Search Results

Search found 33162 results on 1327 pages for 'static ip address'.

facebook twitter digg google delicious technorati stumbleupon myspace wordpress linkedin gmail igoogle windows live tumblr viadeo yahoo buzz yahoo mail yahoo bookmarks favorites email print

Page 107/1327 | < Previous Page | 103 104 105 106 107 108 109 110 111 112 113 114  | Next Page >

  • Linux as a gateway (no NAT)

    - by Hugo
    I'm trying to configure a linux server as a gateway/router, but I can't get it to work, and all information I've managed to find is NAT-related. I have a public IP block for the gateway and devices behind it, so I want the gateway to simply route packets to the internet - again: no NATing! I've managed to get the gateway to access the internet successfully (that was just a matter of configuring the IP and GW), and the computers behind it can communicate with it. [EDIT: more info] This is actually an IPv6 block (2800:40:403::0/48) (but I've found that most utilities and instructions can be easily adapted from IPv4 to IPv6 with little hastle). The server has too ports: wan: 2800:40:403::1/48 lan: 2800:40:403::3/48 One of the computers behind it is connected to it via a switch; 2800:40:403::7/48 The wan interface on the server can ping6 www.google.com without issues. The lan interface on the server and the client can mutually ping each other without issues (as well as SSH, etc). I've tried setting the server as a default gateway for the client, with no luck: client # route -A inet6 add default gw 2800:40:403::3 dev eth1 server # cat /proc/sys/net/ipv6/conf/all/forwarding 1 I don't want any filtering/firewalling/etc, just plain routing. Thanks.

    Read the article

  • DNS redirecting to Apache

    - by leo
    I have CentOS installed on LVM, that is on Debian. There are BIND and Apache on CentOS. I need to access sites from browser on Debian with names like: 1.domain, 2.domain, etc. So I set up Apache and I can access these sites, but using /etc/hosts/ on Debian. And now I'm trying to configure bind. named.conf: zone "domain" IN { type master; file "/var/named/domain.zone"; allow-update { none; }; }; 192.168.100.1 is DNS' ip; 192.168.100.139 is Apache ip; domain.zone: $TTL 86400 @ IN SOA domain. root.domain. ( 100 1H 1M 1W 1D ) @ IN NS ns1.domain. @ IN A 192.168.100.139 ns1 IN A 192.168.100.1 WWW IN A 192.168.100.139 1 IN A 192.168.100.139 2 IN A 192.168.100.139 www.1 IN A 192.168.100.139 www.2 IN A 192.168.100.139 Also, is it necessary to configure 100.168.192.in-addr.arpa? Please, explain me where I'm wrong.

    Read the article

  • Understanding CNAME in displaydns

    - by dublintech
    On windows, I do ipconfig /displaydns One record is: na4.salesforce.com ---------------------------------------- Record Name . . . . . : na4.salesforce.com Record Type . . . . . : 5 Time To Live . . . . : 8 Data Length . . . . . : 8 Section . . . . . . . : Answer CNAME Record . . . . : na4-was.salesforce.com I see not IP for it. How does windows resolve the IP for this then? Note: there is no other entry for na-4-was.salesforce.com. Thanks,

    Read the article

  • MySQL - display rows of names and addresses grouped by name, where name occures more than once

    - by Stoob
    I have two tables, "name" and "address". I would like to list the last_name and joined address.street_address of all last_name in table "name" that occur more than once in table "name". The two tables are joined on the column "name_id". The desired output would appear like so: 213 | smith | 123 bluebird | 14 | smith | 456 first ave | 718 | smith | 12 san antonia st. | 244 | jones | 78 third ave # 45 | 98 | jones | 18177 toronto place | Note that if the last_name "abernathy" appears only once in table "name", then "abernathy" should not be included in the result. This is what I came up with so far: SELECT name.name_id, name.last_name, address.street_address, count(*) FROM `name` JOIN `address` ON name.name_id = address.name_id GROUP BY `last_name` HAVING count(*) > 1 However, this produces only one row per last name. I'd like all the last names listed. I know I am missing something simple. Any help is appreciated, thanks!

    Read the article

  • Nginx + Wordpress Multisite 3.4.2 + subdirectories + static pages and permalinks

