snmp_sess_select_info2(): snmp_api.c, 6195:
sess_select: for all sessions: 3 (to in 1367667167.303794 sec)
verbose:sess_select: timer due in 0.999958 sec
verbose:sess_select: setting timer to 0.999958 sec, clear block (was 1)
trace: _snmp_build(): snmp_api.c, 3081:
snmp_send: Building SNMPv2 message...
trace: _snmp_build(): snmp_api.c, 3084:
dumph_send: GETNEXT
trace: snmp_pdu_realloc_rbuild(): snmp_api.c, 3452:
snmp_pdu_realloc_rbuild: starting
trace: snmp_pdu_realloc_rbuild(): snmp_api.c, 3467:
dumph_send: VarBind
trace: snmp_realloc_rbuild_var_op(): snmp.c, 341:
dumph_send: Value
dumpx_send: 05 00
dumpv_send: NULL
trace: snmp_realloc_rbuild_var_op(): snmp.c, 442:
dumph_send: Name
dumpx_send: 06 07 2B 06 01 02 01 01 01
dumpv_send: ObjID: SNMPv2-MIB::sysDescr
trace: snmp_pdu_realloc_rbuild(): snmp_api.c, 3535:
dumph_send: error index
dumpx_send: 02 01 00
dumpv_send: Integer: 0 (0x00)
trace: snmp_pdu_realloc_rbuild(): snmp_api.c, 3548:
dumph_send: error status
dumpx_send: 02 01 00
dumpv_send: Integer: 0 (0x00)
trace: snmp_pdu_realloc_rbuild(): snmp_api.c, 3561:
dumph_send: request_id
dumpx_send: 02 04 06 F3 57 C4
dumpv_send: Integer: 116611012 (0x6F357C4)
trace: _snmp_build(): snmp_api.c, 3090:
dumph_send: Community String
dumpx_send: 04 06 70 75 62 6C 69 63
dumpv_send: String: public
trace: _snmp_build(): snmp_api.c, 3106:
dumph_send: SNMP Version Number
dumpx_send: 02 01 01
dumpv_send: Integer: 1 (0x01)
trace: _snmp_build(): snmp_api.c, 3128:
dumph_send: SNMPv2c Message
trace: snmp_resend_request(): snmp_api.c, 6443:
sess_process_packet: resending message id#450859969 reqid#116611012 rp_reqid#116611012 rp_msgid#450859969
trace: netsnmp_udp_send(): snmpUDPDomain.c, 299:
netsnmp_udp: send 42 bytes from 0x24ba846 to UDP: [10.152.143.130]:161->[0.0.0.0] on fd 3
trace: netsnmp_udp_sendto(): snmpUDPDomain.c, 203:
netsnmp_udp: netsnmp_udp_sendto: sending from 0.0.0.0 iface 0
trace: snmp_sess_select_info2(): snmp_api.c, 6195:
sess_select: for all sessions: 3 (to in 1367667168.304834 sec)
verbose:sess_select: timer due in 0.999957 sec
verbose:sess_select: setting timer to 0.999957 sec, clear block (was 1)
trace: _snmp_build(): snmp_api.c, 3081:
snmp_send: Building SNMPv2 message...
trace: _snmp_build(): snmp_api.c, 3084:
dumph_send: GETNEXT
trace: snmp_pdu_realloc_rbuild(): snmp_api.c, 3452:
snmp_pdu_realloc_rbuild: starting
trace: snmp_pdu_realloc_rbuild(): snmp_api.c, 3467:
dumph_send: VarBind
trace: snmp_realloc_rbuild_var_op(): snmp.c, 341:
dumph_send: Value
dumpx_send: 05 00
dumpv_send: NULL
trace: snmp_realloc_rbuild_var_op(): snmp.c, 442:
dumph_send: Name
dumpx_send: 06 07 2B 06 01 02 01 01 01
dumpv_send: ObjID: SNMPv2-MIB::sysDescr
