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ssh host-keys not shown correctly #2105

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lmm-git opened this issue Aug 16, 2020 · 1 comment · Fixed by res0nat0r/nmap#1
Closed

ssh host-keys not shown correctly #2105

lmm-git opened this issue Aug 16, 2020 · 1 comment · Fixed by res0nat0r/nmap#1
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@lmm-git
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lmm-git commented Aug 16, 2020

Describe the bug
The NSE script ssh-hostkey seems to not produce any results on recent Debian based distributions (as scan target), although ssh-keyscan is producing correct results.

To Reproduce
nmap -p 22 -script ssh-hostkey vpn.iwt.rechenknecht.net is showing no results. Server is running unmodified versions of OpenSSH on Ubuntu 20.04.

nmap -p 22 -script ssh-hostkey jitsi.giz.berlin is producing correct results as expected. This server is running Ubuntu 18.04.

On both servers, ssh-keyscan is producing results as expected. Also both SSH-Servers are working as expected (login possible).

Expected behavior
For the first command I expect an output like this:

Starting Nmap 7.80 ( https://nmap.org ) at 2020-08-16 10:14 CEST
Nmap scan report for jitsi.giz.berlin (78.47.228.243)
Host is up (0.031s latency).
Other addresses for jitsi.giz.berlin (not scanned): 2a01:4f8:c0c:6a38::1

PORT   STATE SERVICE
22/tcp open  ssh
| ssh-hostkey: 
|   2048 98:a2:b2:a5:16:76:8f:e1:ee:a3:bc:1d:29:1e:f7:12 (RSA)
|   256 bd:b2:97:8a:a0:3d:36:3b:b9:0e:61:40:13:e6:26:30 (ECDSA)
|_  256 8d:ea:4c:41:6c:e7:20:bd:42:0b:a8:fc:c9:15:2a:1f (EdDSA)

Nmap done: 1 IP address (1 host up) scanned in 1.61 seconds

but am getting this:

Starting Nmap 7.80 ( https://nmap.org ) at 2020-08-16 10:14 CEST
Nmap scan report for vpn-01.cnr.marschke.me (168.119.53.147)
Host is up (0.032s latency).
Other addresses for vpn-01.cnr.marschke.me (not scanned): 2a01:4f8:c17:e31d::1
rDNS record for 168.119.53.147: static.147.53.119.168.clients.your-server.de

PORT   STATE SERVICE
22/tcp open  ssh

Nmap done: 1 IP address (1 host up) scanned in 1.46 seconds

Version info (please complete the following information):

  • OS: Ubuntu 20.04, Debian 10 (as scan target)
  • Scanning-OS: Kali Linux (latest updates installed as of 16th August

Additional context
Tested with nmap 7.60 as well.

@lmm-git lmm-git added the Nmap label Aug 16, 2020
@nnposter nnposter self-assigned this Aug 16, 2020
@nnposter nnposter added bug NSE and removed Nmap labels Aug 16, 2020
@nnposter
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Thank you for reporting the issue. There was a bug in library nselib/ssh2.lua that was causing the code to come to incorrect conclusion which key exchange algorithm should be used.

A fix has been committed as r37977. Please try again after refreshing this file from SVN or GitHub.

res0nat0r added a commit to res0nat0r/nmap that referenced this issue Oct 7, 2020
* Implement Ncat proxy creds via environment variable. Fixes nmap#2060, closes nmap#2073

* Fix --resume from IPv6 scans

* Use correct default buffer position. Closes nmap#2084

* Clarify upper boundary for variable-length numerical fields

* Make maximize_fdlimit return rlim_t on appropriate platforms. Closes nmap#2085. Fixes nmap#2079

* Credential object is creds.Account, not brute.Account. See nmap#2086

* Clarify location of the Error object

* Use correct default buffer position. Closes nmap#2086

* Minor optimization of url.parse_query()

* Output of matched fingerprints in http-default-accounts. Fixes nmap#2077

* Document that --open implies --defeat-rst-ratelimit since 7.40

* SNMP scripts are enabled on non-standard ports. See nmap#1473

* Increases SQL Server version resolution

* Eliminate reflection false positives in http-shellshock. Closes nmap#2089

* Unify AFP pathname serialization

* Correct AFP name extraction from responses. Closes nmap#2091
FPGetFileDirParms and FPEnumerateExt2 could crash due to unpacking from
out-of-bounds positions. This latent issue got exposed by converting from
bin.unpack to more stringent string.unpack

* Clarified parsing of the volume list in AFP FPGetSrvrParms

* Add cross references between the 2 whois scripts

* Streamline Boolean expressions

* Centralize AFP timestamp conversion to string

* Fix a word-wrapping issue

* Prevent SSH2 KEX confusion. Fixes nmap#2105

* Add ssh2.fetch_host_key() support for group 16

* Handle case of corrupted TCP options with length 0. Fixes nmap#2104

* Add iDRAC9 fingerprint to http-default-accounts. Closes nmap#2096

* fix license url: http -> https

* Implementation of TLS SNI override in Ncat
Closes nmap#2087, closes nmap#1928, fixes nmap#1927, fixes nmap#1974

* Fix off-by-one issue in last change. Fixes nmap#2107

* Be more strict with TCP options parsing, avoid reading off the end of TCP options. See nmap#2107

* Remove nmap-update

This feature was never publicly released, and has not been distributed
in our binary builds for a couple versions now. It needed to be removed
in order to reduce the number of places Nmap looks for data files. See nmap#2051

* If fetchfile didn't find the XSL, use a relative path on all platforms.