    - by UrkoM
    I am trying to setup Wordpress Multisite, using subdirectories, with Nginx, php5-fpm, APC, and Batcache. As many other people, I am getting stuck in the rewrite rules for permalinks. I have followed these two guides, which seem to be as official as you can get: http://evansolomon.me/notes/faster-wordpress-multisite-nginx-batcache/ http://codex.wordpress.org/Nginx#WordPress_Multisite_Subdirectory_rules It is partially working: http://blog.ssis.edu.vn works. http://blog.ssis.edu.vn/umasse/ works. But other permalinks, like these two to a post or to a static page, don't work: http://blog.ssis.edu.vn/umasse/2008/12/12/hello-world-2/ http://blog.ssis.edu.vn/umasse/sample-page/ They either take you to a 404 error, or to some other blog! Here is my configuration: server { listen 80 default_server; server_name blog.ssis.edu.vn; root /var/www; access_log /var/log/nginx/blog-access.log; error_log /var/log/nginx/blog-error.log; location / { index index.php; try_files $uri $uri/ /index.php?$args; } # Add trailing slash to */wp-admin requests. rewrite /wp-admin$ $scheme://$host$uri/ permanent; # Add trailing slash to */username requests rewrite ^/[_0-9a-zA-Z-]+$ $scheme://$host$uri/ permanent; # Directives to send expires headers and turn off 404 error logging. location ~* \.(js|css|png|jpg|jpeg|gif|ico)$ { expires 24h; log_not_found off; } # this prevents hidden files (beginning with a period) from being served location ~ /\. { access_log off; log_not_found off; deny all; } # Pass uploaded files to wp-includes/ms-files.php. rewrite /files/$ /index.php last; if ($uri !~ wp-content/plugins) { rewrite /files/(.+)$ /wp-includes/ms-files.php?file=$1 last; } # Rewrite multisite '.../wp-.*' and '.../*.php'. if (!-e $request_filename) { rewrite ^/[_0-9a-zA-Z-]+(/wp-.*) $1 last; rewrite ^/[_0-9a-zA-Z-]+.*(/wp-admin/.*\.php)$ $1 last; rewrite ^/[_0-9a-zA-Z-]+(/.*\.php)$ $1 last; } location ~ \.php$ { # Forbid PHP on upload dirs if ($uri ~ "uploads") { return 403; } client_max_body_size 25M; try_files $uri =404; fastcgi_pass unix:/var/run/php5-fpm.sock; fastcgi_index index.php; fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name; include /etc/nginx/fastcgi_params; } } Any ideas are welcome! Have I done something wrong? I have disabled Batcache to see if it makes any difference, but still no go.

    Read the article

  • Set source address to use tun device does not work (Debian Squeeze)

    - by A. Donda
    there have been similar questions on StackExchange but none of the answers helped me, so I'll try a question of my own. I have a VPN connection via OpenVPN. By default, all traffic is redirected through the tunnel using OpenVPN's "two more specific routes" trick, but I disabled that. My routing table is like this: 198.144.156.141 192.168.2.1 255.255.255.255 UGH 0 0 0 eth0 10.30.92.5 0.0.0.0 255.255.255.255 UH 0 0 0 tun1 10.30.92.1 10.30.92.5 255.255.255.255 UGH 0 0 0 tun1 192.168.2.0 0.0.0.0 255.255.255.0 U 0 0 0 eth0 0.0.0.0 10.30.92.5 0.0.0.0 UG 0 0 0 tun1 0.0.0.0 192.168.2.1 0.0.0.0 UG 0 0 0 eth0 And the interface configuration is like this: # ifconfig eth0 Link encap:Ethernet HWaddr XX-XX- inet addr:192.168.2.100 Bcast:192.168.2.255 Mask:255.255.255.0 inet6 addr: fe80::211:9ff:fe8d:acbd/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:394869 errors:0 dropped:0 overruns:0 frame:0 TX packets:293489 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:388519578 (370.5 MiB) TX bytes:148817487 (141.9 MiB) Interrupt:20 Base address:0x6f00 tun1 Link encap:UNSPEC HWaddr 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00 inet addr:10.30.92.6 P-t-P:10.30.92.5 Mask:255.255.255.255 UP POINTOPOINT RUNNING NOARP MULTICAST MTU:1500 Metric:1 RX packets:64 errors:0 dropped:0 overruns:0 frame:0 TX packets:67 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:100 RX bytes:9885 (9.6 KiB) TX bytes:4380 (4.2 KiB) plus the lo device. The routing table has two default routes, one via eth0 through my local network router (DSL modem) at 192.168.2.1, and another via tun1 through the VPN's gateway. With this configuration, if I connect to a site, the route chosen is the direct one (because it has less hops?): # traceroute 8.8.8.8 -n traceroute to 8.8.8.8 (8.8.8.8), 30 hops max, 60 byte packets 1 192.168.2.1 0.427 ms 0.491 ms 0.610 ms 2 213.191.89.13 17.981 ms 20.137 ms 22.141 ms 3 62.109.108.48 23.681 ms 25.009 ms 26.401 ms ... This is fine, because my goal is to send only traffic from specific applications through the tunnel (esp. transmission, using its -i / bind-address-ipv4 option). To test whether this can work at all, I check it first with traceroute's -s option: # traceroute 8.8.8.8 -n -s 10.30.92.6 traceroute to 8.8.8.8 (8.8.8.8), 30 hops max, 60 byte packets 1 * * * 2 * * * 3 * * * ... This I take to mean that connection using the tunnel's local address as source is not possible. What is possible (though only as root) is to specify the source interface: # traceroute 8.8.8.8 -n -i tun1 traceroute to 8.8.8.8 (8.8.8.8), 30 hops max, 60 byte packets 1 10.30.92.1 129.337 ms 297.758 ms 297.725 ms 2 * * * 3 198.144.152.17 297.653 ms 297.652 ms 297.650 ms ... So apparently the tun1 interface is working and it is possible to send packets through it. But selecting the source interface is not implemented in my actual target application (transmission), so I would like to get source address selection to work. What am I doing wrong?