trace: snmp_pdu_realloc_rbuild(): snmp_api.c, 3535:
dumph_send: error index
dumpx_send: 02 01 00
dumpv_send: Integer: 0 (0x00)
trace: snmp_pdu_realloc_rbuild(): snmp_api.c, 3548:
dumph_send: error status
dumpx_send: 02 01 00
dumpv_send: Integer: 0 (0x00)
trace: snmp_pdu_realloc_rbuild(): snmp_api.c, 3561:
dumph_send: request_id
dumpx_send: 02 04 06 F3 57 C4
dumpv_send: Integer: 116611012 (0x6F357C4)
trace: _snmp_build(): snmp_api.c, 3090:
dumph_send: Community String
dumpx_send: 04 06 70 75 62 6C 69 63
dumpv_send: String: public
trace: _snmp_build(): snmp_api.c, 3106:
dumph_send: SNMP Version Number
dumpx_send: 02 01 01
dumpv_send: Integer: 1 (0x01)
trace: _snmp_build(): snmp_api.c, 3128:
dumph_send: SNMPv2c Message
trace: snmp_resend_request(): snmp_api.c, 6443:
sess_process_packet: resending message id#450859970 reqid#116611012 rp_reqid#116611012 rp_msgid#450859970
trace: netsnmp_udp_send(): snmpUDPDomain.c, 299:
netsnmp_udp: send 42 bytes from 0x24ba846 to UDP: [10.152.143.130]:161->[0.0.0.0] on fd 3
trace: netsnmp_udp_sendto(): snmpUDPDomain.c, 203:
netsnmp_udp: netsnmp_udp_sendto: sending from 0.0.0.0 iface 0
trace: snmp_sess_select_info2(): snmp_api.c, 6195:
sess_select: for all sessions: 3 (to in 1367667169.305807 sec)
verbose:sess_select: timer due in 0.999956 sec
verbose:sess_select: setting timer to 0.999956 sec, clear block (was 1)
trace: _snmp_build(): snmp_api.c, 3081:
snmp_send: Building SNMPv2 message...
trace: _snmp_build(): snmp_api.c, 3084:
dumph_send: GETNEXT
trace: snmp_pdu_realloc_rbuild(): snmp_api.c, 3452:
snmp_pdu_realloc_rbuild: starting
trace: snmp_pdu_realloc_rbuild(): snmp_api.c, 3467:
dumph_send: VarBind
trace: snmp_realloc_rbuild_var_op(): snmp.c, 341:
dumph_send: Value
dumpx_send: 05 00
dumpv_send: NULL
trace: snmp_realloc_rbuild_var_op(): snmp.c, 442:
dumph_send: Name
dumpx_send: 06 07 2B 06 01 02 01 01 01
dumpv_send: ObjID: SNMPv2-MIB::sysDescr
trace: snmp_pdu_realloc_rbuild(): snmp_api.c, 3535:
dumph_send: error index
dumpx_send: 02 01 00
dumpv_send: Integer: 0 (0x00)
trace: snmp_pdu_realloc_rbuild(): snmp_api.c, 3548:
dumph_send: error status
dumpx_send: 02 01 00
dumpv_send: Integer: 0 (0x00)
trace: snmp_pdu_realloc_rbuild(): snmp_api.c, 3561:
dumph_send: request_id
dumpx_send: 02 04 06 F3 57 C4
dumpv_send: Integer: 116611012 (0x6F357C4)
trace: _snmp_build(): snmp_api.c, 3090:
dumph_send: Community String
dumpx_send: 04 06 70 75 62 6C 69 63
dumpv_send: String: public
trace: _snmp_build(): snmp_api.c, 3106:
dumph_send: SNMP Version Number
dumpx_send: 02 01 01
dumpv_send: Integer: 1 (0x01)
trace: _snmp_build(): snmp_api.c, 3128:
dumph_send: SNMPv2c Message
trace: snmp_resend_request(): snmp_api.c, 6443:
