I have a centos machine and I am trying install some dependencies using yum. When I do this I keep getting a message saying the host cannot be resolved. I was told the previous person that used the machine deployed a very restrictive firewall on it. I tried service iptables stop, but I am still having this issue. What other firewalls could be preventing me from communicating with other hosts?The firewall is setup in a way that I can only ssh into the machine through a specific machine in a given lab.Error:sudo yum install perl-XML-SimpleLoaded plugins: fastestmirror, refresh-packagekit, securityLoading mirror speeds from cached hostfile * base: centos.mirror.ndchost.com * extras: centosmirror.quintex.com * updates: centos.aol.comhttp://centos.mirror.ndchost.com/6.5/os/x86_64/repodata/repomd.xml: [Errno 14] PYCURL ERROR 6 - Couldn't resolve host 'centos.mirror.ndchost.com'Trying other mirror.http://mirror.cs.vt.edu/pub/CentOS/6.5/os/x86_64/repodata/repomd.xml: [Errno 14] PYCURL ERROR 6 - Couldn't resolve host 'mirror.cs.vt.edu'Trying other mirror.http://mirror.pac-12.org/6.5/os/x86_64/repodata/repomd.xml: [Errno 14] PYCURL ERROR 6 - Couldn't resolve host 'mirror.pac-12.org'Trying other mirror.http://mirror.rackspace.com/CentOS/6.5/os/x86_64/repodata/repomd.xml: [Errno 14] PYCURL ERROR 6 - Couldn't resolve host 'mirror.rackspace.com'Trying other mirror.http://mirror.raystedman.net/centos/6.5/os/x86_64/repodata/repomd.xml: [Errno 14] PYCURL ERROR 6 - Couldn't resolve host 'mirror.raystedman.net'Trying other mirror.http://mirror.solarvps.com/centos/6.5/os/x86_64/repodata/repomd.xml: [Errno 14] PYCURL ERROR 6 - Couldn't resolve host 'mirror.solarvps.com'Trying other mirror.http://mirror.team-cymru.org/CentOS/6.5/os/x86_64/repodata/repomd.xml: [Errno 14] PYCURL ERROR 6 - Couldn't resolve host 'mirror.team-cymru.org'Trying other mirror.http://mirrors.easynews.com//linux/centos/6.5/os/x86_64/repodata/repomd.xml: [Errno 14] PYCURL ERROR 6 - Couldn't resolve host 'mirrors.easynews.com'Trying other mirror.http://mirrors.usc.edu/pub/linux/distributions/centos/6.5/os/x86_64/repodata/repomd.xml: [Errno 14] PYCURL ERROR 6 - Couldn't resolve host 'mirrors.usc.edu'Trying other mirror.ftp://mirror.nandomedia.com/pub/CentOS/6.5/os/x86_64/repodata/repomd.xml: [Errno 14] PYCURL ERROR 6 - Couldn't resolve host 'mirror.nandomedia.com'Trying other mirror.http://centosmirror.quintex.com/6.5/extras/x86_64/repodata/repomd.xml: [Errno 14] PYCURL ERROR 6 - Couldn't resolve host 'centosmirror.quintex.com'Trying other mirror.http://mirror.beyondhosting.net/CentOS/6.5/extras/x86_64/repodata/repomd.xml: [Errno 14] PYCURL ERROR 6 - Couldn't resolve host 'mirror.beyondhosting.net'Trying other mirror.http://mirror.compevo.com/centos/6.5/extras/x86_64/repodata/repomd.xml: [Errno 14] PYCURL ERROR 6 - Couldn't resolve host 'mirror.compevo.com'Trying other mirror.http://mirror.kentdigital.net/6.5/extras/x86_64/repodata/repomd.xml: [Errno 14] PYCURL ERROR 6 - Couldn't resolve host 'mirror.kentdigital.net'Trying other mirror.http://mirror.wiredtree.com/centos/6.5/extras/x86_64/repodata/repomd.xml: [Errno 14] PYCURL ERROR 6 - Couldn't resolve host 'mirror.wiredtree.com'Trying other mirror.http://mirrors.adams.net/centos/6.5/extras/x86_64/repodata/repomd.xml: [Errno 14] PYCURL ERROR 6 - Couldn't resolve host 'mirrors.adams.net'Trying other mirror.http://mirrors.easynews.com//linux/centos/6.5/extras/x86_64/repodata/repomd.xml: [Errno 14] PYCURL ERROR 6 - Couldn't resolve host 'mirrors.easynews.com'Trying other mirror.http://mirrors.rit.edu/centos/6.5/extras/x86_64/repodata/repomd.xml: [Errno 14] PYCURL ERROR 6 - Couldn't resolve host 'mirrors.rit.edu'Trying other mirror.http://mirrors.sonic.net/centos/6.5/extras/x86_64/repodata/repomd.xml: [Errno 14] PYCURL ERROR 6 - Couldn't resolve host 'mirrors.sonic.net'Trying other mirror.http://mirrors.syringanetworks.net/centos/6.5/extras/x86_64/repodata/repomd.xml: [Errno 14] PYCURL ERROR 6 - Couldn't resolve host 'mirrors.syringanetworks.net'Trying other