    Read the article

  • Linux, some packets are not being NAT

    - by user70932
    Hi, I'm trying to NAT HTTP traffic, I'm new to this and facing some issues. What i'm trying to do is NAT client HTTP requests to a webserver. CLIENT - NAT BOX - WEBSERVER When the client open the IP of the NAT BOX, the request should be pass to the web server. But I'm getting "HTTP request sent, awaiting response..." and then wait serveral minutes before the request is done. Looking at the tcpdump output, it looks like the first Syn packet on (10:48:54) is being NAT but not the second, third, fourth... ACK or PSH packets, and wait until (10:52:04) it starts NAT again on the ACK packet. The iptables command I'm using is: iptables -t nat -A PREROUTING -p tcp -i eth0 --dport 80 \ -j DNAT --to-destination WEBSERVER I'm wondering what could have caused this behavior? Thanks alot. 10:48:54.907861 IP (tos 0x0, ttl 49, id 16395, offset 0, flags [DF], proto: TCP (6), length: 48) CLIENT.61736 > NATBOX.http: S, cksum 0x6019 (correct), 1589600740:1589600740(0) win 5840 <mss 1460,nop,wscale 8> 10:48:54.907874 IP (tos 0x0, ttl 48, id 16395, offset 0, flags [DF], proto: TCP (6), length: 48) CLIENT.61736 > WEBSERVER.http: S, cksum 0xb5d7 (correct), 1589600740:1589600740(0) win 5840 <mss 1460,nop,wscale 8> 10:48:55.102696 IP (tos 0x0, ttl 49, id 16397, offset 0, flags [DF], proto: TCP (6), length: 40) CLIENT.61736 > NATBOX.http: ., cksum 0x2727 (correct), ack 2950613896 win 23 10:48:55.102963 IP (tos 0x0, ttl 49, id 16399, offset 0, flags [DF], proto: TCP (6), length: 160) CLIENT.61736 > NATBOX.http: P 0:120(120) ack 1 win 23 10:48:58.103078 IP (tos 0x0, ttl 49, id 16401, offset 0, flags [DF], proto: TCP (6), length: 160) CLIENT.61736 > NATBOX.http: P 0:120(120) ack 1 win 23 10:48:58.366344 IP (tos 0x0, ttl 49, id 16403, offset 0, flags [DF], proto: TCP (6), length: 40) CLIENT.61736 > NATBOX.http: ., cksum 0x26af (correct), ack 1 win 23 10:49:04.103204 IP (tos 0x0, ttl 49, id 16405, offset 0, flags [DF], proto: TCP (6), length: 160) CLIENT.61736 > NATBOX.http: P 0:120(120) ack 1 win 23 10:49:04.363943 IP (tos 0x0, ttl 49, id 16407, offset 0, flags [DF], proto: TCP (6), length: 40) CLIENT.61736 > NATBOX.http: ., cksum 0x26af (correct), ack 1 win 23 10:49:16.101583 IP (tos 0x0, ttl 49, id 16409, offset 0, flags [DF], proto: TCP (6), length: 160) CLIENT.61736 > NATBOX.http: P 0:120(120) ack 1 win 23 10:49:16.363475 IP (tos 0x0, ttl 49, id 16411, offset 0, flags [DF], proto: TCP (6), length: 40) CLIENT.61736 > NATBOX.http: ., cksum 0x26af (correct), ack 1 win 23 10:49:40.100796 IP (tos 0x0, ttl 49, id 16413, offset 0, flags [DF], proto: TCP (6), length: 160) CLIENT.61736 > NATBOX.http: P 0:120(120) ack 1 win 23 10:49:40.563898 IP (tos 0x0, ttl 49, id 16415, offset 0, flags [DF], proto: TCP (6), length: 40) CLIENT.61736 > NATBOX.http: ., cksum 0x26af (correct), ack 1 win 23 10:50:28.099396 IP (tos 0x0, ttl 49, id 16417, offset 0, flags [DF], proto: TCP (6), length: 160) CLIENT.61736 > NATBOX.http: P 0:120(120) ack 1 win 23 10:50:28.761678 IP (tos 0x0, ttl 49, id 16419, offset 0, flags [DF], proto: TCP (6), length: 40) CLIENT.61736 > NATBOX.http: ., cksum 0x26af (correct), ack 1 win 23 10:52:04.093668 IP (tos 0x0, ttl 49, id 16421, offset 0, flags [DF], proto: TCP (6), length: 160) CLIENT.61736 > NATBOX.http: P 0:120(120) ack 1 win 23 10:52:04.093678 IP (tos 0x0, ttl 48, id 16421, offset 0, flags [DF], proto: TCP (6), length: 160) CLIENT.61736 > WEBSERVER.http: P 1589600741:1589600861(120) ack 2950613896 win 23 10:52:04.291021 IP (tos 0x0, ttl 49, id 16423, offset 0, flags [DF], proto: TCP (6), length: 40) CLIENT.61736 > NATBOX.http: ., cksum 0x25d3 (correct), ack 217 win 27 10:52:04.291028 IP (tos 0x0, ttl 48, id 16423, offset 0, flags [DF], proto: TCP (6), length: 40) CLIENT.61736 > WEBSERVER.http: ., cksum 0x7b91 (correct), ack 217 win 27 10:52:04.300708 IP (tos 0x0, ttl 49, id 16425, offset 0, flags [DF], proto: TCP (6), length: 40) CLIENT.61736 > NATBOX.http: ., cksum 0x253c (correct), ack 368 win 27 10:52:04.300714 IP (tos 0x0, ttl 48, id 16425, offset 0, flags [DF], proto: TCP (6), length: 40) CLIENT.61736 > WEBSERVER.http: ., cksum 0x7afa (correct), ack 368 win 27 10:52:04.301417 IP (tos 0x0, ttl 49, id 16427, offset 0, flags [DF], proto: TCP (6), length: 40) CLIENT.61736 > NATBOX.http: F, cksum 0x253b (correct), 120:120(0) ack 368 win 27 10:52:04.301438 IP (tos 0x0, ttl 48, id 16427, offset 0, flags [DF], proto: TCP (6), length: 40) CLIENT.61736 > WEBSERVER.http: F, cksum 0x7af9 (correct), 120:120(0) ack 368 win 27 10:52:04.498875 IP (tos 0x0, ttl 49, id 16429, offset 0, flags [DF], proto: TCP (6), length: 40) CLIENT.61736 > NATBOX.http: ., cksum 0x253a (correct), ack 369 win 27 10:52:04.498881 IP (tos 0x0, ttl 48, id 16429, offset 0, flags [DF], proto: TCP (6), length: 40) CLIENT.61736 > WEBSERVER.http: ., cksum 0x7af8 (correct), ack 369 win 27

