We currently have a server that blocks all connections using iptables, and we have to whitelist an IP expressly in order to be able to access the server remotely.
Essentially, the first rule allows the whitelisted IPs (including localhost interface) to progress further to the other chains on the firewall, while rejecting any IP that is not on the list.
Is it possible for an attacker to somehow circumvent the iptables rules to gain access to the server?
Sample rules follow below:
Chain INPUT (policy DROP 0 packets, 0 bytes)
pkts bytes target prot opt in out source destination
1507K 136M ALLOW all -- * * 0.0.0.0/0 0.0.0.0/0
Chain ALLOW (1 references) pkts bytes target prot opt in out source destination 183K 36M next_chain all -- * * 198.###.##.### 0.0.0.0/0 3053K 237M ACCEPT all -- lo * 0.0.0.0/0 0.0.0.0/0 116K 5859K REJECT all -- * * 0.0.0.0/0 0.0.0.0/0 reject-with icmp-port-unreachable