I manage a linux-based network, where some projects are currently under development. Our IT policy states that any email attachment shall be encrypted using GPG. Can I block other attachments using a firewall?
Note: Currently our mail server is not in campus. So I can only use a firewall for this security issue.
I was wondering how to block attachments to gmail. I am running squid 2.7 stab9 with dansguardian 2.10, users authenticated from LDAP. I have configured the POST restrictions in Dansguardian which does block all attachments to hotmail/yahoo etc etc but attachments to gmail continue to upload.
View 1 Replies View RelatedI have noticed interesting problem. I use two browsers - Firefox and Konqueror. Konqueror is configured to use tor, Firefox not. Using Gufw I block all incoming and outgoing traffic and it works while using Firefox, I mean that I can't view any www site and it is ok. But if I use Konqueror I can establish any conection. How to understand this? Should I have different firewall while using tor?
View 5 Replies View RelatedI launched my website. At the moment the site has an firewall (iptables) enabled with very simple rules. All incoming traffic is blocked, except for the ports http and ssh. Everything is working perfect, but I want also to be able to block certain kinds of attacks. There are some really good examples on the internet, but I don't now if they contain all kinds of attacks which are relevant to my situation. To be clear, I only server web content through port 80 and use ssh to remote login.
View 3 Replies View RelatedI have centos 5.3 installed with squid server. I want to block attachment in yahoo, google, etc.
View 1 Replies View RelatedDuring a recent install I made the leap to encryption,but /boot must remain unencrypted.Is there really any legitimate security risk to having an unencrypted /boot partition? I mean basically someone can just see what kernel you're running which they could see during boot anyways right? Oh I and keep all my financial documents in /boot/finances/ (haha ok not really, but I am serious about the first part).
View 5 Replies View RelatedI would like to know the blocking methode In a Firewall or a Router.whether i will be done by Protocol wise, ho? or it will done through Host wise, How ?
View 2 Replies View RelatedI'm at a complete loss on this one.MY version of Firefox 3.6.10 (Ubuntu 10.04 LTS) opens all email attachments with no problem. However, my sister's machine--same 3.6.10 and 10.04 LTS--does not. Instead, she gets the following message: "(PDF or JPEG) could not be opened because the associated helper application does not exist. Change the association in your preferences."I've checked all her preference settings against mine, and they match...but mine works and hers does not. (Also verified that "Document Viewer" and "Image Viewer" are installed properly...)
View 5 Replies View RelatedI'm about to start trying to write a script to backup / with just something like tar, or dd, split into 24mb files and email to myself.What could possibly go wrong? I'm amazed I couldn't find anything in my searches on this specifically.What I want is to go from a Gentoo rescue CD to a restored system as easily as possible.I tried rsync over gmailfs but that just froze. I can't really see that working too well anyway.
View 2 Replies View RelatedI have an interesting job at hand. A client has asked me to generate an email account for him that will block ALL file attachments unless specific email addresses are added to a white list. Cpanel doesn't seem to allow this because of Exim (from what the server techs tell me).So here I am, asking the wise. Please let me know what options there are. I don't mind installing a 3rd party email system on the server just for this client if it's possible and won't interfere with WHM/Cpanel.
View 1 Replies View RelatedI admit to being a starter having recently switched from XP. How do I deliver emails to the remaining XP users that that have attachments thay can read if they are using microsoft packages of various ages especially when they have less computer skills than even me. Should I load word through WINE and send an Word emulating document?
View 3 Replies View RelatedIs there a way of allowing only certain domain to send e-mails to certain specific e-mail address. I am using Sendmail, and I have an alias which translate to certain members of staff within my organization. I don't expect e-mails from outside our domain to be sent to this alias e-mail address.
View 1 Replies View RelatedI was having a discussion with someone who said that telnet, FTP, HTTP plain-text authentication in the local subnet is ok because it's a switched network. Also, that these protocols are not good over the net but in a local subnet they are just fine.
I know that someone can plug a hub in the network port and connect 2 (or more) PCs and see the packets. Also, heard about ettercap but haven't really delved into it. I know dsniff was written to prove the point that unencrypted protocols are bad. Would like to get opinion about unencrypted protocols over a switched networks.
