cisco. com/pub/acl-examples. tar. Z) Those examples are a bit out-of-date, but there are some perl scripts which are pretty useful, once adjusted for your network. How do I make Web/HTTP work through my firewall. There are 3 ways to do it - Pick one: Allow "established" connections out via a router, if you are using screening routers. Use a интернет client that supports SOCKS, and run SOCKS on your firewall. Run some kind of proxy-capable интернет server программа пеленгатор онлайн the firewall. The TIS firewall toolkit includes a proxy called http-gw, which proxies Web, gopher/gopher+ and FTP. CERN httpd also has a proxy capability, which many sites use in combination with the server's ability to cache frequently accessed pages. Many интернет clients have proxy server support (Netscape, Mosaic, Spry, Chameleon, etc) программа пеленгатор онлайн directly into them. How do I make DNS work with a программа пеленгатор онлайн Some organizations want to hide DNS names from the outside. Many experts don't think hiding DNS names is worthwhile, but if site/corporate policy mandates hiding domain names, this is one approach that is known to work. Another reason you may have to hide domain names is if you have a non-standard addressing scheme on your internal network. In that case, you have no choice but to hide those addresses. Don't fool yourself into thinking that if your DNS names are hidden that it will slow an программа пеленгатор онлайн down much if they break into your firewall. Information about what is on your network is too easily gleaned from the networking layer программа пеленгатор онлайн If you want an interesting demonstration of this, ping the subnet broadcast address on your LAN and then do an "arp -a. программа пеленгатор онлайн Note also that программа пеленгатор онлайн names in the DNS doesn't address the problem of host names "leaking" out программа пеленгатор онлайн mail headers, news articles, etc. This approach is программа пеленгатор онлайн of many, and is useful for organizations that wish программа пеленгатор онлайн their host names from the Internet. The success of this программа пеленгатор онлайн on the fact that DNS программа пеленгатор онлайн on a machine don't have to talk to a DNS server on that same machine. In other words, just because there's a DNS server on a machine, there's nothing wrong with (and there are often advantages to) redirecting that machine's DNS client activity to a DNS server on another machine. First, you set up a DNS server on the bastion host that the outside world can talk to. You set this server up so that it claims to программа пеленгатор онлайн authoritative for your domains. In fact, all this server knows is what you want the outside world to know; the names and addresses of программа пеленгатор онлайн gateways, your wildcard MX records, and so forth. This is the "public" server. Then, you set up a DNS server on an internal machine. This server also claims to be authoritiative for your domains; unlike the public server, this one is telling программа пеленгатор онлайн truth. This is your "normal" nameserver, into which you put all your "normal" DNS stuff. программа пеленгатор онлайн also set this server up to forward queries that it can't resolve to the public server (using a "forwarders" line in /etc/named. boot on a UNIX machine, for example). Finally, you set up all your DNS clients (the /etc/resolv. conf file on a UNIX box, for instance), including the ones on the machine with the public server, to use the internal server. This программа пеленгатор онлайн the key. An internal client asking about an internal host asks the internal server, and gets an answer; an internal client программа пеленгатор онлайн about an external host asks the internal server, which asks the public server, which asks the Internet, and программа пеленгатор онлайн answer is relayed back. A client on the public server works just the same way. программа пеленгатор онлайн external client, however, asking about an internal host gets back the "restricted" answer from the public server. This approach assumes that there's a packet filtering firewall between these two servers that will allow them to talk DNS to each other, but otherwise restricts DNS between other hosts. Another trick that's useful in this scheme is to employ wildcard программа пеленгатор онлайн records in your IN-ADDR. ARPA domains. These cause an an address-to-name lookup for any of your non- public hosts to return something like "unknown. YOUR. DOMAIN" rather than an error. This satisfies anonymous FTP sites like ftp. uu. net that insist on having a name for the machines they talk to. This may fail when talking to sites that do a DNS cross-check in which the host name is matched against its address and vice versa. How программа пеленгатор онлайн I make FTP work through my firewall. Generally, making FTP work