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Fix the address resolution for hostnames #84

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Merged
adfoster-r7 merged 2 commits into from
May 27, 2026
Merged

Fix the address resolution for hostnames #84

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3defcc3
Fix the address resolution for hostnames
zeroSteiner May 27, 2026
a2e1d9d
Fix the same issue but when binding
zeroSteiner May 27, 2026
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18 changes: 16 additions & 2 deletions lib/rex/socket/comm/local.rb
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Original file line number Diff line number Diff line change
Expand Up @@ -177,7 +177,15 @@ def self.create_by_type(param, type, proto = 0)
sock.setsockopt(::Socket::SOL_SOCKET, ::Socket::SO_REUSEADDR, true)
end

sock.bind(Rex::Socket.to_sockaddr(param.localhost, param.localport))
if Rex::Socket.is_ip_addr?(param.localhost)
ip = param.localhost
elsif param.v6
ip = Rex::Socket.getaddresses(param.localhost, true).select { |address| Rex::Socket.is_ipv6?(address) }.sample
else
ip = Rex::Socket.getaddresses(param.localhost, false).select { |address| Rex::Socket.is_ipv4?(address) }.sample
Comment on lines +183 to +185

@smcintyre-r7 smcintyre-r7 May 27, 2026

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Problem: choosing a resolved address via .sample makes socket binding/connecting non-deterministic and can cause intermittent failures when some returned addresses are unreachable/unusable.

This is by design and replicates real-world behavior. When there are multiple addresses, we should be choosing one at random.

end

@smcintyre-r7 smcintyre-r7 May 27, 2026

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.getaddresses will resolve the address which will raise Socket::ResolutionError when the name can't be resolved which seems like the correct behavior. ip will not be nil.

[3] pry(#<Msf::Modules::Auxiliary__Gather__Kerberoast::MetasploitModule>)> ::Addrinfo.getaddrinfo('doesnotexist.lan', 0, ::Socket::AF_UNSPEC, ::Socket::SOCK_STREAM)
Socket::ResolutionError: getaddrinfo: Name or service not known (Socket::ResolutionError)

sock.bind(Rex::Socket.to_sockaddr(ip, param.localport))

rescue ::Errno::EADDRNOTAVAIL,::Errno::EADDRINUSE
sock.close
Expand Down Expand Up @@ -256,7 +264,13 @@ def self.create_by_type(param, type, proto = 0)
ip = param.proxies.first.host
port = param.proxies.first.port
else
ip = Rex::Socket.getaddress(param.peerhost)
if Rex::Socket.is_ip_addr?(param.peerhost)
ip = param.peerhost
elsif param.v6
ip = Rex::Socket.getaddresses(param.peerhost, true).select { |address| Rex::Socket.is_ipv6?(address) }.sample
else
ip = Rex::Socket.getaddresses(param.peerhost, false).select { |address| Rex::Socket.is_ipv4?(address) }.sample
end
Comment on lines +267 to +273

@smcintyre-r7 smcintyre-r7 May 27, 2026

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This is incorrect, see #84 (comment)

port = param.peerport
end

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