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https://issues.apache.org/jira/browse/VCL-875?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14617171#comment-14617171
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ASF subversion and git services commented on VCL-875:
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Commit 1689723 from [~arkurth] in branch 'vcl/trunk'
[ https://svn.apache.org/r1689723 ]
VCL-875
Updated Linux.pm::enable_firewall_port to ignore existing multiport rules when
determining if adding a rule is necessary.
> Management node loses SSH access if iptables multiport rule exists
> ------------------------------------------------------------------
>
> Key: VCL-875
> URL: https://issues.apache.org/jira/browse/VCL-875
> Project: VCL
> Issue Type: Bug
> Components: vcld (backend)
> Affects Versions: 2.4.2
> Reporter: Andy Kurth
> Fix For: 2.4.3
>
>
> The 2.4.2 code handles the firewall a bit differently. It attempts to open
> up access to each of the management node's IP addresses on any port.
> Afterwards, it removes rules allowing port 22. The logic is that the
> management node can still connect via a rule allowing all ports, even if no
> specific port 22 rules exist.
> This normally works fine, but can cause the management node to get locked out.
> The old firewall code parses _iptables -L_ output and assembles a hash
> containing all of the rule information. It is checking for rules which
> contain _dpt:_ to specify a destination port. If it doesn't find this, it
> assumes the rule applies to all ports. Rules which have a _multiport_
> specification are not parsed properly. The _multiport_ is ignored and the
> code assumes the rule applies to all ports.
> When the code attempts to add the rules to allow traffic from the management
> node's addresses, it checks existing rules. If it finds one that matches,
> including any rule which matches the protocol/port that includes the scope
> argument, a new rule isn't added. This causes the management node to get
> locked out.
> Assume the code attempts to open up the MN's a.b.c.d address to any port, and
> it finds an existing rule allowing traffic from any address which has
> _multiport dports 5555,6666_. The code assumes the firewall is already open
> and doesn't add a new rule. The port 22 rules are then removed and the
> management node is locked out.
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