    Read the article

  • Exposing the AnyConnect HTTPS service to outside network

    - by Maciej Swic
    We have a Cisco ASA 5505 with firmware ASA9.0(1) and ASDM 7.0(2). It is configured with a public ip address, and when trying to reach it from the outside by HTTPS for AnyConnect VPN, we get the following log output: 6 Nov 12 2012 07:01:40 <client-ip> 51000 <asa-ip> 443 Built inbound TCP connection 2889 for outside:<client-ip>/51000 (<client-ip>/51000) to identity:<asa-ip>/443 (<asa-ip>/443) 6 Nov 12 2012 07:01:40 <client-ip> 50999 <asa-ip> 443 Built inbound TCP connection 2890 for outside:<client-ip>/50999 (<client-ip>/50999) to identity:<asa-ip>/443 (<asa-ip>/443) 6 Nov 12 2012 07:01:40 <client-ip> 51000 <asa-ip> 443 Teardown TCP connection 2889 for outside:<client-ip>/51000 to identity:<asa-ip>/443 duration 0:00:00 bytes 0 No valid adjacency 6 Nov 12 2012 07:01:40 <client-ip> 50999 <asa-ip> 443 Teardown TCP connection 2890 for outside:<client-ip>/50999 to identity:<asa-ip>/443 duration 0:00:00 bytes 0 No valid adjacency We finished the startup wizard and the anyconnect vpn wizard and here is the resulting configuration: Cryptochecksum: 12262d68 23b0d136 bb55644a 9c08f86b : Saved : Written by enable_15 at 07:08:30.519 UTC Mon Nov 12 2012 ! ASA Version 9.0(1) ! hostname vpn domain-name office.<redacted>.com enable password <redacted> encrypted passwd <redacted> encrypted names ip local pool vpn-pool 192.168.67.2-192.168.67.253 mask 255.255.255.0 ! interface Ethernet0/0 switchport access vlan 2 ! interface Ethernet0/1 ! interface Ethernet0/2 ! interface Ethernet0/3 ! interface Ethernet0/4 ! interface Ethernet0/5 ! interface Ethernet0/6 ! interface Ethernet0/7 ! interface Vlan1 nameif inside security-level 100 ip address 192.168.68.250 255.255.255.0 ! interface Vlan2 nameif outside security-level 0 ip address <redacted> 255.255.255.248 ! ftp mode passive dns server-group DefaultDNS domain-name office.<redacted>.com object network obj_any subnet 0.0.0.0 0.0.0.0 pager lines 24 logging enable logging asdm informational mtu outside 1500 mtu inside 1500 icmp unreachable rate-limit 1 burst-size 1 no asdm history enable arp timeout 14400 no arp permit-nonconnected ! object network obj_any nat (inside,outside) dynamic interface timeout xlate 3:00:00 timeout pat-xlate 0:00:30 timeout conn 1:00:00 half-closed 0:10:00 udp 0:02:00 icmp 0:00:02 timeout sunrpc 0:10:00 h323 0:05:00 h225 1:00:00 mgcp 0:05:00 mgcp-pat 0:05:00 timeout sip 0:30:00 sip_media 0:02:00 sip-invite 0:03:00 sip-disconnect 0:02:00 timeout sip-provisional-media 0:02:00 uauth 0:05:00 absolute timeout tcp-proxy-reassembly 0:01:00 timeout floating-conn 0:00:00 dynamic-access-policy-record DfltAccessPolicy user-identity default-domain LOCAL http server enable http 192.168.68.0 255.255.255.0 inside no snmp-server location no snmp-server contact snmp-server enable traps snmp authentication linkup linkdown coldstart warmstart crypto ipsec ikev2 ipsec-proposal DES protocol esp encryption des protocol esp integrity sha-1 md5 crypto ipsec ikev2 ipsec-proposal 3DES protocol esp encryption 3des protocol esp integrity sha-1 md5 crypto ipsec ikev2 ipsec-proposal AES protocol esp encryption aes protocol esp integrity sha-1 md5 crypto ipsec ikev2 ipsec-proposal AES192 protocol esp encryption aes-192 protocol esp integrity sha-1 md5 crypto ipsec ikev2 ipsec-proposal AES256 protocol esp encryption aes-256 protocol esp integrity sha-1 md5 crypto ipsec security-association pmtu-aging infinite crypto dynamic-map SYSTEM_DEFAULT_CRYPTO_MAP 65535 set ikev2 ipsec-proposal AES256 AES192 AES 3DES DES crypto map outside_map 65535 ipsec-isakmp dynamic SYSTEM_DEFAULT_CRYPTO_MAP crypto map outside_map interface outside crypto map inside_map 65535 ipsec-isakmp dynamic SYSTEM_DEFAULT_CRYPTO_MAP crypto map inside_map interface inside crypto ca trustpoint _SmartCallHome_ServerCA crl configure crypto ca trustpoint ASDM_TrustPoint0 enrollment self subject-name CN=vpn proxy-ldc-issuer crl configure crypto ca trustpool policy crypto ca certificate chain _SmartCallHome_ServerCA certificate ca 6ecc7aa5a7032009b8cebcf4e952d491 <redacted> quit crypto ca certificate chain ASDM_TrustPoint0 certificate f678a050 <redacted> quit crypto ikev2 policy 1 encryption aes-256 integrity sha group 5 2 prf sha lifetime seconds 86400 crypto ikev2 policy 10 encryption aes-192 integrity sha group 5 2 prf sha lifetime seconds 86400 crypto ikev2 policy 20 encryption aes integrity sha group 5 2 prf sha lifetime seconds 86400 crypto ikev2 policy 30 encryption 3des integrity sha group 5 2 prf sha lifetime seconds 86400 crypto ikev2 policy 40 encryption des integrity sha group 5 2 prf sha lifetime seconds 86400 crypto ikev2 enable outside client-services port 443 crypto ikev2 remote-access trustpoint ASDM_TrustPoint0 telnet timeout 5 ssh 192.168.68.0 255.255.255.0 inside ssh timeout 5 console timeout 0 vpn-addr-assign local reuse-delay 60 dhcpd auto_config outside ! dhcpd address 192.168.68.254-192.168.68.254 inside ! threat-detection basic-threat threat-detection statistics access-list no threat-detection statistics tcp-intercept ssl trust-point ASDM_TrustPoint0 inside ssl trust-point ASDM_TrustPoint0 outside webvpn enable outside enable inside anyconnect image disk0:/anyconnect-win-3.1.01065-k9.pkg 1 anyconnect image disk0:/anyconnect-linux-3.1.01065-k9.pkg 2 anyconnect image disk0:/anyconnect-macosx-i386-3.1.01065-k9.pkg 3 anyconnect profiles GM-AnyConnect_client_profile disk0:/GM-AnyConnect_client_profile.xml anyconnect enable tunnel-group-list enable group-policy GroupPolicy_GM-AnyConnect internal group-policy GroupPolicy_GM-AnyConnect attributes wins-server none dns-server value 192.168.68.254 vpn-tunnel-protocol ikev2 ssl-client default-domain value office.<redacted>.com webvpn anyconnect profiles value GM-AnyConnect_client_profile type user username <redacted> password <redacted> encrypted tunnel-group GM-AnyConnect type remote-access tunnel-group GM-AnyConnect general-attributes address-pool vpn-pool default-group-policy GroupPolicy_GM-AnyConnect tunnel-group GM-AnyConnect webvpn-attributes group-alias GM-AnyConnect enable ! class-map inspection_default match default-inspection-traffic ! ! policy-map type inspect dns preset_dns_map parameters message-length maximum client auto message-length maximum 512 policy-map global_policy class inspection_default inspect dns preset_dns_map inspect ftp inspect h323 h225 inspect h323 ras inspect rsh inspect rtsp inspect esmtp inspect sqlnet inspect skinny inspect sunrpc inspect xdmcp inspect sip inspect netbios inspect tftp inspect ip-options ! service-policy global_policy global prompt hostname context call-home reporting anonymous Cryptochecksum:12262d6823b0d136bb55644a9c08f86b : end Clearly we are missing something, but the question is, what?