mirror.http://centos.aol.com/6.5/updates/x86_64/repodata/repomd.xml: [Errno 14] PYCURL ERROR 6 - Couldn't resolve host 'centos.aol.com'Trying other mirror.http://centos.eecs.wsu.edu/6.5/updates/x86_64/repodata/repomd.xml: [Errno 14] PYCURL ERROR 6 - Couldn't resolve host 'centos.eecs.wsu.edu'Trying other mirror.http://centos.host-engine.com/6.5/updates/x86_64/repodata/repomd.xml: [Errno 14] PYCURL ERROR 6 - Couldn't resolve host 'centos.host-engine.com'Trying other mirror.http://mirror.cisp.com/CentOS/6.5/updates/x86_64/repodata/repomd.xml: [Errno 14] PYCURL ERROR 6 - Couldn't resolve host 'mirror.cisp.com'Trying other mirror.http://mirror.linux.duke.edu/pub/centos/6.5/updates/x86_64/repodata/repomd.xml: [Errno 14] PYCURL ERROR 6 - Couldn't resolve host 'mirror.linux.duke.edu'Trying other mirror.http://mirror.tocici.com/centos/6.5/updates/x86_64/repodata/repomd.xml: [Errno 14] PYCURL ERROR 6 - Couldn't resolve host 'mirror.tocici.com'Trying other mirror.http://mirrors.liquidweb.com/CentOS/6.5/updates/x86_64/repodata/repomd.xml: [Errno 14] PYCURL ERROR 6 - Couldn't resolve host 'mirrors.liquidweb.com'Trying other mirror.http://mirrors.seas.harvard.edu/centos/6.5/updates/x86_64/repodata/repomd.xml: [Errno 14] PYCURL ERROR 6 - Couldn't resolve host 'mirrors.seas.harvard.edu'Trying other mirror.ftp://ftp.wallawalla.edu/pub/mirrors/centos/6.5/updates/x86_64/repodata/repomd.xml: [Errno 14] PYCURL ERROR 6 - Couldn't resolve host 'ftp.wallawalla.edu'Trying other mirror.ftp://mirror.nandomedia.com/pub/CentOS/6.5/updates/x86_64/repodata/repomd.xml: [Errno 14] PYCURL ERROR 6 - Couldn't resolve host 'mirror.nandomedia.com'Trying other mirror.Setting up Install ProcessResolving Dependencies--> Running transaction check---> Package perl-XML-Simple.noarch 0:2.18-6.el6 will be installed--> Finished Dependency ResolutionDependencies Resolved====================================================================================================================================================================================================================================== Package                                                       Arch                                                 Version                                                  Repository                                          Size======================================================================================================================================================================================================================================Installing: perl-XML-Simple                                               noarch                                               2.18-6.el6                                               base                                                72 kTransaction Summary======================================================================================================================================================================================================================================Install       1 Package(s)Total download size: 72 kInstalled size: 155 kIs this ok [y/N]: yDownloading Packages:http://centos.mirror.ndchost.com/6.5/os/x86_64/Packages/perl-XML-Simple-2.18-6.el6.noarch.rpm: [Errno 14] PYCURL ERROR 6 - Couldn't resolve host 'centos.mirror.ndchost.com'Trying other mirror.http://mirror.cs.vt.edu/pub/CentOS/6.5/os/x86_64/Packages/perl-XML-Simple-2.18-6.el6.noarch.rpm: [Errno 14] PYCURL ERROR 6 - Couldn't resolve host 'mirror.cs.vt.edu'Trying other mirror.http://mirror.pac-12.org/6.5/os/x86_64/Packages/perl-XML-Simple-2.18-6.el6.noarch.rpm: [Errno 14] PYCURL ERROR 6 - Couldn't resolve host 'mirror.pac-12.org'Trying other mirror.http://mirror.rackspace.com/CentOS/6.5/os/x86_64/Packages/perl-XML-Simple-2.18-6.el6.noarch.rpm: [Errno 14] PYCURL ERROR 6 - Couldn't resolve host 'mirror.rackspace.com'Trying other mirror.http://mirror.raystedman.net/centos/6.5/os/x86_64/Packages/perl-XML-Simple-2.18-6.el6.noarch.rpm: [Errno 14] PYCURL ERROR 6 - Couldn't