facha's questions

I have some zombie processes on my system. I've killed the parent of those zombies hoping init will take over and free up the resources (lots of sockets in CLOSE_WAIT). However init is not removing those proceses from the system:

#ps ax
...
17051 ?        Zl   8498:24 [impalad] <defunct>
...

# ps -o ppid= -p 17051
    1

Is there a way to remove the zombies without rebooting?

UPDATE:

I've tried kill -s SIGCHLD 1. It didn't help.

I'm looking for a lightweight task queue manager for linux. The way I see it, different processes should be submitting task to the queue, the queue manager would execute them one by one in order of submission.

Is there any software that does that. I've looked at celery and geaman, but they are too heavy for the task I'm at.

smartd has detected a bad block on my hard drive and I'd like to know what file does that block belong to. I have ext3 filesystem on a logical volume. Google gave me a lot of tutorials (like this one: http://www.vanderzee.org/bad_blocks_howto) of how to find file by block number when filesystem is created directly on hdd block device. None of them mentions LVM. Is there a way to find file by block number in my case?

I can't reboot or shutdown the guest vm from the host machine

virsh -c qemu:///system reboot vm1
Domain vm1 is being rebooted

After executing this, nothing happens. The guest vm keeps working.

Could anyone help? I'm using CentOS 6.3, libvirtd, kvm. The guest vm is also CentOS 6.3

I have ftp access to a server I do not control. I'd like to start sending archives of my server's FS to that ftp. The problem is I don't have enough free space on my system to create a backup archive first (and store it on my fs) and then send it to ftp. So I'm wondering if it is possible to do something like this:

tar -jcpvf - / | ftp-put ftp://user:pass@host/file.tbz 

Normally there is no problem doing it over ssh, but in this case I only have ftp available.

Can 32-bit ASN be dangerous/tricky in any way? We are currently implanting BGP in our network. One of the uplinks has emphasized that their ASN is 32-bit. Ours is 32-bits as well. What is it I should be paying attention to when dealing with 32-bit ASNs? I've already checked that our router's software supports it. Is there anything else to be checked?

I've got a problem with TP-Link soho routers. The DNS forwarder of those routers tends to ignore the DNS servers obtained by DHCP and instead tries sending all DNS requests to this strange IP: 1.0.0.19? That IP doesn't respond.

Has anyone else seen that happen?

I have a problem with an snmpwalk query returning snmp variables in a non-uniform way:

.1.3.6.1.2.1.10.127.1.3.3.1.2.215 -> Hex-STRING: 24 37 4C 0C 65 0E 
.1.3.6.1.2.1.10.127.1.3.3.1.2.216 -> Hex-STRING: 24 37 4C 0B A2 DA 
.1.3.6.1.2.1.10.127.1.3.3.1.2.217 -> STRING: "$7L
                                                 f:"
.1.3.6.1.2.1.10.127.1.3.3.1.2.218 -> STRING: "$7L
                                                 k2"

As you can see, some variables are of a STRING type, others are Hex-STRING. So, I'm trying to write a simple MIB to force them all come out as Hex-STRING. This is where I've gotten so far:

TEST-MIB DEFINITIONS ::= BEGIN

PhysAddress ::= TEXTUAL-CONVENTION
    DISPLAY-HINT "1x:"
    STATUS       current
    SYNTAX       OCTET STRING

test OBJECT-TYPE
    SYNTAX PhysAddresss
    MAX-ACCESS    read-only
    STATUS        current
    ::= { 1 3 6 1 2 1 10 127 1 3 3 1 2 }

END

However, snmpwalk doesn't seem to notice my textual convention (even though the "test" variable is being recognized). I still get a mixture of STIRNGs and Hex-STRINGs. Where is my mistake?

snmpwalk -v2c -cpublic 192.168.1.2 TEST-MIB::test
...
TEST-MIB::test.216 = Hex-STRING: 24 37 4C 0B A2 DA 
TEST-MIB::test.217 = STRING: "$7L
                                 f:"

I have nginx working as a frontend to tornado (which is running an app based on Flask framework). Nginx is running on 8080 port. However when Flask generates a "301 redirect" it does not take into account the 8080 port. I get a redirect to 80 port, where I have nothing listening.

This is my nginx config for the site:

server {
    listen 8080;
    server_name localhost;

    location ~* ^.+.(jpg|jpeg|gif|png|ico|css|zip|tgz|gz|rar|bz2|doc|xls|exe|pdf|ppt|txt|tar|mid|midi|wav|bmp|rtf|js)$ {
        expires off;
    }
    location / {
        proxy_set_header X-Real-IP  $remote_addr;
        proxy_set_header Host $host;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header X-Forwarded-Port 8080;
        proxy_pass http://127.0.0.1:5000;
    }
}

Is there a way to correct the problem?

I'm trying to do translate a web page automatically with a shell script. Here is the interesting part:

wget http://www.google.com/translate?langpair=en%7Ces&u=http%3A%2F%2Fasdf.com

I'm getting the "ERROR 403: Forbidden" even though I can get the translation when using this URL in browser. Could someone explain what's going on? Why google forbids the "translator" usage from shell script? Do they monitor user agent or they have another way to tell if you are a browser or not?