    Read the article

  • What can Haskell's type system do that Java's can't and vice versa?

    - by Matt Fenwick
    I was talking to a friend about the differences between the type systems of Haskell and Java. He asked me what Haskell's could do that Java's couldn't, and I realized that I didn't know. After thinking for a while, I came up with a very short list of minor differences. Not being heavy into type theory, I'm left wondering whether they're formally equivalent. To try and keep this from becoming a subjective question, I'm asking: what are the major, non-syntactical differences between their type systems? I realize some things are easier/harder in one than in the other, and I'm not interested in talking about those. And to make it more specific, let's ignore Haskell type extensions since there's so many out there that do all kinds of crazy/cool stuff.

    Read the article

  • What can Haskell's type system do that Java's can't?

    - by Matt Fenwick
    I was talking to a friend about the differences between the type systems of Haskell and Java. He asked me what Haskell's could do that Java's couldn't, and I realized that I didn't know. After thinking for a while, I came up with a very short list of minor differences. Not being heavy into type theory, I'm left wondering whether they're formally equivalent. To try and keep this from becoming a subjective question, I'm asking: what are the major, non-syntactical differences between their type systems? I realize some things are easier/harder in one than in the other, and I'm not interested in talking about those. And to make it more specific, let's ignore Haskell type extensions since there's so many out there that do all kinds of crazy/cool stuff.

