Hi,
I succeded in sending the Informs from pre-defined ports.
I did not finish my implementation, but I want to discuss my intention
and varify it is ok.
Design:
------------
I remind you that I wanted the informs to be send from fixed ports so I
can configure my Firewall
to open these UDP ports only (for Infrom ACKs).
I intened to define a range of fixed ports (say 6070-6072, or probably
configurable through the snmpd.conf file),
and that for each target (In the SnmpTargetMib, that is configured to
receive an Inform) the inform would be sent from a specific port.
For example:
-------------------
for the first target (which receive an Inform) it will be sent from the
6070 port.
for the second target (which receive an Inform) it will be sent from the
6071 port.
...
(assuming number of target is restricted to the size of the fixed-port
range)
The implementation:
------------------------------
Files changed:
1) target.c - Add mechanism for assigning client addresses (via the
NETSNMP_DS_LIB_CLIENT_ADDR attribute in the DataStore) for each new
target session.
2) snmpUDPDomain.c - Comment out a line which overrides the port in
NETSNMP_DS_LIB_CLIENT_ADDR and sets it to zero
//client_addr.sin_port = 0;
Questions:
-----------------
1) What are the implications of commenting out the mentoioned line from
snmpUDPDomain.c ?
netsnmp_udp_transport(...)
...
if (local) {
... } else {
client_socket = netsnmp_ds_get_string(NETSNMP_DS_LIBRARY_ID,
NETSNMP_DS_LIB_CLIENT_ADDR);
if (client_socket) {
struct sockaddr_in client_addr;
netsnmp_sockaddr_in( &client_addr, client_socket, 0);
//--------------------------
//client_addr.sin_port = 0;
// ----------------------------
bind(t->sock, (struct sockaddr *)&client_addr,
sizeof(struct sockaddr));
}
2) Does this solution make sense? does it qualify submitting to the
official net-snmp version?
Thanks,
Erez.
-----Original Message-----
From: Makavy, Erez (Erez)
Sent: Sunday, May 20, 2007 3:00 PM
To: 'Dave Shield'
Cc: net-snmp-coders@lists.sourceforge.net
Subject: RE: Sending Informs with fixed source ports
I tried binding to the IP address of eth0. The trap is sent but not from
my specified port:
tcpdump:
------------
14:56:52.983519 IP 135.64.102.110.32797 > 135.64.102.136.snmptrap: F=ar
U=usr1 [|snmp][|snmp]
14:57:11.876272 IP 135.64.102.110.32797 > 135.64.102.136.snmptrap: F=ar
U=usr1 [|snmp][|snmp]
14:57:43.656022 IP 135.64.102.110.32797 > 135.64.102.136.snmptrap: F=ar
U=usr1 [|snmp][|snmp]
14:57:49.571344 IP 135.64.102.110.32803 > 135.64.102.136.snmptrap: F=ar
U=usr1 [|snmp][|snmp]
14:57:49.696096 IP 135.64.102.110.32803 > 135.64.102.136.snmptrap: F=ar
U=usr1 [|snmp][|snmp]
14:57:58.590007 IP 135.64.102.110.32803 > 135.64.102.136.snmptrap: F=ar
U=usr1 [|snmp][|snmp]
snmpd logging:
---------------------
netsnmp_udp: recvfrom fd 6 got 39 bytes (from UDP:
[135.64.102.136]:1657) Connection from UDP: [135.64.102.136]:1657
netsnmp_udp_getSecName: no com2sec entries
send_notifications: starting: pdu=94a2170, vars=0
target_sessions: looking for: inform
target_sessions: for: 0=inform
target_sessions: found one: inform
netsnmp_udp: open remote UDP: [135.64.102.136]:162:41472
netsnmp_sockaddr_in: addr 0xbfdb9db0, peername "135.64.102.110:6666"
netsnmp_sockaddr_in: port number suffix :6666
netsnmp_sockaddr_in: IP address
netsnmp_sockaddr_in: return { AF_INET, 135.64.102.110:6666 }
netsnmp_udp: Binded to client_socket
target_sessions: to: UDP: [135.64.102.136]:162
target_sessions: timeout: 1500 -> 1500000
target_sessions: setting SNMP_FLAG_DONT_PROB for snmp_add, and
EIDtarget_sessions: looking for: trap
target_sessions: for: 0=trap
send_notifications: sent 0 notifications
send_notifications: starting: pdu=94a2208, vars=94a24f0
target_sessions: looking for: inform
target_sessions: for: 0=inform
target_sessions: found one: inform
send_notifications: checking filters...
send_notifications: no matching profile
netsnmp_udp: send 168 bytes from 0x94a3870 to UDP: [135.64.102.136]:162
on fd 7
target_sessions: looking for: trap
target_sessions: for: 0=trap
send_notifications: sent 1 notifications
netsnmp_udp: recvfrom fd 7 got 168 bytes (from UDP:
[135.64.102.136]:1658)
Any ideas?
Thanks,
Erez.
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
Behalf Of Dave Shield
Sent: Saturday, May 19, 2007 12:41 AM
To: Makavy, Erez (Erez)
Cc: net-snmp-coders@lists.sourceforge.net
Subject: Re: Sending Informs with fixed source ports
On 08/05/07, Makavy, Erez (Erez) <[EMAIL PROTECTED]> wrote:
> I tried adding this line to target.c:get_target_sessoin():
>
> netsnmp_ds_set_string(NETSNMP_DS_LIBRARY_ID,
> NETSNMP_DS_LIB_CLIENT_ADDR, "localhost:6666");
> I get an error, you can see in the debug logs:
> ----------------------------------------------------
> netsnmp_sockaddr_in: addr 0xbfe7c040, peername "localhost:6666"
> netsnmp_sockaddr_in: port number suffix :6666
> netsnmp_sockaddr_in: hostname (resolved okay)
> netsnmp_sockaddr_in: return { AF_INET, 127.0.0.1:6666 }
:
> netsnmp_udp: send 165 bytes from 0x8f52d83 to UDP:
> [135.64.102.136]:162 on fd 7
> netsnmp_udp: sendto error, rc -1 (errno 22)
> snmpd: send_trap: Failure in sendto (Invalid argument)
That probably makes sense.
I suspect that there may not be a route from the loopback interface to
that IP address. In order to send traffic to that system, you'd have to
use a source address that's on the same network as either the
destination system, or else a suitable gateway.
Using "localhost" as the source won't qualify.
Dave
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