* Do not search NMAPDATADIR on Windows as it is not defined. See nmap#2051

* Remove an unused variable

* Require trailing '/' to match a directory name with --script. See nmap#2051

* Stop using Shellshock in header name. Fixes nmap#1983

* Fix line wrapping

* Speed improvement for script afp-ls. Closes nmap#2098

* New option --discovery-ignore-rst. Closes nmap#1616

* Nbase is needed for __attribute__ on Windows

* include string_pool in Windows build

* Use larger buffer size for socket errors (WSAETIMEDOUT was longer).

* Allow multiple UDP payloads per port. Closes nmap#1859 (payloads to be committed later)

* New UDP payloads. Closes nmap#1860

* Use ASCII chars for some payload data where it makes sense

* Pass error along instead of printing (link error)

* OpenSSL 1.1.X renamed libs: libeay32->libcrypto ssleay32->libssl

* More OpenSSL DLL name changes

* One last libeay32->libcrypto name change

* Fix loopback detection on Windows with new Npcap

* Add some popular favicon hashes

* Update nmap-mac-prefixes

* Update nmap-services from IANA

* Handle too-short response in s7-info. See nmap#2117

* Remove a todo item that is done (--resolve-all)

* Update dated 'class' network terms to CIDR. Closes nmap#2054

* Call superclass's init method from derived class

* Use signed value for tcp header offset and option lengths to detect underflow

* Correctly check for unsigned subtraction underflow.

* Add some missing changelog entries

* Tell LGTM to use the correct version of Python (2)

* Process new Linux and OpenBSD fingerprints

* Only get SSL options if we use them, currently for NO_SSLv2

* Process a few service fingerprint submissions

* Add a requested feature

* Try to make sure enough data is present before parsing. See nmap#2117

* Replace hyphens in the client SSH banner
Hyphen is not allowed in the software version string (RFC 4253, section 4.2)

* Update the SSH protocol flow. Closes nmap#1460
Allows the server to start the key exchange before the protocol version
exchange (banner exchange) is completed

* Silence static analysis warning

LGTM points out that since comparison with sizeof(buf) coerces n to
unsigned, all negative values become very large values, which are
necessarily larger than sizeof(buf), so the test is redundant. We still
want the test in our code to be explicit that we are checking for it, so
reordering the comparisons should silence the warning. A good optimizing
compiler should be able to combine the two conditions anyway.

See github/codeql#4249

* Be explicit about truncating division (timeout is in whole milliseconds)

* Improve docs on -Pn and host discovery

"Host discovery" is the preferred term over "ping scan" because of
confusion with ICMP Echo Request, a.k.a. "ping" as used by the "ping"
utility. Warn when users use -Pn because it has negative impact on scan
times since ultrascan timing parameters fall back to slow initial
defaults.

* Fix a config issue with LGTM (libverbs not linked in libpcap)

* Update IPv6 classifier based on new submissions through 2020-09-14

* Fix a meaningless error message when parsing IPv6 extension headers.

* Allow %F date format to mean YYYY-mm-dd like GNU date

* Remove duplicate test conditionals already tested in enclosing block

* Properly handle pcap reads in iocp engine. Fixes nmap#2126

Still has an odd code smell, but this fixes my test case with Nping.

* Add missing prototype

* Make IOCP the default Nsock engine on Windows. See nmap#2126

* Update macosx build to OpenSSL 1.1.1h, use jhbuild for all build steps

* Default rule base for script mysql-audit. See nmap#2125

* Avoid masked use of date before 1/1/1970 UTC. Fixes nmap#2136, closes nmap#2137

* Fix a CHANGELOG typo

* Reintegrate Nmap 7.90 release branch

* Bump version and regen docs for 7.90SVN post-release

* Only warn about protocol specs in port list with -p. Fixes nmap#2135

* Handle a weird IOCP error for UDP sockets. Fixes nmap#2140

Co-authored-by: nnposter <nnposter@e0a8ed71-7df4-0310-8962-fdc924857419>
Co-authored-by: dmiller <dmiller@e0a8ed71-7df4-0310-8962-fdc924857419>
@nmap nmap deleted a comment Apr 11, 2022
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