2015-02-25
Samsung TV decides the Internet is broken
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Currently our Samsung 'smart' TV is convinced the Internet is broken and refuses to start any of the applications. According to some network protocol sniffing the TV decides this purely based on a DNS query for www.samsung.com which takes an interesting CNAME tour. According to what I can find this hasn't changed when the smart TV stopped working so this must be something in the software in the TV itself.; <<>> DiG 9.4.2-P2.1 <<>> www.samsung.com a ;; global options: printcmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 39167 ;; flags: qr rd ra; QUERY: 1, ANSWER: 6, AUTHORITY: 0, ADDITIONAL: 0 ;; QUESTION SECTION: ;www.samsung.com. IN A ;; ANSWER SECTION: www.samsung.com. 253 IN CNAME www.samsung.com.edgekey.net. www.samsung.com.edgekey.net. 3171 IN CNAME www.samsung.com.akadns.net. www.samsung.com.akadns.net. 253 IN CNAME china-www.samsung.com.edgekey.net. china-www.samsung.com.edgekey.net. 2765 IN CNAME china-www.samsung.com.edgekey.net.globalredir.akadns.net. china-www.samsung.com.edgekey.net.globalredir.akadns.net. 853 IN CNAME e1722.g.akamaiedge.net. e1722.g.akamaiedge.net. 14 IN A 23.206.87.52 ;; Query time: 0 msec ;; SERVER: 2001:980:14ca:42::18#53(2001:980:14ca:42::18) ;; WHEN: Wed Feb 25 20:20:34 2015 ;; MSG SIZE rcvd: 244Online there are some similar messages: Smart TV mayhem for Sony and Samsung users after central servers go down, Internet-Ausfall bei Samsung Smart-TV Update:
According to some reports the fix is simple: Users fix Samsung Smart TV down time themselves – Two workarounds known which both hardcode an Akamai IP for www.samsung.com and skip the CNAME chain. Remember when DNS manuals told you CNAME chains were a bad idea? They still are, I guess. I implemented the fix locally with pdns-recursor and the export-etc-hosts option which allows me to serve an A record for www.samsung.com (the IP I get from the CNAME chain). And indeed, the smart TV applications work again. From a packet capture:User Datagram Protocol, Src Port: 59956 (59956), Dst Port: 53 (53) Source port: 59956 (59956) Destination port: 53 (53) Length: 41 Checksum: 0xcdd1 [correct] [Good Checksum: True] [Bad Checksum: False] Domain Name System (query) Transaction ID: 0xf31a Flags: 0x0100 (Standard query) 0... .... .... .... = Response: Message is a query .000 0... .... .... = Opcode: Standard query (0) .... ..0. .... .... = Truncated: Message is not truncated .... ...1 .... .... = Recursion desired: Do query recursively .... .... .0.. .... = Z: reserved (0) .... .... ...0 .... = Non-authenticated data OK: Non-authenticated data is unacceptable Questions: 1 Answer RRs: 0 Authority RRs: 0 Additional RRs: 0 Queries www.samsung.com: type A, class IN Name: www.samsung.com Type: A (Host address) Class: IN (0x0001) User Datagram Protocol, Src Port: 53 (53), Dst Port: 59956 (59956) Source port: 53 (53) Destination port: 59956 (59956) Length: 252 Checksum: 0x5185 [correct] [Good Checksum: True] [Bad Checksum: False] Domain Name System (response) [Request In: 5] [Time: 0.000155000 seconds] Transaction ID: 0xf31a Flags: 0x8180 (Standard query response, No error) 1... .... .... .... = Response: Message is a response .000 0... .... .... = Opcode: Standard query (0) .... .0.. .... .... = Authoritative: Server is not an authority for domain .... ..0. .... .... = Truncated: Message is not truncated .... ...1 .... .... = Recursion desired: Do query recursively .... .... 1... .... = Recursion available: Server can do recursive queries .... .... .0.. .... = Z: reserved (0) .... .... ..0. .... = Answer authenticated: Answer/authority portion was not authenticated by the server .... .... .... 0000 = Reply code: No error (0) Questions: 1 Answer RRs: 6 Authority RRs: 0 Additional RRs: 0 Queries www.samsung.com: type A, class IN Name: www.samsung.com Type: A (Host address) Class: IN (0x0001) Answers www.samsung.com: type CNAME, class IN, cname www.samsung.com.edgekey.net Name: www.samsung.com Type: CNAME (Canonical name for an alias) Class: IN (0x0001) Time to live: 1 minute, 59 seconds Data length: 29 Primary name: www.samsung.com.edgekey.net www.samsung.com.edgekey.net: type CNAME, class IN, cname www.samsung.com.akadns.net Name: www.samsung.com.edgekey.net Type: CNAME (Canonical name for an alias) Class: IN (0x0001) Time to live: 46 minutes, 17 seconds Data length: 25 Primary name: www.samsung.com.akadns.net www.samsung.com.akadns.net: type CNAME, class IN, cname china-www.samsung.com.edgekey.net Name: www.samsung.com.akadns.net Type: CNAME (Canonical name for an alias) Class: IN (0x0001) Time to live: 1 minute, 59 seconds Data length: 12 Primary name: china-www.samsung.com.edgekey.net china-www.samsung.com.edgekey.net: type CNAME, class IN, cname china-www.samsung.com.edgekey.net.globalredir.akadns.net Name: china-www.samsung.com.edgekey.net Type: CNAME (Canonical name for an alias) Class: IN (0x0001) Time to live: 49 minutes, 29 seconds Data length: 48 Primary name: china-www.samsung.com.edgekey.net.globalredir.akadns.net china-www.samsung.com.edgekey.net.globalredir.akadns.net: type CNAME, class IN, cname e1722.g.akamaiedge.net Name: china-www.samsung.com.edgekey.net.globalredir.akadns.net Type: CNAME (Canonical name for an alias) Class: IN (0x0001) Time to live: 1 minute, 17 seconds Data length: 21 Primary name: e1722.g.akamaiedge.net e1722.g.akamaiedge.net: type A, class IN, addr 23.206.87.52 Name: e1722.g.akamaiedge.net Type: A (Host address) Class: IN (0x0001) Time to live: 10 seconds Data length: 4 Addr: 23.206.87.52