Thanks Chris!
I disabled the blocking rule:
# iptables -L INPUT --line-numbers
iptables -L INPUT --line-numbers
Chain INPUT (policy ACCEPT)
num target prot opt source destination
1 DROP udp -- anywhere anywhere udp dpt:161
2 ACCEPT udp -- anywhere anywhere udp dpt:161
# iptables -D INPUT 1
iptables -D INPUT 1
# iptables -L INPUT --line-numbers
iptables -L INPUT --line-numbers
Chain INPUT (policy ACCEPT)
num target prot opt source destination
1 ACCEPT udp -- anywhere anywhere udp dpt:161
#
Then I tried to disable/enable the SNMP service. However, every time I enabled it, rule 1 was somehow being recreated! I then would delete it once more, check that it has been deleted, but no connection to port 161 was available.
Trying to re-enable snmp repeats the cycle.
(BTW, I also tried activating SNMP on a DG834GT (normal router, not in bridged mode) and I could not get the SNMP cgi page. However, this router is running the older Version 1.02.09 of the firmware).
The SNMP firewall rule does not make sense to me. I mean, you would as a minimum want to access the router from its LAN address, right?
Anything else I could try?