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  • how to setup a ssh acount with no terminal but port forwarding?

    - by admalledd
    I am trying to set up a new user account I can give to friends so they can SSH into my forward computer, and only allow forwarding of certain ports. I do not want my friends to have a shell, or be able to change what ports to where they are allowed to forward. example session: joe(friend) connects using PuTTY (that I have pre-set, he isn't good with computers) to example.com(my Internet facing computer) forwarding ports 8080,1990,25565 to him(with what ever end ports he wants, preferably they stay the same numbers) example ssh command to do similar (but he can still change the ports on my computer!) ssh -N [email protected] -p443 -L8080:192.168.1.2:8080 -L1990:127.0.0.1:1990 -L25565:127.0.0.1:25565 then, same story with other friend smith(same ports, same user even) except he is using linux, so cant use putty. is it possible to also leave default SSH functinality for all other users but this one? I found this when I was searching google, but alas, I did not quite understand what was being suggested, and I don't think they covered restricting port forwarding

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  • Can't connect to web-server on local host behind NAT

    - by eyeinthebrick
    I got Ubuntu as host. I'm running a web-server on http://192.168.199.8:80. It is accessible from the local network, but when I'm trying to reach it by external IP, I go to my router's web-page. I arranged port forwarding on router for port 80 to my local IP 192.168.199.8. Unfortunately web-server is still unavailable via external IP. I checked whether the port is open via http://www.canyouseeme.org/. As it showed that the port is unavailable, I changed port used to 3659 (not forget to rearrange port forwarding rule). Although http://www.canyouseeme.org/ shows that port 3659 is open, I still can't reach my web-server. Where can the problem be?

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  • Boost::Asio - Remove the "null"-character in the end of tcp packets.

    - by shump
    I'm trying to make a simple msn client mostly for fun but also for educational purposes. And I started to try some tcp package sending and receiving using Boost Asio as I want cross-platform support. I have managed to send a "VER"-command and receive it's response. However after I send the following "CVR"-command, Asio casts an "End of file"-error. After some further researching I found by packet sniffing that my tcp packets to the messenger server got an extra "null"-character (Ascii code: 00) at the end of the message. This means that my VER-command gets an extra character in the end which I don't think the messenger server like and therefore shuts down the connection when I try to read the CVR response. This is how my package looks when sniffing it, (it's Payload): (Hex:) 56 45 52 20 31 20 4d 53 4e 50 31 35 20 43 56 52 30 0a 0a 00 (Char:) VER 1 MSNP15 CVR 0... and this is how Adium(chat client for OS X)'s package looks: (Hex:) 56 45 52 20 31 20 4d 53 4e 50 31 35 20 43 56 52 30 0d 0a (Char:) VER 1 MSNP15 CVR 0.. So my question is if there is any way to remove the null-character in the end of each package, of if I've misunderstood something and used Asio in a wrong way. My write function (slightly edited) looks lite this: int sendVERMessage() { boost::system::error_code ignored_error; char sendBuf[] = "VER 1 MSNP15 CVR0\r\n"; boost::asio::write(socket, boost::asio::buffer(sendBuf), boost::asio::transfer_all(), ignored_error); if(ignored_error) { cout << "Failed to send to host!" << endl; return 1; } cout << "VER message sent!" << endl; return 0; } And here's the main documentation on the msn protocol I'm using. Hope I've been clear enough.

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  • make local only daemon listening on different interface (using iptables port forwarding)?

    - by UniIsland
    i have a daemon program which listens on 127.0.0.1:8000. i need to access it when i connect to my box with vpn. so i want it to listen on the ppp0 interface too. i've tried the "ssh -L" method. it works, but i don't think it's the right way to do that, having an extra ssh process running in the background. i tried the "netcat" method. it exits when the connection is closed. so not a valid way for "listening". i also tried several iptables rules. none of them worked. i'm not listing here all the rules i've used. iptables -A FORWARD -j ACCEPT iptables -t nat -A PREROUTING -i ppp+ -p tcp --dport 8000 -j DNAT --to-destination 127.0.0.1:8000 the above ruleset doesn't work. i have net.ipv4.ip_forward set to 1. anyone knows how to redirect traffic from ppp interface to lo? say, listen on "192.168.45.1:8000 (ppp0)" as well as "127.0.0.1:8000 (lo)" there's no need to alter the port. thanx

