From a NodeJS script, using sed, how to replace string with multiple line string

Question

I am doing a script that add a sample of /etc/iptables.rules file on my server.

/etc/iptables.rules

*filter

-P INPUT ACCEPT
-P FORWARD ACCEPT
-P OUTPUT ACCEPT
-N DOCKER
${DROP_INTERFACE}
-A FORWARD -o docker0 -j DOCKER
-A FORWARD -o docker0 -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
-A FORWARD -i docker0 ! -o docker0 -j ACCEPT
-A FORWARD -i docker0 -o docker0 -j ACCEPT

COMMIT

Then, the node JS script add after ${DROP_INTERFACE} multiple lines then remove the tag :

app.js

// retrieve public interface in order to restrict access
var names = _.pluck(results.publicIfaceList, 'name');
var dropInterface = []; // eg : ['eth1', 'eth2"]
for(var i = 0; i < names.length; i++){
    // add a new DROP rule
    dropInterface.push("-A FORWARD -i "+names[i]+" -j DROP");
}

// for each rules
async.eachSeries(dropInterface, function iterator(item, next){
    // add a line after ${DROP_INTERFACE}
    var cmd = "sed -i '/${DROP_INTERFACE}/a " + item + "' " + FirewallConstants.IPTABLES_RULES;
    bash.execute(cmd, function(output){
        next();
    }); 
}, function done(){
    // remove the line with ${DROP_INTERFACE}
    var cmd = "sed -i '/${DROP_INTERFACE}/d' " + FirewallConstants.IPTABLES_RULES;
    bash.execute(cmd, function(output){
        cb();
    });
});

I have also tried to replace the tag with multiple lines at once :

var names = _.pluck(results.publicIfaceList, 'name');
var dropInterface = [];
for(var i = 0; i < names.length; i++){
    dropInterface.push("-A FORWARD -i "+names[i]+" -j DROP");
}
var cmd = "sed -i '/${DROP_INTERFACE}/c\\"+dropInterface.join('\n')+"' /etc/iptables.rules";
bash.execute(cmd, function (output){
    cb();
});

None of my methods worked, I had different errors like :

Doesn't replace the string at all
Tested with !DROP_INTERFACE instead of ${DROP_INTERFACE}, only the "!" character was removed.
${DROP_INTERFACE} is a wrong occurrence (or something similar).

Does anyone has a working example of a multiple lines text insertion using sed from a nodejs script ?

The main goal is to drop access from this interface to any services listening on public interfaces (0.0.0.0).

What do you mean ? it is node js. can you provide an example ? — Dimitri Kopriwa, Jan 23 '16 at 19:10
http://stackoverflow.com/questions/14177087/replace-a-string-in-a-file-with-nodejs — hek2mgl, Jan 23 '16 at 19:12
I think I didn't do it nodejs style unconsciously, it's originally a bash converted script. Thanks, I am having a look at your link — Dimitri Kopriwa, Jan 23 '16 at 19:15

score 1 · Answer 1 · answered Jan 23 '16 at 21:16

Worked for me :

        var names = _.pluck(results.publicIfaceList, 'name');
        var dropInterface = [];
        for(var i = 0; i < names.length; i++){
            dropInterface.push("-A FORWARD -i "+names[i]+" -j DROP");
        }

        fs.readFile(FirewallConstants.IPTABLES_RULES, 'utf8', function (err,data) {
            if (err) {
                cb(err);
                return;
            }

            var result = data.replace("${DROP_INTERFACE}", dropInterface.join('\n'));
            fs.writeFile(FirewallConstants.IPTABLES_RULES, result, 'utf8', function (err) {
                cb(err);
            });
        });

From a NodeJS script, using sed, how to replace string with multiple line string

1 Answers1