sess_process_packet: resending message id#450859971 reqid#116611012 rp_reqid#116611012 rp_msgid#450859971
trace: netsnmp_udp_send(): snmpUDPDomain.c, 299:
netsnmp_udp: send 42 bytes from 0x24ba846 to UDP: [10.152.143.130]:161->[0.0.0.0] on fd 3
trace: netsnmp_udp_sendto(): snmpUDPDomain.c, 203:
netsnmp_udp: netsnmp_udp_sendto: sending from 0.0.0.0 iface 0
trace: snmp_sess_select_info2(): snmp_api.c, 6195:
sess_select: for all sessions: 3 (to in 1367667170.344854 sec)
verbose:sess_select: timer due in 0.999959 sec
verbose:sess_select: setting timer to 0.999959 sec, clear block (was 1)
trace: _snmp_build(): snmp_api.c, 3081:
snmp_send: Building SNMPv2 message...
trace: _snmp_build(): snmp_api.c, 3084:
dumph_send: GETNEXT
trace: snmp_pdu_realloc_rbuild(): snmp_api.c, 3452:
snmp_pdu_realloc_rbuild: starting
trace: snmp_pdu_realloc_rbuild(): snmp_api.c, 3467:
dumph_send: VarBind
trace: snmp_realloc_rbuild_var_op(): snmp.c, 341:
dumph_send: Value
dumpx_send: 05 00
dumpv_send: NULL
trace: snmp_realloc_rbuild_var_op(): snmp.c, 442:
dumph_send: Name
dumpx_send: 06 07 2B 06 01 02 01 01 01
dumpv_send: ObjID: SNMPv2-MIB::sysDescr
trace: snmp_pdu_realloc_rbuild(): snmp_api.c, 3535:
dumph_send: error index
dumpx_send: 02 01 00
dumpv_send: Integer: 0 (0x00)
trace: snmp_pdu_realloc_rbuild(): snmp_api.c, 3548:
dumph_send: error status
dumpx_send: 02 01 00
dumpv_send: Integer: 0 (0x00)
trace: snmp_pdu_realloc_rbuild(): snmp_api.c, 3561:
dumph_send: request_id
dumpx_send: 02 04 06 F3 57 C4
dumpv_send: Integer: 116611012 (0x6F357C4)
trace: _snmp_build(): snmp_api.c, 3090:
dumph_send: Community String
dumpx_send: 04 06 70 75 62 6C 69 63
dumpv_send: String: public
trace: _snmp_build(): snmp_api.c, 3106:
dumph_send: SNMP Version Number
dumpx_send: 02 01 01
dumpv_send: Integer: 1 (0x01)
trace: _snmp_build(): snmp_api.c, 3128:
dumph_send: SNMPv2c Message
trace: snmp_resend_request(): snmp_api.c, 6443:
sess_process_packet: resending message id#450859972 reqid#116611012 rp_reqid#116611012 rp_msgid#450859972
trace: netsnmp_udp_send(): snmpUDPDomain.c, 299:
netsnmp_udp: send 42 bytes from 0x24ba846 to UDP: [10.152.143.130]:161->[0.0.0.0] on fd 3
trace: netsnmp_udp_sendto(): snmpUDPDomain.c, 203:
netsnmp_udp: netsnmp_udp_sendto: sending from 0.0.0.0 iface 0
trace: snmp_sess_select_info2(): snmp_api.c, 6195:
sess_select: for all sessions: 3 (to in 1367667171.345775 sec)
verbose:sess_select: timer due in 0.999958 sec
verbose:sess_select: setting timer to 0.999958 sec, clear block (was 1)
trace: snmp_synch_input(): snmp_client.c, 180:
snmp_synch: Response (ReqID: 116611012 - Cmd 161)
Timeout: No Response from ec2-54-234-96-235.compute-1.amazonaws.com
[root@domU-12-31-39-0A-98-02 snmp]#