I followed this howto in order to mount CIFS shares on demand. This works great, however, this guide suggests leaving my network passwords unencrypted on the disk. This is a very bad security practice, as the passwords can be easly retrieved by booting the computer using a different OS.
I was looking for a way to secure things up, so I came up with this solution: Instead of storing the passwords plain text on the disk, I store them in a tar file encrypted using GPG. When I boot my system, I open this file to a directory in /dev/shm, and order AutoFS to retrieve the passwords from there.
This does the trick, but I presume this solution is not that secure, since /dev/shm content can be written to the swap partition. Is there any other solution which is a better security practice? Maybe using some sort of keyring service?
how to unblock email with attachment .zip should be all attachment through to my email i have below message when people sent me email to my domain
Warning: This message has had one or more attachments removed
Warning: (the entire message).
Warning: Please read the "Apex-Attachment-Warning.txt" attachment(s) for more information.
This is a message from the MailScanner E-Mail Virus Protection Service The original e-mail message contained potentially dangerous content, which has been removed for your safety. The content is dangerous as it is often used to spread viruses or to gain personal or confidential information from you, such as passwords or credit card numbers.
Can we use iptables as firewall instead of Juniper firewall
View 2 Replies View RelatedHow I can refuse an outgoing connection on opensuse firewall by default outbound policy is permissive, and the p2p I explicitly deny an outgoing, according to protocol, remote port and local port.
But I can add rules as how to run opensuse firewall rules are permissive only for inbound traffic and so I can not specifically deny an outgoing connection.
Before using fwbuilder is very powerful and configurable but now I'm with suse for convenience but want to know if you can do what I want, if not I will have to use fwbuilder.
Link 1 = my network [url]
My network:
Subnet 1
Subnet 2
When someone creates a network loop (a cat 5 cable is plugged into two ports on a switch), the 2 subnet get flooded and become very slow.
How can I prevent subnet 1 from getting flood if someone create a loop on subnet 2.
- eth2 go offline automatically until the network loop is canceled.
I've been all around the net and can't find a "simple" answer how to block our LAN users from downloading torrents. Is it really that difficult?
Here's our setup:
1. The Server's Configs:
2. sudo gedit /etc/squid/squid.conf
3. sudo gedit /etc/rc.local (to start Firewall rules on bootup)
4. Server NOT a DHCP Server
5. No other iptables rules are configured, just the above ones.
Before in a 1 NIC setup, I blocked Workstations MAC addresses in the Router + Squid Proxy Server (Not Transparent), it worked, but some Online Java Apps didn't work and users can't send/receive email so I abandoned the method.
Now, I installed transparent Squid Proxy with 2 NIC cards, it works, but workstations can still download torrents! I know Squid doesn't block ports, right? So the answer must lie in Iptables Firewall? I basically use Squid just to deny access to Facebook, Friendster, or other "unproductive sites".
Quote:
How to block torrent downloading by using a Firewall? Or is there another "simple" way?
I've heard that it's better just to allow regular ports (80, 22, 465, etc...) then block all the rest, this way, you can prevent unnecessary ports.
I'm not an Iptables/Firewall expert so can you pls. explain it a bit more detailed if that's the case.
I'm also aware of just telling our users NOT to download torrents, but I just want to prohibit it entirely.
I know I will be the most "uncool" employee in our office.
I have a ubuntu computer set up as bridge between gateway and lan, with the lan connected to eth0 and gateway on eth1.
I'm trying to get it to basically block everything incoming except for the ports i specify, but also allow outgoing traffic. I've found, tried, modified som examples i found on the web, but still it wont block incoming traffic (ie, im still able to reach my webserver)
These are the rules, and i can't figure out why it wont block:
Code:
#!/bin/bash
iptables -F
iptables -X
iptables -I INPUT -i eth1 -j DROP
[Code].....
I want to set up Ubuntu Server as a firewall in which I want to direct my internet connection through where Ubuntu Server will block, filter, and monitor anything that come into either three of my computers using the same internet connection. Is this easy to do? sum up the steps that I will have to go through to establish this, and any relevant information, and where I might be able to find necessary information etc. I plan to use ubuntu-10.04.2-server-i386.