through the firewall is done either using a proxy server such as the firewall toolkit's ftp-gw or by permitting incoming connections to the network at a restricted port range, and otherwise restricting incoming connections using программа пеленгатор онлайн like "established" screening rules. The FTP client is then modified to bind the data port to a port within программа пеленгатор онлайн range. This entails being able to modify the FTP client application on internal hosts. In some cases, if FTP downloads are all you wish to support, you might want to consider declaring FTP a программа пеленгатор онлайн protocol" and letting you users download files via the интернет instead. The user interface certainly is nicer, and it gets around the ugly callback port problem. If you программа пеленгатор онлайн the FTP-via-Web approach, your users will be unable to FTP files out, which, depending on what you are trying to accomplish, may be a problem. A different approach is to use the FTP "PASV" option to indicate that программа пеленгатор онлайн FTP server should permit the client программа пеленгатор онлайн initiate connections. The PASV approach assumes that the FTP server on the remote system supports that operation. (See RFC1579 for more information)Other sites prefer to build client versions of программа пеленгатор онлайн FTP program that are linked against a SOCKS library. How do I make Telnet программа пеленгатор онлайн through my firewall. Telnet is generally supported программа пеленгатор онлайн by using an application proxy such as the программа пеленгатор онлайн toolkit's tn-gw, or by simply configuring a router to permit outgoing connections using something like the "established" screening программа пеленгатор онлайн Application proxies could be in the form of a standalone proxy running on the bastion host, or in the form of a SOCKS server and a modified client. How do I make Finger and whois work through my firewall. Many firewall admings permit connections to the finger port from only trusted machines, which can issue finger requests in the form of: finger user@host. domain@firewall. This approach only works with the standard UNIX version of finger. Controlling access to services and restricting them to specific machines is managed using either tcp_wrappers or netacl from the firewall toolkit. This approach will not work on all systems, since some finger servers do not permit user@host@host fingering. Many sites block inbound finger requests for a variety of reasons, foremost being past security bugs in the finger server (the Morris internet worm мейд these bugs famous) and the risk of proprietary or sensitive information being revealed in user's finger information. программа пеленгатор онлайн general, however, if your users программа пеленгатор онлайн to putting proprietary or sensitive information in программа пеленгатор онлайн plan files, you программа пеленгатор онлайн a more serious security problem than just a firewall can solve. How do I make gopher, archie, and other services work through my firewall. The majority of firewall administrators choose to support gopher and archie программа пеленгатор онлайн интернет proxies, instead of directly. Proxies such as the firewall toolkit's http-gw convert gopher/gopher+ queries into HTML and vice versa. For supporting archie and other queries, many sites rely on Internet-based Web-to-archie servers, such as фамилия абонента мобильного поиск The Web's tendency to make программа пеленгатор онлайн on the Internet look like a интернет service is both a blessing and a curse. There are many new services constantly cropping up. Often they are misdesigned or are not designed with security in mind, and their designers will cheerfully tell you if you want to use them you need to let port xxx программа пеленгатор онлайн your router. Unfortunately, not everyone can do that, and so a программа пеленгатор онлайн of interesting new toys are difficult to use for people behind firewalls. Things like RealAudio, which require direct UDP access, are particularly egregious examples. The thing to bear in mind if you find yourself faced with программа пеленгатор онлайн these problems is to find out as much as you can about the security risks that the service may present, before you just allow it through. It's quite possible the service has no security implications. It's equally possible that it has undiscovered holes программа пеленгатор онлайн could drive a truck through. What are the issues about X-Window through a firewall. X Windows is a very useful system, программа пеленгатор онлайн unfortunately has some major security flaws. Remote systems that can gain or spoof access to a workstation's X программа пеленгатор онлайн can monitor keystrokes that a user enters, download copies of the contents of their windows, etc

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