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  • iptables blocking ssh communication

    - by Michal Sapsa
    I'm using this script for iptables: #!/bin/sh echo "1" > /proc/sys/net/ipv4/ip_forward iptables -F iptables -X iptables -F -t nat iptables -X -t nat iptables -F -t filter iptables -X -t filter iptables -t filter -P FORWARD DROP iptables -t filter -A FORWARD -s 192.168.0.0/255.255.0.0 -d 0/0 -j ACCEPT iptables -t filter -A FORWARD -s 0/0 -d 192.168.0.0/255.255.0.0 -j ACCEPT iptables -t nat -A POSTROUTING -s 10.8.0.1/255.255.255.0 -j MASQUERADE iptables -A FORWARD -s 10.8.0.1/255.255.255.0 -j ACCEPT iptables -t nat -A POSTROUTING -s 192.168.0.0/24 -d 0/0 -j MASQUERADE iptables -I FORWARD -p tcp --tcp-flags SYN,RST SYN -j TCPMSS --clamp-mss-to-pmtu iptables -t nat -A PREROUTING -i eth1 -p udp --dport 16161 -j DNAT --to 192.168.0.251:16161 iptables -t nat -A PREROUTING -i eth1 -p udp --sport 16161 -j DNAT --to 192.168.0.251:16161 #openvpn iptables -I INPUT -p tcp --dport 1194 -j ACCEPT iptables -I INPUT -p udp --dport 1194 -j ACCEPT I end up with some iptables rules that should work but don't work - probably because of me. # Generated by iptables-save v1.4.12 on Mon May 26 13:15:43 2014 *raw :PREROUTING ACCEPT [1657523:1357257330] :OUTPUT ACCEPT [36804:34834370] -A PREROUTING -p icmp -j TRACE -A PREROUTING -p tcp -j TRACE -A OUTPUT -p icmp -j TRACE -A OUTPUT -p tcp -j TRACE COMMIT # Completed on Mon May 26 13:15:43 2014 # Generated by iptables-save v1.4.12 on Mon May 26 13:15:43 2014 *nat :PREROUTING ACCEPT [5033:345623] :INPUT ACCEPT [154:34662] :OUTPUT ACCEPT [6:1968] :POSTROUTING ACCEPT [2:120] -A PREROUTING -i eth0 -p tcp -m tcp --dport 16161 -j DNAT --to-destination 192.168.0.251:22 -A PREROUTING -i eth1 -p tcp -m tcp --dport 16161 -j DNAT --to-destination 192.168.0.251:22 -A POSTROUTING -s 10.8.0.0/24 -j MASQUERADE -A POSTROUTING -s 192.168.0.0/24 -j MASQUERADE COMMIT # Completed on Mon May 26 13:15:44 2014 # Generated by iptables-save v1.4.12 on Mon May 26 13:15:44 2014 *filter :INPUT ACCEPT [548:69692] :FORWARD DROP [8:384] :OUTPUT ACCEPT [2120:1097479] -A INPUT -p udp -m udp --dport 1194 -j ACCEPT -A INPUT -p tcp -m tcp --dport 1194 -j ACCEPT -A FORWARD -p tcp -m tcp --tcp-flags SYN,RST SYN -j TCPMSS --clamp-mss-to-pmtu -A FORWARD -s 192.168.0.0/16 -j ACCEPT -A FORWARD -d 192.168.0.0/16 -j ACCEPT -A FORWARD -s 10.8.0.0/24 -j ACCEPT -A FORWARD -i eth0 -o eth1 -p tcp -m tcp --dport 22 -j ACCEPT -A FORWARD -i eth1 -o eth0 -p tcp -m tcp --dport 22 -j ACCEPT COMMIT TRACE at PREROUTEING AND OUTPUT are only for debuging this thing. When I ssh at public ip with port 16161 I don't get any message, only TimeOut so it looks like I don't get communication back to remote server. ETH0 is the world, ETH1 is LAN Any IPTABLES Masters willing to give a hand ? iptables -vL Chain INPUT (policy ACCEPT 20548 packets, 3198K bytes) pkts bytes target prot opt in out source destination 38822 7014K ACCEPT udp -- any any anywhere anywhere udp dpt:openvpn 0 0 ACCEPT tcp -- any any anywhere anywhere tcp dpt:openvpn Chain FORWARD (policy DROP 1129 packets, 64390 bytes) pkts bytes target prot opt in out source destination 214K 11M TCPMSS tcp -- any any anywhere anywhere tcpflags: SYN,RST/SYN TCPMSS clamp to PMTU 4565K 1090M ACCEPT all -- any any 192.168.0.0/16 anywhere 5916K 7315M ACCEPT all -- any any anywhere 192.168.0.0/16 0 0 ACCEPT all -- any any 10.8.0.0/24 anywhere 0 0 ACCEPT tcp -- any any anywhere 192.168.0.251 tcp dpt:16161 Chain OUTPUT (policy ACCEPT 59462 packets, 19M bytes) pkts bytes target prot opt in out source destination