    Read the article

  • Type checking and recursive types (Writing the Y combinator in Haskell/Ocaml)

    - by beta
    When explaining the Y combinator in the context of Haskell, it's usually noted that the straight-forward implementation won't type-check in Haskell because of its recursive type. For example, from Rosettacode [1]: The obvious definition of the Y combinator in Haskell canot be used because it contains an infinite recursive type (a = a -> b). Defining a data type (Mu) allows this recursion to be broken. newtype Mu a = Roll { unroll :: Mu a -> a } fix :: (a -> a) -> a fix = \f -> (\x -> f (unroll x x)) $ Roll (\x -> f (unroll x x)) And indeed, the “obvious” definition does not type check: ?> let fix f g = (\x -> \a -> f (x x) a) (\x -> \a -> f (x x) a) g <interactive>:10:33: Occurs check: cannot construct the infinite type: t2 = t2 -> t0 -> t1 Expected type: t2 -> t0 -> t1 Actual type: (t2 -> t0 -> t1) -> t0 -> t1 In the first argument of `x', namely `x' In the first argument of `f', namely `(x x)' In the expression: f (x x) a <interactive>:10:57: Occurs check: cannot construct the infinite type: t2 = t2 -> t0 -> t1 In the first argument of `x', namely `x' In the first argument of `f', namely `(x x)' In the expression: f (x x) a (0.01 secs, 1033328 bytes) The same limitation exists in Ocaml: utop # let fix f g = (fun x a -> f (x x) a) (fun x a -> f (x x) a) g;; Error: This expression has type 'a -> 'b but an expression was expected of type 'a The type variable 'a occurs inside 'a -> 'b However, in Ocaml, one can allow recursive types by passing in the -rectypes switch: -rectypes Allow arbitrary recursive types during type-checking. By default, only recursive types where the recursion goes through an object type are supported. By using -rectypes, everything works: utop # let fix f g = (fun x a -> f (x x) a) (fun x a -> f (x x) a) g;; val fix : (('a -> 'b) -> 'a -> 'b) -> 'a -> 'b = <fun> utop # let fact_improver partial n = if n = 0 then 1 else n*partial (n-1);; val fact_improver : (int -> int) -> int -> int = <fun> utop # (fix fact_improver) 5;; - : int = 120 Being curious about type systems and type inference, this raises some questions I'm still not able to answer. First, how does the type checker come up with the type t2 = t2 -> t0 -> t1? Having come up with that type, I guess the problem is that the type (t2) refers to itself on the right side? Second, and perhaps most interesting, what is the reason for the Haskell/Ocaml type systems to disallow this? I guess there is a good reason since Ocaml also will not allow it by default even if it can deal with recursive types if given the -rectypes switch. If these are really big topics, I'd appreciate pointers to relevant literature. [1] http://rosettacode.org/wiki/Y_combinator#Haskell

    Read the article

  • How to solve 404 for static files with Django and Nginx?

    - by Lucio
    I setup a Trusty VM with Django + Nginx (other stuffs too). The server is working, I get the "Welcome to Django" page. But when I enter to servername/admin it loads the HTML page but fails to load the static content. And the admin page have this links to static content: <link rel="stylesheet" type="text/css" href="/static/admin/css/base.css" /> <link rel="stylesheet" type="text/css" href="/static/admin/css/login.css" /> Both of the CSS files give me 404, as the Nginx log shows: 192.168.56.1 - - [05/Jun/2014:12:04:09 -0300] "GET /admin HTTP/1.1" 301 5 "-" "Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:29.0) Gecko/20100101 Firefox/29.0" 192.168.56.1 - - [05/Jun/2014:12:04:09 -0300] "GET /admin/ HTTP/1.1" 200 833 "-" "Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:29.0) Gecko/20100101 Firefox/29.0" 192.168.56.1 - - [05/Jun/2014:12:04:10 -0300] "GET /static/admin/css/base.css HTTP/1.1" 404 142 "http://ubuntu-server/admin/" "Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:29.0) Gecko/20100101 Firefox/29.0" 192.168.56.1 - - [05/Jun/2014:12:04:10 -0300] "GET /static/admin/css/login.css HTTP/1.1" 404 142 "http://ubuntu-server/admin/" "Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:29.0) Gecko/20100101 Firefox/29.0" I think that the error is on my nginx.conf file, but do not know how to solve it.

    Read the article

  • Dynamic vs Statically typed languages for websites

    - by Bradford
    Wanted to hear what others thought about this statement: I’ll contrast that with building a website. When rendering web pages, often you have very many components interacting on a web page. You have buttons over here and little widgets over there and there are dozens of them on a webpage, as well as possibly dozens or hundreds of web pages on your website that are all dynamic. With a system with a really large surface area like that, using a statically typed language is actually quite inflexible. I would find it painful probably to program in Scala and render a web page with it, when I want to interactively push around buttons and what-not. If the whole system has to be coherent, like the whole system has to type check just to be able to move a button around, I think that can be really inflexible. Source: http://www.infoq.com/interviews/kallen-scala-twitter

    Read the article

  • Types of semantic bugs, logic errors [closed]

