AS400 systems listen for SNMP get requests on port 161 but they respond to the requestor on a random ephemeral port above 5000. This is true for all versions up to i6.1 at least.
Can SNMP listen for an SNMP response on a different port from the one it used to issue the SNMP get request? If so, how is this adjusted inside the product?
Thanks for your attention to this question.
Article Comments
from another forum we could find this
Turns out, the OS/400 implementation of SNMP, as with many things in its TCP stack, is slightly off. Our firewalls were blocking the snmp-replies. Basically, with most devices you send an SNMP-read to port 161 with a source of some random high port, and it will reply with source port 161. The iSeries, however, chooses a random source port to reply with. Fortunately, our firewall had an option for snmp for "Accept replies from any port." This solved the problem.
So the issue might be with your firewall.
The SNMP listening port probably needs not to be changed.
Jul, 2011 - Permalink
from another forum we could find this
Turns out, the OS/400 implementation of SNMP, as with many things in its TCP stack, is slightly off. Our firewalls were blocking the snmp-replies. Basically, with most devices you send an SNMP-read to port 161 with a source of some random high port, and it will reply with source port 161. The iSeries, however, chooses a random source port to reply with. Fortunately, our firewall had an option for snmp for "Accept replies from any port." This solved the problem.
So the issue might be with your firewall.
The SNMP listening port probably needs not to be changed.
Jul, 2011 - Permalink