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  • Bind9 as a caching resolver fails with mismatch ID on localhost but not external IP

    - by argibbs
    I'm running Ubuntu 12.04 LTS on a machine on my private network. I have bind9 installed (v9.8.1-P1) via aptitude, so it appears to have put all the bits in the right places and the service starts automatically. I plan on adding some zones later, but first I'm just trying to get it working as a caching resolver. I installed bind, configured it, and starting using it. Initially I thought it was working ok, but then I found some sites weren't being resolved. I've pinned it down to being linked to the size of the result and bind failing-over to TCP mode. So: I'm trying to find out why bind is failing when I query for domain info and the result is 512 bytes (causing a truncation and retry on TCP). Specifically it fails with ID mismatches if I point dig at localhost, but works when I query the machine's own IP (192.168.0.2). This appears to be backwards to the problem that most people have when using bind (fails on external ip, works on localhost). If I do dig @localhost google.com (which has a response of <512 bytes) then it works; I get no warnings, and plenty of output. $ dig @localhost google.com ; <<>> DiG 9.8.1-P1 <<>> @localhost google.com [snip lots of output] ;; Query time: 39 msec ;; SERVER: 127.0.0.1#53(127.0.0.1) ;; WHEN: Thu Oct 17 23:08:34 2013 ;; MSG SIZE rcvd: 495 If I do dig @localhost play.google.com (which has a larger response) then I get back something like: $ dig @localhost play.google.com ;; Truncated, retrying in TCP mode. ;; ERROR: ID mismatch: expected ID 3696, got 27130 This seems to be standard, documented behaviour - when the UDP response is large (here 'large' == 512 bytes) it falls back to TCP. The ID mismatch is not expected though. If I do dig @192.168.0.2 play.google.com then I still get the warning about using TCP mode, but it otherwise works $ dig @192.168.0.2 play.google.com ;; Truncated, retrying in TCP mode. ; <<>> DiG 9.8.1-P1 <<>> @192.168.0.2 play.google.com [snip most of the output] ;; Query time: 5 msec ;; SERVER: 192.168.0.2#53(192.168.0.2) ;; WHEN: Thu Oct 17 23:05:55 2013 ;; MSG SIZE rcvd: 521 At the moment I've not set up any zones in my local instance, so it's just acting as a caching resolver. My options config is pretty much unchanged from standard, I've got the following set: options { directory "/var/cache/bind"; allow-query { 192.168/16; 127.0.0.1; }; forwarders { 8.8.8.8; 8.8.4.4; }; dnssec-validation auto; edns-udp-size 4096 ; allow-transfer { any; }; auth-nxdomain no; # conform to RFC1035 listen-on-v6 { any; }; }; And my /etc/resolv.conf is just nameserver 127.0.0.1 search .local The problem definitely seems linked to the failover to TCP mode: if I do dig +bufsize=4096 @localhost play.google.com then it works; no warning about failover to TCP, no ID mismatch, and a standard looking result. To be honest, if there was a way to force bind to use a much larger UDP buffer, that'd probably be good enough for me, but all I've been able to find mention of is max-udp-size 4096 and that doesn't change the behaviour in any way. I've also tried setting edns-udp-size 512 in case the problem is some weird EDNS issue with my router (which seems unlikely since the +bufsize=4096 flag works fine). I've also tried dig +trace @localhost play.google.com; this works. No truncation/TCP warning, and a full result. I've also tried changing the servers used in the forwarder (e.g. to OpenDNS), but that makes no difference. There's one last data point: if I repetitively do dig @localhost play.google.com I don't always get an ID mismatch, but sometimes a REFUSED error. I'm much more likely to get a REFUSED error if I dig the non-localhost IP (192.168.0.2) first: $ dig @localhost play.google.com ;; Truncated, retrying in TCP mode. ; <<>> DiG 9.8.1-P1 <<>> @localhost play.google.com ; (1 server found) ;; global options: +cmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: REFUSED, id: 35104 ;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 0 ;; QUESTION SECTION: ;play.google.com. IN A ;; Query time: 4 msec ;; SERVER: 127.0.0.1#53(127.0.0.1) ;; WHEN: Thu Oct 17 23:20:13 2013 ;; MSG SIZE rcvd: 33 Any insights or things to try would be much appreciated.