Second Machine:
[root@ip-10-152-143-130 snmp]# service iptables status
Table: filter
Chain INPUT (policy ACCEPT)
num target prot opt source destination
1 ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 state NEW tcp dpt:8080
2 ACCEPT udp -- 0.0.0.0/0 0.0.0.0/0 state NEW udp dpt:514
3 ACCEPT udp -- 0.0.0.0/0 0.0.0.0/0 state NEW udp dpt:162

Chain FORWARD (policy ACCEPT)
num target prot opt source destination

Chain OUTPUT (policy ACCEPT)
num target prot opt source destination
1 ACCEPT udp -- 0.0.0.0/0 0.0.0.0/0 state NEW udp dpt:162

[root@ip-10-152-143-130 snmp]# ping -c 3 ec2-107-22-38-45.compute-1.amazonaws.com
PING ec2-107-22-38-45.compute-1.amazonaws.com (10.211.155.240) 56(84) bytes of data.
64 bytes from domU-12-31-39-0A-98-02.compute-1.internal (10.211.155.240): icmp_seq=1 ttl=56 time=1.84 ms
64 bytes from domU-12-31-39-0A-98-02.compute-1.internal (10.211.155.240): icmp_seq=2 ttl=56 time=2.03 ms
64 bytes from domU-12-31-39-0A-98-02.compute-1.internal (10.211.155.240): icmp_seq=3 ttl=56 time=1.94 ms

--- ec2-107-22-38-45.compute-1.amazonaws.com ping statistics ---
3 packets transmitted, 3 received, 0% packet loss, time 1999ms
rtt min/avg/max/mdev = 1.849/1.940/2.033/0.090 ms
[root@ip-10-152-143-130 snmp]# route -n
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
10.152.143.128 0.0.0.0 255.255.255.192 U 0 0 0 eth0
169.254.0.0 0.0.0.0 255.255.0.0 U 0 0 0 eth0
0.0.0.0 10.152.143.129 0.0.0.0 UG 0 0 0 eth0
[root@ip-10-152-143-130 snmp]# traceroute ec2-107-22-38-45.compute-1.amazonaws.com
traceroute to ec2-107-22-38-45.compute-1.amazonaws.com (10.211.155.240), 30 hops max, 40 byte packets
1 * * *
2 * * *
3 * * *
4 * * *
5 * * *
6 * * *
7 * * *
8 * * *
9 * * *
10 * * *
11 * * *
12 * * *
13 * * *
14 * * *
15 * * *
16 * * *
17 * * *
18 * * *
19 * * *
20 * * *
21 * * *
22 * * *
23 * * *
24 * * *
25 * * *
26 * * *
27 * * *
28 * * *
29 * * *
30 * * *
[root@ip-10-152-143-130 snmp]# snmpwalk -v 2c -c public -DALL ec2-107-22-38-45.compute-1.amazonaws.com .1.3.6.1.2.1.1.1
No log handling enabled - turning on stderr logging
trace: snmp_parse_args(): snmp_parse_args.c, 613:
snmp_parse_args: finished: 6/8
trace: netsnmp_ds_set_string(): default_store.c, 283:
netsnmp_ds_set_string: Setting LIB:6 = "snmpapp"
container_registry: registered container factory binary_array (binary_array)
container_registry: registered container factory sorted_singly_linked_list (sorted_singly_linked_list)
container_registry: registered container factory unsorted_singly_linked_list (unsorted_singly_linked_list-lifo)
container_registry: registered container factory lifo (unsorted_singly_linked_list-lifo)
container_registry: registered container factory fifo (unsorted_singly_linked_list-fifo)
trace: netsnmp_container_get_null_factory(): container_null.c, 173:
...
...
Timeout: No Response from ec2-107-22-38-45.compute-1.amazonaws.com
[root@ip-10-152-143-130 snmp]#

I don't know if the choice for these IP addresses was by design but this isn't going to work as there is no router in the middle that knows how to route between the disparate 10.211.154.0 and 10.152.143.0 private LAN ranges. If you would have an Amazon VPC you would choose a bigger range and then set the CIDR mask as big enough to encompass both networks and drop virtual hardware in the middle as router. (Note I'm not RouterGod though ;-p)

The easiest, quickest solution, as I said in my initial reply, IMHO is to connect these machines via their public IP addresses.