Check ip6tables_rules_for_open_ports.sh incorrectly parses output of `ip6tables -L INPUT -v -n`

[Przemyslaw Hausman]

usg version: 22.04.6

Check /usr/share/ubuntu-scap-security-guides/1/benchmarks/ubuntu2204/checks/sce/ip6tables_rules_for_open_ports.sh incorrectly parses the output of `ip6tables -L INPUT -v -n`.

As a result, ip6tables_rules_for_open_ports.sh check returns incorrect return value, marking the rule failed.

I have the system with the following opened ports:

```
# ss -6tuln
Netid State Recv-Q Send-Q Local Address:Port Peer Address:Port Process
udp UNCONN 0 0 [fc00:722d:3a95:450e:f816:3eff:fe96:aedf]:5555 [::]:*
udp UNCONN 0 0 [::]:6081 [::]:*
tcp LISTEN 0 1024 [::1]:11211 [::]:*
tcp LISTEN 0 100 [::1]:25 [::]:*
tcp LISTEN 0 128 [::]:22 [::]:*
tcp LISTEN 0 511 *:80 *:*
tcp LISTEN 0 511 *:443 *:*
tcp LISTEN 0 511 *:9856 *:*
tcp LISTEN 0 511 *:9866 *:*
tcp LISTEN 0 4096 *:9876 *:*
```

On this system, running the check fails because:

```
# ss -6tuln | awk '($5!~/%lo:/ && $5!~/127.0.0.1:/ && $5!~/::1/) {split($5, a, ":"); print a[2]}i' | sor
t | uniq

443
722d <---- THIS IS INCORRECT
80
9856
9866
9876
```

[Miha Purg (mihap)]

Hi Przemyslaw, thanks for reporting the bug!

Can you confirm that this gives the expected output:

# ss -6tulnH | awk '($5!~/::1/) {n=split($5, a, ":"); print a[n]}' | sort -u

[Miha Purg (mihap)]

Fix will be included in the next release of usg for jammy (22.04.7).

[Przemyslaw Hausman (phausman)]

Hi @mihap, thank you for working in this! Yes, the fix you mentioned in #1 seems to be working correctly. Thanks again!