If someone knows another way to do it (for example if there is a console non-interactive browser that would fetch that URL or, perhaps there is another online translation tool I'm not aware of) please let me know.

I'm wondering what is the correct way to count how many IPs are in use in my network according to the dhcpd process.

Is it just a matter of counting "binding state active" lines in dhcpd.leases file? Or it is something more complicated?

Thanks in advance.

I'd like to setup postfix as an MTA for 2 domains, about 10 users each. I'm a bit confused with the documentation. Postfix has so many options for mail delivery. I'd like to have a simple file where I would store all the email addresses (and possibly their corresponding mailboxes). I wouldn't like neither system's passswd file nor mysql to be used for storing email users. What parts of documentation I should be focused on?

I'm seeking advice about which technology to use to classify packets for shaping in traffic control (tc). I've found at least 3 that could be used:

• iptables MARK
• iptables CLASSIFY
• tc filter

Which one should I use? Is there one that is better than others?

I have a CentOS server with isc dhcpd and apache 2 webserver running. A couple of minutes ago I have tried to restart apache:

/etc/init.d/httpd restart

Restart has failed with:

Starting httpd: (98)Address already in use: make_sock: could not bind to address [::]:80
(98)Address already in use: make_sock: could not bind to address 0.0.0.0:80
no listening sockets available, shutting down

Apache was complaining that the 80 port has been already taken. I've executed

netstat -ntap

to see who is listening on 80 port. And it was dhcpd. Since before restart apache and dhcpd were running simultaneously I guess what has happened was that just after apache was off, dhcp has noticed that 80 port is free and started listening it. Does anybody know in what cases dhcpd would do it and why? I've tried to reproduce that a couple of times but with no luck.

I have a linux-based bridge. I'd like to count how much traffic does every IP that passes throug generates. In other words I'd like to get a file like this:

src_IP  dst_IP  pkt_size
1.1.1.1 2.2.2.2 12304
3.3.3.3 4.4.4.4 430
....

Is there a tool to do it under linux?

I've done some search on ulog, however both "accounting daemon" projects seem to be abandoned (their webpages do not work). Capturing traffic with tcpdump and then analyzing the dump could be an option, however I can't see how can I get the packet size from the dump.

Please, let me know if there is a way to do it.

I'm looking for a lightweight dns server that could resolve any possible domain name to a specific IP address (e.g 192.168.1.1).

. -> 192.168.1.1
com -> 192.168.1.1
org -> 192.168.1.1
google.com -> 192.168.1.1
yahoo.com  -> 192.168.1.1
....
anypossibledomainname.evenifitdoesntexist.blah -> 192.168.1.1

Thanks in advance.

I'm struggling all morning to make php work with an sqlite database. Here is a piece of php code that I try to execute:

#less /var/www/html/test.php

<?php
    $db=new PDO("sqlite:/var/www/test.sql");
    $sql = "insert into test (login,pass) values ('login','pass');";
    $db->exec($sql);
?>

Here is how I've done tests:

# sqlite3 /var/www/test.sql
sqlite> create table test (login varchar,pass varchar);
#chown apache:apache /var/www/test.sql
#chmod 644 /var/www/test.sql

Here is the stuff that drives me mad: When I execute from command line:

#php test.php

everything goes well. Sql is being executed and I can see a new row appear in the database.

When I execute the same script from a browser - sql is not being executed. I don't get a new row in the database. There are no errors in the apache log file.

Please, help

UPDATE:

Ok, I've got the answer. It looks like sqlite is trying to create a new -journal file on "INSERT" query. strace rocks:

open("/var/www/test.sql-journal", O_RDWR|O_CREAT|O_EXCL|O_LARGEFILE, 0644) = -1 EACCES (Permission denied)

So, I had to move sqlite database to a directory, apache could write to.

I've setup a drbd replication between two machines and used a drbd block device as storage for a kvm machine. Everything is running well. However I'm in doubt if this setup is ok to use. From what I've read so far on the internet, people tend to use drbd->ocfs2->qcow2_file as storage for their virtual machines.

I have a linux based traffic shaper (iptables + tc htb policy). It works in bridge mode. Shapes traffic based on IPs and ports (there are about 100 rules in the "mangle" chain of iptables). Right now its throughoutput is about 100 mb/s (I don't remember pps, there are about 800 users in the network). Just was wondering - when I will hit the limit. How much traffic could a linux-based shaper possibly get throuhg it. If you have one under heavy load, please could you write what machine you use and what load there is. Or if you have any other info about the subj, please write as well.

Thanks in advance.

I have a huge pcap file (generated by tcpdump). When I try to open it in wireshark, the program just gets unresponsive. Is there a way to split a file in set of smaller ones to open them one by one? The traffic captured in a file is generated by two programs on two servers, so I can't split the file using tcpdump 'host' or 'port' filters. I've also tried linux 'split' command :-) but with no luck. Wireshark wouldn't recognize the format.