View 3 Replies View RelatedI already have Linux Enterprise 5 system installed with some server packages such as Webmin, Active Directory, Web Server which also act as Internet gateway. Now I want to add firewall functionality to block clients ip accessing internet.
View 14 Replies View RelatedI am still new to ubuntu and I use firestarter as my firewall tool and I was told that its just ufw in a gui. Well anyways I noticed a connection to 174.129.241.144 using https and python, I didn't have any scripts running and my browser was closed, I read the man files for ufw and it said to do something like deny from 174.129.0.0/12 and I want to block all incoming and outgoing connections to this IP range and I was wondering how to do that, I heard of iptables that it would be able to do this but I dont know anything about it. What I should learn so I can handle these kinds of situation in the future and how I can block this ip subnet or also what does the /8, /12, and /16 stand for?
View 7 Replies View Relatedtell me the command for iptable rule to add in Chain RH-Firewall-1 to block ftp port & the ftp server was configured in public ip address,i searched in google but i did'nt get the exact command for iptables rule in Chain RH-Firewall-1.
View 3 Replies View RelatedI don't know what to do, I know how to block and delete pretty much every other type of abuse. I run a server with 500+ shared hosting clients and reseller clients and it was just blocked because of email spam. I can keep on top of all other abuse (people trying to do dos attacks etc) but the one thing I can't get my head around is email spamming. how to stop people spamming emails from my server?
View 7 Replies View RelatedI run my own home server using OpenSuse 11.1, everything is setup using apache, php, etc etc, and it all works perfect, but now I need to use my own email server for the use of Dolphin social networking software, so that when someone registers, the email server sends out registration confirmation emails, so I set up postfix, yeah right!!!, even though I followed all instructions to set postfix as a closed relay, a test done at mxtoolbox site still said it was an open relay, but while I was trying to set up postfix, my access to the server slowed down, and my servers drive light was constantly active,,, so when I look at the mail queue, I saw 4000+ emails, all from japan, (hinen.net), so I promptly shut down postfix and use postsuper -d ALL in the command console to delete the queue, but no matter how I try, I couldn't configure postfix as a closed relay,,, so I uninstalled it and installed sendmail, and using webmin, I could use a spam list and block the domain, now, sendmail's test at mxtools show as a closed relay, I can't even send out a test email using smtp auth, but disabling auth, I can, but now my IP is blocked at spam cop, and spamhaus,,, gmail server say my IP is not authorized to send to their servers, but to use my ISP relay instead,,, but my ISP doesn't have a relay,,hence the need to run my own email server.
My home server uses double layer firewall, a hardware firewall between the internet and the server, and a software firewall on the server, and I only allow the ports I need, IE, 80 = http, 443 = https, 20/21 = ftp, 25 = smtp, 110 = pop3. and that's all, but any other internal access from my workstation to the server, using ssh, I only open the ports on the server firewall. If someone here has a great deal of knowledge on sendmail, and can set up a an M4 (linux.mc) config file for me, it would be much appreciated. What I would like my email server to do, is to only allow the sending of emails from inside it's own server system,, ie, when a php script sends an email to the server, then the email server would let it through, but anything else, outside the local network is ignored.
i am using centos 5.4, running squid for proxy, i want to block email sending and receiving of proxy users to secure my data. how is it possible that the proxy user can only brows websites but he can not receive or open and send or save as draft to mail box.
View 1 Replies View RelatedThe problem I have is so simple yet difficult for me to resolve. My Postfix MTA allow fake mails from me@example.com to me@example.com. How can I block them?
For example, if I do "telnet smtp.mail.yahoo.it 25", as I write the MAIL FROM command I get the alert "Authentication required". How can I achieve that?
can we block email address in a way that a user cannot login into multiple systems simultaneously, so that if a user logs in into a system (with ip address 192.168.1.22)and if he tries to login to into another system at the same time(with ip address 10.0.0.5) his previous system(i.e 192.168.1.22) has to logout automatically. Is there any predefined scripts for this.
View 2 Replies View RelatedI want allow a local domain (domain.com) to send email ONLY locally, and I don't allow domain.com to send email to remote email (externally) . How to configure exim to do this ?
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