Most corporate networks are configured by undemocratic firewalls that protect internal users from themselves and hackers. By the way, for an experienced hacker even a high-quality and well-tuned firewall is not a barrier.
A firewall is generally a set of systems that provide an appropriate level of access control, achieved by controlling the traffic passing through a more or less flexible set of rules. Simply saying, the firewall passes only that part of the traffic that is explicitly allowed by the administrator and blocks everything else.
The market is dominated by two types of firewalls - packet filters, also called packet filter gateways, and application proxies. An example of the first type is the Firewall from Check Point, and the second is the Microsoft Proxy Server.
Packet filters are completely transparent to users and very productive, but not reliable enough. In fact, they represent a variety of routers that accept packets both from outside and inside the network, and decide how to proceed with them — pass further or destroy, notifying the sender if necessary that his packet is dead. Most firewalls of this type work at the IP level, and the completeness of support for the IP protocol and the quality of filtering is desired, so the attacker can easily deceive them. On home computers, such firewalls still make sense, but if there is even a bad router, it only increases the cost of the system without giving anything in return, since the same packet filtering rules can be set on the router as well!
Software proxies are regular ones that work on specific ports (for example, 25, 110, 80) and support interaction with a predetermined list of network services. Unlike filters that transmit IP packets. The proxy independently collects TCP packets, bites user data out of it, sticks a new header onto them, and reassembles the received packet on IP, performing address translation if necessary. If the firewall does not contain errors, it will not be possible to fool it at the network level; besides, it hides the structure of the internal network from the attacker - only a firewall remains outside. And in order to achieve the highest security, the administrator can organize additional authentication procedures on the firewall, “attacking” the enemy even at the far lines of defense. These were merits. As for the shortcomings, the software proxies limit users in the choice of applications. They run much slower than packet filters and greatly reduce performance (especially on fast channels).
Both types of firewalls usually include a more or less curtailed version of the Intruder Detection System (IDS) that analyzes the nature of network requests and identifies potentially dangerous actions — accessing non-existent ports (typical for scanning), TTL packets equal to one, (typical for tracing), etc. All this greatly complicates the attack, and the hacker has to act very cautiously, since any wrong step will immediately give it away with good luck. However, the intelligence of the integrated recognition systems is quite small, and most self-respecting administrators shift this task onto the shoulders of specialized packages, such as Real Secure from Internet Security System.
Depending on the network configuration, the firewall may be installed on a dedicated computer or it may share system resources with someone else. Personal firewalls, widespread in the Windows world, are overwhelmingly installed directly on the protected computer itself. If this packet filter is implemented without errors, then the security of the system does not suffer at all and it is as difficult to attack it as on a dedicated firewall. Local proxy software protects the computer only from some types of attacks (for example, blocking the sending of trojans via IE), leaving the system completely open. In UNIX-like-systems, the packet filter is initially present, and the standard package includes a large number of various proxy servers, so there is no need to purchase additional software. So definitely the answer is yes.
Yes, you can use private proxies to bypass the network firewall. If you have been blocked by a network firewall, you can use a proxy server to check if you can bypass it and gain access to the needed website. In most cases, the firewall blocks your IP address or a specific range of IP addresses.
You might be interested how to set it up? It is easy. Just a simple set-up procedure as always. In browser or OS - you should check our blog for a certain article.
Although some proxies can be tracked, it is important to note that they have different levels of anonymity — the highly anonymous proxies that our resource provides cannot be traced.
Unfortunately, no, you can not bypass a virus that blocks your access to the Internet through a proxy when your computer starts up normally. Some variants of malware have the ability to change the settings of your Internet browser by adding its own malicious proxy, changing the DNS settings of your computer, and even adding entries to your operating system's Hosts files. When this happens, you may face some problems with redirecting or that is completely blocking your Internet connection.