resolve host 'mirror.raystedman.net'Trying other mirror.http://mirror.solarvps.com/centos/6.5/os/x86_64/Packages/perl-XML-Simple-2.18-6.el6.noarch.rpm: [Errno 14] PYCURL ERROR 6 - Couldn't resolve host 'mirror.solarvps.com'Trying other mirror.http://mirror.team-cymru.org/CentOS/6.5/os/x86_64/Packages/perl-XML-Simple-2.18-6.el6.noarch.rpm: [Errno 14] PYCURL ERROR 6 - Couldn't resolve host 'mirror.team-cymru.org'Trying other mirror.http://mirrors.easynews.com//linux/centos/6.5/os/x86_64/Packages/perl-XML-Simple-2.18-6.el6.noarch.rpm: [Errno 14] PYCURL ERROR 6 - Couldn't resolve host 'mirrors.easynews.com'Trying other mirror.http://mirrors.usc.edu/pub/linux/distributions/centos/6.5/os/x86_64/Packages/perl-XML-Simple-2.18-6.el6.noarch.rpm: [Errno 14] PYCURL ERROR 6 - Couldn't resolve host 'mirrors.usc.edu'Trying other mirror.ftp://mirror.nandomedia.com/pub/CentOS/6.5/os/x86_64/Packages/perl-XML-Simple-2.18-6.el6.noarch.rpm: [Errno 14] PYCURL ERROR 6 - Couldn't resolve host 'mirror.nandomedia.com'Trying other mirror.Error Downloading Packages:  perl-XML-Simple-2.18-6.el6.noarch: failure: Packages/perl-XML-Simple-2.18-6.el6.noarch.rpm from base: [Errno 256] No more mirrors to try.This is the iptables output when the firewall is on. But when using yum I had done service iptables stopChain INPUT (policy ACCEPT 0 packets, 0 bytes) pkts bytes target     prot opt in     out     source               destination             0     0 ACCEPT     udp  --  virbr0 *       0.0.0.0/0            0.0.0.0/0           udp dpt:53     0     0 ACCEPT     tcp  --  virbr0 *       0.0.0.0/0            0.0.0.0/0           tcp dpt:53     0     0 ACCEPT     udp  --  virbr0 *       0.0.0.0/0            0.0.0.0/0           udp dpt:67     0     0 ACCEPT     tcp  --  virbr0 *       0.0.0.0/0            0.0.0.0/0           tcp dpt:67     8   560 ACCEPT     all  --  *      *       128.46.76.110        0.0.0.0/0               0     0 ACCEPT     all  --  *      *       128.0.0.0/8          0.0.0.0/0               0     0 ACCEPT     all  --  *      *       127.0.0.0/8          127.0.0.0/8             5   480 ACCEPT     all  --  *      *       0.0.0.0/0            0.0.0.0/0           state RELATED,ESTABLISHED     7   420 REJECT     all  --  *      *       0.0.0.0/0            0.0.0.0/0           reject-with icmp-host-prohibited Chain FORWARD (policy ACCEPT 0 packets, 0 bytes) pkts bytes target     prot opt in     out     source               destination             0     0 ACCEPT     all  --  *      virbr0  0.0.0.0/0            192.168.122.0/24    state RELATED,ESTABLISHED     0     0 ACCEPT     all  --  virbr0 *       192.168.122.0/24     0.0.0.0/0               0     0 ACCEPT     all  --  virbr0 virbr0  0.0.0.0/0            0.0.0.0/0               0     0 REJECT     all  --  *      virbr0  0.0.0.0/0            0.0.0.0/0           reject-with icmp-port-unreachable     0     0 REJECT     all  --  virbr0 *       0.0.0.0/0            0.0.0.0/0           reject-with icmp-port-unreachable     0     0 REJECT     all  --  *      *       0.0.0.0/0            0.0.0.0/0           reject-with icmp-host-prohibited Chain OUTPUT (policy ACCEPT 18 packets, 1788 bytes) pkts bytes target     prot opt in     out     source               destinationWhen the firewall was off it was:Chain INPUT (policy ACCEPT 0 packets, 0 bytes) pkts bytes target     prot opt in     out     source               destination         Chain FORWARD (policy ACCEPT 0 packets, 0 bytes) pkts bytes target     prot opt in     out     source               destination         Chain OUTPUT (policy ACCEPT 0 packets, 0 bytes) pkts bytes target     prot opt in     out     source               destination /etc/resolv.conf# Generated by NetworkManagersearch ecn.xxx.purdue.edu# No nameservers found; try putting DNS servers into your# ifcfg files in /etc/sysconfig/network-scripts like so:## DNS1=xxx.xxx.xxx.xxx# DNS2=xxx.xxx.xxx.xxx# DOMAIN=lab.foo.com bar.foo.com
Network firewall on CentOS, host cannot be resolved?
networking;centos;iptables;firewall