    - by C-Otto
    I am a PhD student and currently focus on automatically finding instances of new types of bugs in (Java) programs that cannot be found by existing tools like FindBugs. The existing tool currently is used to prove/disprove termination of (Java) programs. I have some ideas (see below), but I could need more input from you (experienced programmers, potential users of my tool). What kind of bugs do you wish to find? What types of bugs exist and might be suitable for my analysis? One strength of the approach I use is detailled information about the heap. So in contrast to FindBugs, I can work with knowledge of the form "variable x and variable y are disjoint on the heap" or "variable z is not cyclic". It is also possible to see if a method might have side effects (and if so, which variables may/may not be affected by it). Example 1: Vacuous call: Graph graphOne = createGraph(); Graph graphTwo = createGraph(); Node source = graphTwo.getRootNode(); for (Node n : graphOne.getNodes()) { if (areConnected(source, n)) { graphTwo.addNode(n); } } Imagine createGraph() creates a fresh graph, so that graphOne and graphTwo are disjoint on the heap. Then, because source is taken from graphTwo instead of graphOne, the call to areConnected always returns false. In this situation I could find out that the call areConnected is useless (because it does not have any side effect and the return value always is false) which helps finding the real bug (taking source from the wrong graph). For this the information that x and y are disjoint (because graphOne and graphTwo are disjoint) is crucial. This bug is related to calling x.equals(y) where x and y are objects of different classes. In this scenario, most implementations of equals() always return false, which most likely is not the intended result. FindBugs already finds this bug (hardcoded to equals(), semantics of implementation is not checked). Example 2: Useless code: someCode(); while (something()) { yetMoreSomething(); } moreCode(); In the case that the loop (so the code in something() and yetMoreSomething()) does not modify anything visible outside the loop, it does not make sense to run this code - the program has the same behaviour as someCode(); moreCode() (i.e., without the loop). To find this out, one needs detailled information about the side effects of the (possibly useless) code. If I can prove that the code does not have any side effect that can be observed afterwards (in the example: in moreCode() or later), then the code indeed is useless. Of course, here Input/Output of any form must be seen as a side effect, so that a System.out.println(...) is not considered useless. Example 3: Ignored return value: Instead of x = foo(); and making use of x, the method is called without storing the result: foo();. If the method does not have any side effect, its invocation is useless and can be dropped. Most likely, the bug here is that the returned value should have been used. Here, too, detailled information about side effects are needed. Can you think of similar types of bugs that might be detected (only) with detailled information about the heap, side effects, semantics of called methods, ...? Did you encounter bugs related to the ones shown below in "real life"? By the way, the tool is AProVE and Java related publications can be found on my homepage. Thanks a lot, Carsten

    Read the article

  • Seeking a free Lint for C which programmers will *want* to use

    - by Mawg
    When I try to persuade others to Lint their code I always get excuses - too difficult to set up, too difficult to understand, false positives, etc (most of which translates to too lazy, too stupid or too afraid of new things). Is there any way that I can make Linting easier? We code in C using Netbeans. Can I incorporate Splint into Netbeans? I did find a Splint GUI which was quite good, but there was no way to lint a directory tree. Any ideas? Thanks in advance

    Read the article

  • Are the only types of data "sources" static and dynamic?

    - by blunders
    Thinking that there might be others, but not sure -- but before getting into that, let me explain what I mean by static and dynamic data sources. Static (or datastore) - Meaning that the data's state is non-changing, and if was changed, that would be a new state, and the old data would be considered stateless; meaning it no longer is known to exist, or not exist. Another way of possibly looking at a static data source might be that if read and written back without modification, the checksum for before and after should be exactly the same regardless of the duration of time between the reading and rewriting of the data. Examples: Photos, Files, Database Record, Dynamic (or datastream) - Meaning that the data's state is known to be in flux, and never expected to be the same per input. Example: Live video/audio feed, Stock Market feed, First let me say, the above is a very loose mapping of the concepts, and I'd welcome any feedback. Next, onto the core of the question, that being are these the only two types of data sources. My guess, is that yes, they are -- but that there are hybrid versions of the two. That being, streaming data that has a fixed state. For example, the data being streamed has a checksum given and each unique checksum is known to be a single instance of static data. On the flip side, static data could be chained via say a version control system; when played back, each version might be viewed as a segment of a stream; thing is, the very fact that it can be played back makes the data source static. Another type might be that the data source is being organically discovered, and it's simply unknown what the state is. Questions, feedback, requests -- just comment, thanks!!

    Read the article

  • Can I use a 302 redirect to serve up static content from a url with escaped_fragment?

    - by Starfs
    We would like to serve up seo-friendly ajax-driven content. We are following this documentation. Has anyone ever tried to write a 302 redirect into the htaccess file, that takes the '?_escaped_fragment=' string and send that to a static page? For example /snapshot/yourfilename/ How will Google react to this? I've gone through the documentation and it's not very clear. The below quote is from Google's documentation this is what I find. I'm not sure if they are saying that you can redirect the _escaped_fragment_ url to a different static page, or if this is to redirect the hashtag URL to static content? Thoughts? From Google's site: Question: Can I use redirects to point the crawler at my static content? Redirects are okay to use, as long as they eventually get you to a page that's equivalent to what the user would see on the #! version of the page. This may be more convenient for some webmasters than serving up the content directly. If you choose this approach, please keep the following in mind: Compared to serving the content directly, using redirects will result in extra traffic because the crawler has to follow redirects to get the content. This will result in a somewhat higher number of fetches/second in crawl activity. Note that if you use a permanent (301) redirect, the url shown in our search results will typically be the target of the redirect, whereas if a temporary (302) redirect is used, we'll typically show the #! url in search results. Depending on how your site is set up, showing #! may produce a better user experience, because the user will be taken straight into the AJAX experience from the Google search results page. Clicking on a static page will take them to the static content, and they may experience avoidable extra page load time if the site later wants to switch them to the AJAX experience.