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  • Convert from port numbers to protocol names in wireshark

    - by Berkay
    i'm simply using tshark -r botnet.pcap -T fields -E separator=';' -e ip.src -e tcp.srcport -e ip.dst -e tcp.dstport '(tcp.flags.syn == 1 and tcp.flags.ack == 0)' to see the all initiated "legal TCP" connections. However, i need the destination port number conversion to "http" "netbios" etc. i'm not using -n option, but still i get: 128.3.45.128;62259;208.233.189.150;80 This is what i'm trying to get: 128.3.45.128;62259;208.233.189.150;http or 128.3.45.128;62259;208.233.189.150;80;http is better option for me. any idea from tshark users? or any other tool suggestions?

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  • Convert from port numbers to protocol names ?

    - by Berkay
    i'm simply using tshark -r botnet.pcap -T fields -E separator=';' -e ip.src -e tcp.srcport -e ip.dst -e tcp.dstport '(tcp.flags.syn == 1 and tcp.flags.ack == 0)' to see the all initiated "legal TCP" connections. However, i need the destination port number conversion to "http" "netbios" etc. i'm not using -n option, but still i get: 128.3.45.128;62259;208.233.189.150;80 This is what i'm trying to get: 128.3.45.128;62259;208.233.189.150;http or 128.3.45.128;62259;208.233.189.150;80;http is better option for me. any idea from tshark users? or any other tool suggestions?

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  • ipfw to redirect traffic from port 80 and 443 to 8080

    - by user1048138
    -A PREROUTING -s 10.0.10.0/24 -p tcp -m tcp --dport 80 -j REDIRECT --to-ports 8080 -A PREROUTING -s 10.0.10.0/24 -p tcp -m tcp --dport 443 -j REDIRECT --to-ports 8080 -A POSTROUTING -s 10.0.10.0/24 -o eth0 -j MASQUERADE The above code is what I have used on linux to forward my ports to 8080, how can I do the same on a mac? I have tried test_machine:~ root# ipfw show 00666 0 0 fwd 127.0.0.1,8080 tcp from any to me dst-port 80 and its not working! any suggestions?

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  • Reconstruct a file from a TCP stream

    - by Abhishek Chanda
    I have a client and a server and a third box which sees all packets from the server to the client (but not the other way around). Now when the client requests a file from the server (over HTTP), the third box sees the response. I am trying to reconstruct the file there. I am using libpcap to capture TCP datagrams and trying to reconstruct the file there. Here is what I did Listen for packets on an interface Group all packets which have the same ACK number Sort the group based on SEQ number Extract data from each packet and combine them and write to the disk The problem is, the file thus generated is not exactly the same as the original file. Does everything sound correct here? Some more details: I am using C++ The packet data is being stored as std::vector<char> I did change the byte order while reading the ack number and seq number from the packet using ntohl I am not sure if I need to change the byte order for the data as well. I tried to reverse the data from each packet before combining them, even that did not work. Is there something I am missing?