    Read the article

  • Dynamically vs Statically typed languages studies

    - by Winston Ewert
    Do there exist studies done on the effectiveness of statically vs dynamically typed languages? In particular: Measurements of programmer productivity Defect Rate Also including the effects of whether or not unit testing is employed. I've seen lots of discussion of the merits of either side but I'm wondering whether anyone has done a study on it. Edit Sadly, only one of the papers shown is actually a study and it does nothing but conclude that the language matters. This leads me to ponder: what if I proposed doing such a study with volunteers from this site?

    Read the article

  • Nginx Cache-Control

    - by optixx
    Iam serving my static content with ngnix. location /static { alias /opt/static/blog/; access_log off; etags on; etag_hash on; etag_hash_method md5; expires 1d; add_header Pragma "public"; add_header Cache-Control "public, must-revalidate, proxy-revalidate"; } The resulting header looks like this: Cache-Control:public, must-revalidate, proxy-revalidate Cache-Control:max-age=86400 Connection:close Content-Encoding:gzip Content-Type:application/x-javascript; charset=utf-8 Date:Tue, 11 Sep 2012 08:39:05 GMT Etag:e2266fb151337fc1996218fafcf3bcee Expires:Wed, 12 Sep 2012 08:39:05 GMT Last-Modified:Tue, 11 Sep 2012 06:22:41 GMT Pragma:public Server:nginx/1.2.2 Transfer-Encoding:chunked Vary:Accept-Encoding Why is nginx sending 2 Cache-Control entries, could this be a problem for the clients?

    Read the article

  • Using a nat rule to translate 80/443 traffic to web server, but internal users cannot access it using external ip/domain name

    - by Josh
    I am using Cisco ASDM for ASA I have my internal network called soa. My outside interface is called outside. Let's say my outside IP given to me by my ISP isp is y.y.y.y I have a web server inside my network with a static ip of x.x.x.110. I have configured 2 static nat rules (one for http the other for https). Source is x.x.x.110. Interface is outside, service (http or https). Maybe I am doing this wrong, but when I run the packet tracer, I choose outside interface and for the source IP I used 8.8.8.8 and the destination ip is my outside IP address, y.y.y.y When I run that, it shows the packet traversing successfully, using 9 steps. For my other test, I switch to the soa interface, input an ip on that network, and leave the destination the same. This test comes up with 2 steps and then fails on my access list. When I see the rule that fails, it is my catch all which is source: any desitnation: any, service: ip action: deny. What rule do I need to make to allow my soa network access to go out and come back in by my external IP addess (using a domain name attached to that ip in my dns, of course)?

    Read the article

  • Can I use a 302 redirect to serve up static content from an URL with escaped_fragment?

    - by Starfs
    We would like to serve up SEO-friendly Ajax-driven content. We are following this documentation. Has anyone ever tried to write a 302 redirect into the .htaccess file, that takes the ?_escaped_fragment= string and send that to a static page?, for example /snapshot/yourfilename/. How will Google react to this? I've gone through the documentation and it's not very clear. The below quote is from Google's documentation this is what I find. I'm not sure if they are saying that you can redirect the _escaped_fragment_ URL to a different static page, or if this is to redirect the hashtag URL to static content? Thoughts? From Google's site: Question: Can I use redirects to point the crawler at my static content? Redirects are okay to use, as long as they eventually get you to a page that's equivalent to what the user would see on the #! version of the page. This may be more convenient for some webmasters than serving up the content directly. If you choose this approach, please keep the following in mind: Compared to serving the content directly, using redirects will result in extra traffic because the crawler has to follow redirects to get the content. This will result in a somewhat higher number of fetches/second in crawl activity. Note that if you use a permanent (301) redirect, the url shown in our search results will typically be the target of the redirect, whereas if a temporary (302) redirect is used, we'll typically show the #! url in search results. Depending on how your site is set up, showing #! may produce a better user experience, because the user will be taken straight into the AJAX experience from the Google search results page. Clicking on a static page will take them to the static content, and they may experience avoidable extra page load time if the site later wants to switch them to the AJAX experience.

    Read the article

  • helper functions as static functions or procedural functions?

    - by fayer
    i wonder if one should create a helper function in a class as a static function or just have it declared as a procedural function? i tend to think that a static helper function is the right way to go cause then i can see what kind of helper function it is eg. Database::connect(), File::create(). what is best practice?

    Read the article

  • cannot declare instance members in a static class in C#

    - by acadia
    Hello, I have a Public Static Class and I am trying to access appsettings from my app.config file in C# and I get the above error public static class employee { NameValueCollection appSetting = ConfigurationManager.AppSettings; } How do I get this to work? PS: I pasted just a few lines of code. thanks

    Read the article

  • Calling a static method on a generic type parameter

    - by Remi Despres-Smyth
    I was hoping to do something like this, but it appears to be illegal in C#: public Collection MethodThatFetchesSomething<T>() where T : SomeBaseClass { return T.StaticMethodOnSomeBaseClassThatReturnsCollection(); } I get a compile-time error: "'T' is a 'type parameter', which is not valid in the given context." Given a generic type parameter, how can I call a static method on the generic class? The static method has to be available, given the constraint.

    Read the article

facebook twitter digg google delicious technorati stumbleupon myspace wordpress linkedin gmail igoogle windows live tumblr viadeo yahoo buzz yahoo mail yahoo bookmarks favorites email print

< Previous Page | 103 104 105 106 107 108 109 110 111 112 113 114  | Next Page >