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  • proftpd, dynamic IP, and filezilla: port troubles

    - by Yami
    The basic setup: Two computers, one running proftpd, one attempting to connect via filezilla. Both linux (xubuntu on the server, kubuntu on the client). Both are at the moment behind a router on a residential (read: dynamic IP) connection; the client is a laptop I plan to take away from the home network, so I'll need this to work externally. I have my router set up to allow specific ports forwarded to each machine and, where possible, have plugged in those numbers into proftpd (via gadmin, double-checking the config file) and filezilla. Attempting to connect via active mode using the internal IP works: Status: Connecting to 192.168.1.139:8085... Status: Connection established, waiting for welcome message... Response: 220 Crossroads FTP Command: USER <redacted> Response: 331 Password required for <redacted> Command: PASS ******* Response: 230 Anonymous access granted, restrictions apply Command: OPTS UTF8 ON Response: 200 UTF8 set to on Status: Connected Status: Retrieving directory listing... Command: PWD Response: 257 "/" is the current directory Command: TYPE I Response: 200 Type set to I Command: PORT 192,168,1,52,153,140 Response: 200 PORT command successful Command: LIST Response: 150 Opening ASCII mode data connection for file list Response: 226 Transfer complete Status: Directory listing successful Attempting to connect via the domain name, however, leads to issues; in active mode, the PORT is the last command to be received according to the server's logs, and in passive mode, it's the PASV command. This leads me to believe I'm being redirected to a bad port? Active Sample: Status: Resolving address of <url> Status: Connecting to <ip:port> Status: Connection established, waiting for welcome message... Response: 220 Crossroads FTP Command: USER <redacted> Response: 331 Password required for <redacted> Command: PASS ******* Response: 230 Anonymous access granted, restrictions apply Command: OPTS UTF8 ON Response: 200 UTF8 set to on Status: Connected Status: Retrieving directory listing... Command: PWD Response: 257 "/" is the current directory Command: TYPE I Response: 200 Type set to I Command: PORT 174,111,127,27,153,139 Response: 200 PORT command successful Command: LIST Error: Connection timed out Error: Failed to retrieve directory listing Passive sample: Status: Resolving address of ftp.bonsaiwebdesigns.com Status: Connecting to 174.111.127.27:8085... Status: Connection established, waiting for welcome message... Response: 220 Crossroads FTP Command: USER yamikuronue Response: 331 Password required for yamikuronue Command: PASS ******* Response: 230 Anonymous access granted, restrictions apply Command: OPTS UTF8 ON Response: 200 UTF8 set to on Status: Connected Status: Retrieving directory listing... Command: PWD Response: 257 "/" is the current directory Command: TYPE I Response: 200 Type set to I Command: PASV Response: 227 Entering Passive Mode (64,95,64,197,101,88). Command: LIST Error: Connection timed out Error: Failed to retrieve directory listing In both cases, the log file ends at "PORT" or "PASV" - there's no record of ever receiving a "LIST" command. Just above that I can see the attempt to connect actively via the internal IP, which does indeed include a LIST command. My config file includes "PassivePorts 20001-26999", which are the port forwards I set up for the ftp server, and "Port 8085", which is also forwarded to the same machine. I also have a MasqueradeAddress set up to prevent it from reporting its internal IP, which was an earlier issue I had. I think what I'm asking is, is there another setting someplace I have to change to get this setup to work?

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  • What happens with TCP packets between 2 Socket.BeginReceive Call??

    - by Rodrigo
    Hi, i have a doubt about Socket Programming, i am developing a TCP packets Sniffer, i am using Socket.BeginAccept, Socket.BeginReceive to capture every packet, but when a packet is received i have to process something, it is a fast operation, but would take some milliseconds, and then call the BeginReceive again. My question is, what would happen if some packets are sent while i am processing, and havent called BeginReceive??...are lost?...are buffered internally?...is there a limit?... Thanks in advance.

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  • Why we need to read() before write() in TCP server program?

    - by Naga
    Hi, As per my understanding a simple TCP server will be coded as follows. socket() - bind() - listen() - accept() - read() - write() The clients will be written as follows. socket() - bind()(Optional) - connect() - write() - read() Please note the order difference in read() and write() calls between client and server program. Is it a requirement to always read() before write() in a server program and if, then why? Thanks, Naga

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